Anna E Heino
email: anna.heino@thl.fi

Mika V J Gissler

Maili Malin

Heini Väisänen

Induced abortions by woman's country of origin in Finland 2001-2014

Keywords: induced abortion, migrant health, sexual and reproductive health

Aims

Understanding the differences in reproductive health behaviours between native and migrant populations helps provide good reproductive health services. We investigate the differences in induced abortion rates, pregnancy histories, and use of contraceptives between native and migrant populations in Finland.

Methods

The Finnish Register on Induced Abortions was linked with Population Register data from years 2001-2014 to identify first and second-generation immigrants. The data included 142,708 induced abortions.

Results

Abortion and contraceptive use varied between women of Finnish and foreign origins. Native women had a lower abortion rate than women born abroad. Women born in Somalia and India had the highest likelihood for having an abortion shortly after birth. The highest risk for having an abortion soon after previous induced abortion was among women born in Iran, Iraq, Somalia and former Yugoslavia. The risk for having more than two induced abortions was the highest for women born in Russia/the former Soviet Union and Estonia. Second-generation immigrants had a lower abortion rate than firstgeneration immigrants. Lack of contraceptive use prior to abortion was more common among women born abroad.

Conclusion

There were differences in pregnancy histories and in the use of reliable contraceptive methods before an induced abortion by country of birth. The higher likelihood for abortion after a recent birth among first-generation immigrants highlights the need for more targeted counselling immediately after childbirth. Although the abortion rate is lower among second-generation immigrants, the neglect of contraceptive use calls for additional education in sexual and reproductive health.

INTRODUCTION

Sexual and reproductive health is a key part of well-being. However, reproductive health is often overlooked in general discussion and in the health care system. In particular, vulnerable groups like migrants are easily marginalized as sexuality can be culturally a sensitive issue. There are signs that migrant women might have unmet contraceptive needs and migrant background may affect the way reproductive health and contraception is discussed by health care professionals with patients of migrant background. [START_REF] Raben | Inequity in contraceptive care between refugees and other migrant women? A retrospective study in Dutch general practice[END_REF][START_REF] Väisänen | Contraceptive use among migrant women with a history of induced abortion in Finland[END_REF] Migrants' countries of origin, reasons for immigration, time spent in the new country of residence and personal situations vary, and their health has no universal pattern. Some migrant groups have better health than natives and lower mortality [START_REF] Nielsen | Poorer self-perceived health among migrants and ethnic minorities versus the majority population in Europe: a systematic review[END_REF][START_REF] Salas-Wright | Immigrants and mental disorders in the United States: New evidence on the healthy migrant hypothesis[END_REF][START_REF] Fuller-Thomson | An investigation of the healthy migrant hypothesis: Pre-emigration characteristics of those in the British 1946 birth cohort study[END_REF][START_REF] Lehti | Mortality and causes of death among the migrant population of Finland in 2011-2013[END_REF] and they purchase less prescribed drugs [START_REF] Gimeno-Feliu | Patterns of pharmaceutical use for immigrants to Spain and Norway: a comparative study of prescription databases in two European countries[END_REF].

However, migrants' self-rated health seems to deteriorate over time spent in the host country which raises questions, how successful the social inclusion policies are and whether some migrants and their descendants are marginalized. "Healthy migrant effect" vanishes with second-generation migrantswomen in this group rate their health similarly as native women. [START_REF] Parra-Casado | Self-rated health and wellbeing among the workingage immigrant population in Western Europe: findings from the European social survey (2014) special module on the social determinants of health[END_REF][START_REF] Vandenheede | Mortality in adult immigrants in the 2000s in Belgium: a test of the 'healthy-migrant' and the 'migration-as-rapid-health-transition' hypotheses[END_REF] In terms of reproductive health, studies from the Nordic countries [START_REF] Helström | Abortion rate and contraceptive practices in immigrant and Swedish adolescents[END_REF][START_REF] Helström | Abortion rate and contraceptive practices in immigrant and native women in Sweden[END_REF][START_REF] Rasch | Induced abortion in Denmark: effect of socio-economic situation and country of birth[END_REF][START_REF] Eskild | Induced abortion among women with foreign cultural background in Oslo[END_REF] and Western Europe [START_REF] Rodriguez-Alvarez | Induced abortion in a Southern European region: examining inequalities between native and immigrant women[END_REF][START_REF] Picavet | Characteristics of women who have repeat abortions in the Netherlands[END_REF][START_REF] Zurriaga | Recourse to induced abortion in Spain: profiling of users and the influence of migrant populations[END_REF] show that migrant background and low socio-economic status are both risk factors for induced abortion. Migrant background seems also to be a risk for repeat abortions [START_REF] Picavet | Characteristics of women who have repeat abortions in the Netherlands[END_REF]. Abortion rate is one indicator for performance of sexual and reproductive health services. It reflects the quality of sexual health education, health care system's capacity to provide access to family planning services, and the availability and affordability of contraceptives. It also reflects sexual health practices in different cultures, and acceptability of contraceptive use. Low proportion of late abortions and planned use of contraceptives after abortion can be seen as indicators a well-functioning healthcare system and as a sign of good health literacy. A high prevalence of repeated abortions may indicate problems with contraceptive use or availability, access to health care or sexual education. [18] The migrant population in Finland is relatively small, but increased, from 0.8% in 1990 to 2.4 in 2001 to 5.9% in 2014. In 2014, 85% of the 322,700 persons of foreign origin were born outside of Finland (1 st generation immigrants). The largest immigrant populations are from former Soviet Union/Russia (20.7% of the total migrant population), Estonia (13.2%), Sweden (9.9%), Somalia (3.1%), and Iraq (3.1%).However, during the study period the proportion of migrant women from former Soviet Union/Russia and from Europe declined whereas the proportion of women from Asia (especially from China) and Africa increased. In 2014, 29.9% of the total migrant population were women of reproductive age. [18] In Finland, induced abortion has been legal since 1950, but an indication for abortion is required. The current legislation from 1970 is liberally interpreted, and 95% of abortions are performed on social grounds (including social circumstances, age of the woman [under 17 years or 40 years or more], or having four children or more). Other indications include fetal indication (4.2% of induced abortions in 2015), medical indication of the woman or father-to-be (0.7%), and ethical indication (less than 0.1%).

Termination of pregnancy is allowed until 20+0 gestational weeks by social, medical and ethical indications, or until 24+0 gestational weeks by fetal indication. On average, 10,000 induced abortions are performed annually in Finland. In 2015, the abortion rate was 8.2 per 1000 women aged 15-49 years which is the lowest of the Nordic countries. [START_REF]Laki raskauden keskeyttämisestä 239/1970[END_REF][START_REF]Induced abortions in the Nordic countries 2015[END_REF] According to a previous study on abortions among migrant women in Finland (1994)(1995)(1996)(1997)(1998)(1999)(2000)(2001)(2002), their abortion rate was lower than among native Finns. However, migrant women more often reported not using contraceptives prior to induced abortion or using a less effective method (condom). They had a higher mean number of previous pregnancies and their average age at the time of abortion was higher. [START_REF] Malin | Induced Abortions among Immigrant Women in Finland[END_REF] The aim of the current study is to investigate differences in the induced abortion rate, pregnancy histories, and use of contraceptives between the native and migrant populations.

METHODS

Finland is one of the few countries with a register on induced abortions [START_REF] Knudsen | Induced abortion among young women in the Nordic Countries[END_REF]. The validity of the Finnish Register on Induced Abortions is excellent (97% in 2011). [START_REF] Heino | How reliable are health registers? -The quality of the Finnish Register on Induced Abortions and Sterilisations[END_REF] The register contains information regarding all legally induced abortions in Finland. It includes patients' personal identity number (PIN), age, marital status, municipality, previous pregnancies before the induced abortion, contraception before and after the abortion, indication for the abortion, details of the procedure and length of gestation.

We linked the Finnish Register on Induced Abortions with the Population Register data on women's background characteristics from Statistics Finland. Information was linked using PIN. Immigrants and refugees are issued a PIN, if their residence permit is permanent or exceeds more than one year.

Asylum seekers who are applying for residence permit have no PINs and they T are excluded here. There were 148,114 induced abortions registered between 2001 and 2014. We excluded 1333 cases (0.9%), where PIN was either missing or incomplete. These include recent migrants, asylum seekers and non-resident women. The remaining data included 146,781 induced abortions among 115,047 women. These data were linked with the population data using the PIN and the year of the procedure.

In our final research data there were 146,062 induced abortions among 114,474 women. 719 cases (0.5%) were excluded because their PINs were not found in the Population Register. We had information about the age, pregnancy history and gestation length of these excluded cases but no information about their or their parents' birth country. These cases were compared to the final dataset and there were no differences in terms of available background characteristics. We further excluded 3354 women born abroad to Finnish parents from the data as this is a heterogeneous group that differs from women of Finnish origin born in Finland. The final research data covered 96.3% of all registered induced abortions.

We linked information on woman's and her parents' country of birth to identify migrant populations and were able to identify foreign-origin women born abroad (1 st generation migrants) and foreignorigin women born in Finland to parents of foreign background (2 nd generation migrants).

Women whose both parents or the only known parent were born abroad are considered to be of foreign origin. Women born abroad and whose parents' data were unknown are also classified as foreign origin. If at least one parent was born in Finland, a woman was categorized as being of Finnish origin.

A child adopted from abroad by parents born in Finland is defined as a person of Finnish origin. [18] The abortion rates were calculated by one thousand women years taking into account all women in reproductive age, from 15 to 49 years.

All analyses were conducted using the migrant generation (1 st or 2 nd generation) and the country of birth as the distinctive attributes. We used logistic regressions to adjust for background characteristics (age, cohabitation status, previous pregnancies when appropriate) between the different study groups using Finnish-origin women as the reference group. The associations are presented as odds ratios (ORs) with 95% confidence intervals (CIs). Analyses according to the country of birth were only conducted if the data contained at least 200 women born in the country in order to minimise the effect of random variation and to follow the data protection practices.

Studies based on register data only do not need an ethical review board clearance in Finland.

RESULTS

Of the 142,708 induced abortions 90.9% were performed to Finnish-born women of Finnish origin (Table 1). However, the proportion of induced abortions performed to women of foreign origin increased from 6.4% in 2001 to 11.7% in 2014. In total, 98.2% of foreign-origin women who had an induced abortion were first-generation immigrants.

The mean age of women of Finnish origin undergoing induced abortion was 26.3 years and 28.6 years among women of foreign origin born abroad. The mean age of 21.4 for second-generation immigrants reflected the younger age structure of this population (Tables 1 and2). The younger mean age could also be seen in their reproductive history with fewer previous pregnancies, induced abortions and births.

The proportion of teenagers (under 20 years) who had an induced abortion was clearly higher among women of Finnish origin (21.2 %) than among women of foreign origin (9.9%), as was the proportion of minors (9.6% vs 4.1%, respectively). Of first generation migrants, only women born in Somalia had a higher proportion of teenagers (22.0%) having abortions than women of Finnish origin born in Finland. Among women born in China or India the proportion was substantially lower (1.8% and 3.0%). Of second-generation migrants having an induced abortion 57.4% were teenagers.

Abortion rates

The abortion rate was higher (15.0/1000 person years) among women of foreign origin than among those of Finnish origin (8.5/1000). There was a significant difference between women of foreign origin born in Finland (2 nd generation) or abroad (1 st generation). Women born in Finland regardless of their origin had significantly lower abortion rate than women born abroad. (Table 2.) Of first generation migrants, the highest abortion rates were among women born in Iran (26.3/1000), Vietnam (20.8/1000) and Estonia (19.0/1000).

For teenagers, the abortion rate was markedly different between first generation migrants (19.5/1000), second generation migrants (9.5/1000) and women of Finnish origin (13.0/1000). Of teenaged first generation migrants, the highest abortion rates were among women born in Sweden (38.6/1000) and Vietnam (30.8/1000).

Pregnancy history

Among women obtaining an induced abortion in 2001-2014, 20.0% had given birth or had an earlier induced abortion during the same or previous year.

Adjusted for woman's age and cohabitation, all women of foreign origin (1 st and 2 nd generation) had a higher likelihood (OR 1.18, CI 1.11-1.24) for having recently given birth before the induced abortion compared to women of Finnish origin. Of first generation migrants, women born in Somalia (OR 2.10, CI 1.63-2.69) and India (OR 1.90, CI 1.41-2.55) were the most likely to have recently given birth.

Compared to second generation, first-generation immigrants had an over three-fold risk (OR 3.31, CI 1.68-6.53) for having recently given birth.

The likelihood for having had at least two previous births before the induced abortion was higher among women of foreign origin than for women of Finnish origin (OR 1.11, CI 1.06-1.17). Of first generation migrants, this likelihood was the highest for women born in the former Yugoslavia (OR 3.18, CI 2.50-4.04), Somalia (OR 2.85, CI 2.27-3.56), Vietnam (1.95, CI 1.56-2.43) and Iraq (OR 1.71, CI 1.37-2.14). (Table 3.) First-generation migrants had a 3.5-fold (OR 3.55, CI 1.97-6.39) likelihood for at least two previous births at the time of induced abortion compared to second generation migrants.

The risk for a recent induced abortion was over 1.5-fold for women of foreign origin (OR 1.60, CI 1.51-1.70) than for women of Finnish origin. The highest risk for a previous induced abortion the same year or the year before was among women born in Iran (OR 2.41, CI 1.85-3.13), Iraq (OR 2.24, CI 1.72-2.92), Somalia (OR 2.11, CI 1.63-2.73) and the former Yugoslavia (OR 1.83, CI 1.35-2.47).

Compared to second generation, the risk for a recent abortion was higher for first generation migrants (OR 1.57, CI 1.00-2.45).

Compared to women of Finnish origin, the risk for having at least two previous induced abortions at the time of the most recent abortion was almost two-fold (OR 1.85, CI 1.77-1.94) for women of foreign origin. The risk for having at least two previous induced abortions was the highest for women born in former Soviet Union /Russia (OR 3.00, CI 2.79-3.23) and Estonia (OR 2.17, CI 1.95-2.42).

(Table 3.) The risk for having five or more previous induced abortions was 2.8-fold for women of foreign origin (OR 2.77, CI 2.38-3.22). Compared to second generation, first-generation immigrants had a two-fold risk (OR 2.19, CI 1.31-3.67) for at least two previous induced abortions) at the time of induced abortion.

Second-generation immigrants had a substantially decreased likelihood for at least two previous births (OR 0.33, CI 0.18-0.60) and a recent childbirth (OR 0.41, CI 0.21-0.80) than women of Finnish origin born in Finland also when standardized by the age of the woman.

Gestational age and indication for induced abortion

Adjusted for woman's age, cohabitation and the number of previous pregnancies, women of Finnish origin had a higher risk (OR 1.39, CI 1.30-1.49) of obtaining an abortion at or after 12 gestational weeks than women of foreign origin. However, first generation migrant-women born in Somalia (OR 1.52, CI 1.15-2.00) or Thailand (OR 1.38, CI 1.05-1.81) had a higher risk for a second trimester abortion than women of Finnish origin. (Table 4.) Many of these abortions were due to fetal indication, the probability of which increases by age. However, the risk for termination on fetal indication was higher (OR 1.40, CI 1.16-1.69) among women of Finnish origin also when standardized by gestational age.

Contraceptive use

In total, 41.2% of women did not report any use of contraceptives when they came pregnant. Women of foreign origin had twice (OR 1.96, CI 1.92-2.05) the risk for not using contraceptives before the induced abortion than women of Finnish origin when adjusted for woman's age, cohabitation, and the number of previous pregnancies. This risk was higher for women born in Somalia (OR 3.16, CI 2.61-3.84), Vietnam (OR 2.85, CI 2.34-3.46), the former Yugoslavia (OR 2.85, CI 2.33-3.48), Iran (OR 2.78, CI 2.29-3.37) and Iraq (OR 2.70, CI 2.23-3.27) than among women of Finnish-origin. The risk for not using contraceptives was higher for first-generation than second-generation immigrants (OR 1.52, CI 1.17-1.99). Second-generation immigrants had a higher risk for lack of contraceptive use (OR 1.37, CI 1.06-1.78) than women of Finnish origin.

Women of Finnish origin more commonly reported oral contraceptives as their planned contraceptive method (53.7%) than women of foreign origin (48.5%). On the other hand, an IUD was more commonly planned for women of foreign origin (32.8% vs 24.0%) as were other long acting reversible contraceptive (LARC) methods, implant and injection (3.7% vs 2.6%). Still, the odds for either IUD or other LARC method being the planned contraceptive were slightly elevated for women of Finnish origin (OR 1.18, CI 1.13-1.23).

DISCUSSION

We used Finnish register data on induced abortions to widen our knowledge on reproductive health among migrants in Finland. In this study, we concentrated on issues that can be targeted with culturally sensitive sexual education and actions of the health care system. There were significant differences in induced abortion and contraceptive use between women of Finnish and foreign origin, and between first and second-generation immigrants. The abortion rate was markedly higher among first and second-generation immigrants than among women of Finnish origin born in Finland. This contradicts an earlier study that showed lower abortion rates among migrant women than among women of Finnish origin [START_REF] Malin | Induced Abortions among Immigrant Women in Finland[END_REF].

Women born in Finland regardless of their origin have significantly lower abortion rates than women born abroad. This seems to confirm the hypothesis that second-generation women adopt to the culture of the host country relatively quickly [START_REF] Loeber | Sexual and reproductive health issues of Turkish immigrants in the Netherlands[END_REF] and their health behaviour is often closer to the original population than to that of their parents.

Though the number of abortions was relatively low among second-generation immigrants, our study shows the lack of contraceptive use in this group. Although infrequent substance use, dating and intercourse seems to protect the migrant youth from unwanted pregnancies [START_REF]Indicator Justifiable: abortion[END_REF], their neglect of contraceptive use seems to point to a further need of culturally sensitive sexual education. Youth from migrant families have been found to generally have a lower sexual and reproductive awareness than native youth [26]. Possible generational cultural tensions and silence about sexuality might lead to risk behaviour among some migrant youth as moral and religious views may impact contraceptive use [27].

Strengths and limitations

The main strength of this study is the use of population based register data, good quality of the data [START_REF] Heino | How reliable are health registers? -The quality of the Finnish Register on Induced Abortions and Sterilisations[END_REF][START_REF] Gissler | Declining Induced Abortion Rate in Finland: Data Quality of the Finnish Abortion Register[END_REF] and the ability to separate first and second generation migrants. Most previous studies are based on surveys, which suffer from underreporting of abortions [START_REF] Jones | Underreporting of induced and spontaneous abortion in the United States: an analysis of the 2002 National Survey of Family Growth[END_REF][START_REF] Jokela | Births and induced abortions among women of Russian, Somali and Kurdish origin, and the general population in Finland -comparison of self-reported and register data[END_REF] and may struggle to include enough immigrant women. Surveys aimed at migrant populations coverage issues might arise due to language and cultural barriers, particularly with themes considered sensitive like induced abortion.

Our data, however, did not include induced abortions conducted in other countries. This may underestimate the number of cases from neighbouring countries, especially nearby countries Estonia and Russian Federation. Some women, e.g. recent migrants may opt to have the procedure in their previous country of residence.

Information about pregnancy history in the register is based on women's self-report, but this information is double-checked in the register, i.e. if a woman reports no previous abortions, but abortion(s) can be found in the register, the self-reported information is corrected. Earlier study has shown that survey-based and register-based information on pregnancy history differ somewhat. Undercoverage of births in the register was observed whereas information on previous induced abortions was more accurate in the register. [START_REF] Jokela | Births and induced abortions among women of Russian, Somali and Kurdish origin, and the general population in Finland -comparison of self-reported and register data[END_REF] While a major benefit of our study is the possibility to separate first and second-generation immigrants, we were not able to study the length of stay in Finland or the effects of socio-economic factors. Neither did we have information on the reason for migrating to Finland. These factors are known to affect the health of migrants as the healthy migrant effect seems to diminish with the time lived in the host country [START_REF] Parra-Casado | Self-rated health and wellbeing among the workingage immigrant population in Western Europe: findings from the European social survey (2014) special module on the social determinants of health[END_REF][START_REF] Vandenheede | Mortality in adult immigrants in the 2000s in Belgium: a test of the 'healthy-migrant' and the 'migration-as-rapid-health-transition' hypotheses[END_REF] and socio-economic status in known to correlate with health [START_REF] Nielsen | Poorer self-perceived health among migrants and ethnic minorities versus the majority population in Europe: a systematic review[END_REF][START_REF] Helström | Abortion rate and contraceptive practices in immigrant and native women in Sweden[END_REF].

Conclusions

In Finland, where contraceptives are easily available, abortion is legal and there is a universal right for health care services, ethnic differences in abortion rates can be seen as a sign of differences in health literacy, acceptability of contraceptive use and attitudes towards induced abortion as a family planning method. Our results show that there are ethnic differences in pregnancy histories and in the use of reliable contraceptive methods, and these differ by generation.

Our data showed that the proportion of migrant women not using any contraceptives prior to abortion was (50% of those seeking abortion) and has stayed relatively stable [START_REF] Malin | Induced Abortions among Immigrant Women in Finland[END_REF] during last decades implying a further need to address this issue.

An earlier study also found that there are differences between women of migrant origin and women of Finnish origin in adopting an effective contraceptive method after an induced abortion. [START_REF] Väisänen | Contraceptive use among migrant women with a history of induced abortion in Finland[END_REF] As effective contraceptive use reduces unintended pregnancies and subsequently abortion rates, the use of one is essential and should be encouraged, especially after an induced abortion or a birth, and the differences in planned contraceptive method should be addressed in the health care system.

The higher likelihood for a recent birth among first-generation immigrants at the time of abortion highlights the need for more targeted counselling immediately after giving birth. According to a Finnish survey, the infrequent use of contraceptives among married women of Somali descent seems to be connected with religious beliefs and issues involving marital relations [START_REF] Degni | Attitudes towards and perceptions about contraceptive use among married refugee women of Somali descent living in Finland[END_REF]. Our study suggests that among first-generation immigrants, induced abortion is more common than in other groups. Thus, cultural, religious and social issues involved in the use of family planning should not be underestimated. In cultures where attitudes towards contraception might be negative, an induced abortion might be a discreet way of preventing having more children.

Our study does not support the earlier findings that immigrant women have a higher probability of having an induced abortion after the first trimester [START_REF] Loeber | Factors influencing the percentage of second trimester abortions in the Netherlands[END_REF]. Among women of Finnish origin, the higher risk for induced abortion due to fetal indication might be explained by better understanding of the fetal screening system and options available. On the other hand, other reasons, for example religious and cultural beliefs, might explain the lower risk among migrant origin women. However, our results also suggest the importance to ensure that health care services are provided and given equally for women of all origins.

Our study underlines the differences between first and second-generation migrants. It is essential to ensure adequate contraceptive advice right after childbirth and induced abortion especially for firstgeneration migrant women. For second-generation immigrants, adequate reproductive knowledge, access to care and sexual and reproductive health services should be ensured. All omnibus chi square tests were significant (<.0001) Notes: Adjusted for the age of the woman, cohabitation and the number of previous births and induced abortions. Finland (ref.

) includes women of Finnish origin born in Finland.

Table 1 .

 1 Background characteristics of women having an induced abortion in Finland 2001-2014

		Of foreign origin, born	Of foreign origin,
	Of Finnish origin, born	abroad	born in Finland
	in Finland	(1st generation	(2nd generation
		migrant)	migrant)

Table 3 .

 3 Odds ratios (OR) for previous pregnancies by the country of birth of first generation migrants.Previous pregnancy ended either in an induced abortion (IA) or a birth

At the time of the IA, two or more previous pregnancies that During the same or previous year as the IA, had a pregnancy that

  Notes: Adjusted for the age of the woman and cohabitation. Finland (ref.) includes women of Finnish origin born in Finland.

	Country of birth	ended in IA	ended in birth	ended IA	ended in birth
	Finland (ref.)	1.00	1.00	1.00	1.00
	Former Soviet Union/Russia	3.00 (2.79-3.23)	0.90 (0.83-0.97)	1.50 (1.34-1.67)	1.00 (0.91-1.11)
	Sweden	1.08 (0.70-1.66)	1.64 (1.12-2.30)	1.32 (0.80-2.17)	1.43 (0.97-2.12)
	Estonia	2.17 (1.95-2.42)	1.47 (1.32-1.64)	1.61 (1.39-1.86)	1.09 (0.96-1.25)
	Somalia	1.50 (1.14-1.94)	2.84 (2.27-3.56)	2.11 (1.63-2.73)	2.10 (1.63-2.69)
	Iran	1.76 (1.39-2.22)	1.12 (0.89-1.41)	2.41 (1.85-3.13)	0.70 (0.51-0.96)
	Iraq	1.17 (0.89-1.54)	1.71 (1.37-2.14)	2.24 (1.72-2.92)	1.31 (1.03-1.68)
	Thailand	0.79 (0.58-1.07)	1.10 (0.88-1.39)	1.45 (1.04-2.01)	0.81 (0.60-1.10)
	Vietnam	1.42 (1.11-1.84)	1.95 (1.56-2.43)	1.64 (1.21-2.21)	1.44 (1.12-1.86)
	China	1.26 (0.98-1.64)	0.26 (0.20-0.33)	1.21 (0.85-1.73)	1.00 (0.76-1.31)
	Former Yugoslavia	1.80 (1.41-2.30)	3.18 (2.50-4.04)	1.83 (1.35-2.47)	1.43 (1.11-1.83)
	India	0.62 (0.38-1.01)	0.68 (0.50-0.91)	0.91 (0.52-1.59)	1.90 (1.41-2.55)
	Other countries	1.18 (1.07-1.31)	1.05 (0.96-1.14)	1.60 (1.43-1.79)	1.28 (1.17-1.40)
	Born abroad, total	1.85 (1.77-1.94)	1.11 (1.06-1.17)	1.60 (1.51-1.70)	1.16 (1.10-1.23)

Table 4 .

 4 Odd ratios (OR) and proportions of abortions by gestational age by the country of birth of first generation migrants

						Total n of
						induced
						abortions 2001-
	Country of birth	12+ OR	12+ %	20+ OR	20+ %	2014
	Finland (ref.)	1.00	10.0	1.00	1.1	129,978
	Former Soviet Union/Russia	0.54 (0.47-0.62)	5.8	0.61 (0.42-0.90)	0.7	3882
	Sweden	0.81 (0.49-1.36)	8.4	0.88 (0.22-3.57)	1.1	190
	Estonia	0.67 (0.56-0.80)	7.1	0.45 (0.23-0.86)	0.5	2015
	Somalia	1.52 (1.15-2.01)	12.6	1.55 (0.58-4.18)	0.9	468
	Iran	0.65 (0.45-0.93)	6.9	0.51 (0.16-1.59)	0.7	449
	Iraq	0.93 (0.68-1.28)	9.5	0.98 (0.40-2.37)	1.1	453
	Thailand	1.38 (1.05-1.81)	14.3	1.26 (0.62-2.55)	1.9	421
	Vietnam	1.04 (0.77-1.41)	10.9	0.61 (0.20-1.92)	1.1	448
	China	0.45 (0.29-0.67)	5.8	0.24 (0.06-0.96)	0.5	432
	Former Yugoslavia	0.83 (0.58-1.17)	8.6	1.09 (0.45-2.65)	1.2	417
	India	0.35 (0.18-0.65)	4.5	0.45 (0.11-1.81)	0.9	222
	Other countries	0.76 (0.67-0.87)		0.85 (0.61-1.18)
	Born abroad, total	0.72 (0.67-0.77)	7.7	0.69 (0.57-0.85)	0.9	12,966

ACKNOWLEDGEMENTS

The results were orally presented at the International Congress of World Federation of Public Health Associations 2017, Melbourne, Australia, 3.-7.4.2017.

CONFLICTS OF INTEREST

None of the authors have conflicts of interest regarding this article. The author(s) received no financial support for the research, authorship, and/or publication of this article. 1 Includes all induced abortions performed to under 20 years.

2 Includes all induced abortions performed to women over 49 years.


Heini Väisänen
email: h.e.vaisanen@soton.ac.uk

Päivikki Koponen

Mika Gissler

Osmo Kontula

Contraceptive use among migrant

Keywords: Family planning, Finland, induced abortion, migrant health, sexual and reproductive health

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Introduction

Contraceptive non-use or failure may lead to unintended pregnancy. Around half of such pregnancies are terminated [START_REF] Sedgh | Intended and unintended pregnancies worldwide in 2012 and recent trends[END_REF]. Women's contraceptive choices may change after an induced abortion, for instance due to post-abortion contraceptive counselling [START_REF] Schunmann | Specialist contraceptive counselling and provision after termination of pregnancy improves uptake of long-acting methods but does not prevent repeat abortion: a randomized trial[END_REF] or because the experience prompted a behavioural change [START_REF] Moreau | Patterns of contraceptive use before and after an abortion: results from a nationally representative survey of women undergoing an abortion in France[END_REF]. For example, in Helsinki 75% of women adopt a reliable contraceptive method after an abortion [START_REF] Heikinheimo | Can the outcome of the next pregnancy be predicted at the time of induced abortion?[END_REF] and in many European countries those with a history of abortion are more likely to use contraceptives than those without [START_REF] Moreau | Patterns of contraceptive use before and after an abortion: results from a nationally representative survey of women undergoing an abortion in France[END_REF][START_REF] Spinelli | Patterns of contraceptive use in 5 European countries. European Study Group on Infertility and Subfecundity[END_REF], or to change methods after an abortion [START_REF] Bianchi-Demicheli | Contraceptive practice before and after termination of pregnancy: a prospective study[END_REF].

The effect of abortion on contraceptive use may vary depending on the woman's sociocultural background, which is important as it influences sexual and reproductive behaviours including abortion and contraceptive use [START_REF] Moreau | Patterns of contraceptive use before and after an abortion: results from a nationally representative survey of women undergoing an abortion in France[END_REF][START_REF] Jones | Contraceptive use among U.S. women having abortions in 2000-2001[END_REF]. Many religions control sexuality and restrict family planning use. For example, depending on the denomination of Christianity, contraceptive use might either be fully prohibited or left to the discretion of the couple [START_REF] Srikanthan | Religious and cultural influences on contraception[END_REF]. Similarly, depending on the interpretation of Islam, contraception might be restricted to a small selection of traditional methods, or all reversible methods might be allowed [START_REF] Srikanthan | Religious and cultural influences on contraception[END_REF]. Both religions tend to prohibit abortion in most situations [START_REF] Srikanthan | Religious and cultural influences on contraception[END_REF].

Sociocultural background may affect abortion behaviour and contraceptive use via the cultural values and practices of the country of origin. Abortions were common in Russia and in the former Soviet Union due to the lack of reliable contraceptive methods and the belief that contraceptive use was dangerous [START_REF] Haavio-Mannila | Sexual trends in the Baltic Sea area[END_REF][START_REF] Ihamäki | Russian roulette -the barriers and needs of family planning among adolescents in St Petersburg and Riga[END_REF][START_REF] Regushevskaya | Contraceptive use and abortion among women of reproductive age in St. Petersburg, Russia[END_REF][START_REF] Remennick | Family planning practices and attitudes among former Soviet new immigrant women in Israel[END_REF]. In Estonia, differences in sociocultural backgrounds might have influenced post-abortion contraceptive use in Russian-and Estonian-speaking women: while previous abortion was associated with an increased risk of not using a method among Russian-speaking women, the opposite was true for Estonian-speaking women [START_REF] Laanpere | Ethnic differences in factors associated with the use of contraception among 20-to 44-year-old women in Estonia and St. Petersburg, Russia[END_REF]. In Finland, migrants of Russian origin have a higher age-specific abortion rate compared with the general population [START_REF] Malin | Induced abortions among immigrant women in Finland[END_REF].

Their post-abortion contraceptive use has, however, not been previously studied.

Many Kurdish migrants in Finland come from Iran or Iraq. In Iran, abortion is morally condemned by the religious authorities and is legal only on very restricted grounds [START_REF] Hosseini-Chavoshi | Social and psychological consequences of abortion in Iran[END_REF]. Nevertheless, in 2013, 31% of Iranian women reported an unwanted pregnancy [START_REF] Motlaq | Contraceptive use and unmet need for family planning in Iran[END_REF], and 17% reported having had an abortion [START_REF] Ranji | Induced abortion in Iran: prevalence, reasons, and consequences[END_REF]. Abortion rates in Iraq are not known, but abortion legislation is very strict [START_REF]The world's abortion laws[END_REF].

Abortion statistics for Somalia are not available, but abortion is only allowed to preserve a woman's health, resulting in illegal, unsafe abortions that are a substantial cause of maternal mortality [START_REF] Gure | Emergency contraception in post-conflict Somalia: an assessment of awareness and perceptions of need[END_REF][START_REF] Sorbye | A situation analysis of reproductive health in Somalia[END_REF]. A qualitative study in the USA suggested that young, sexually active immigrant Somali women may have abortions due to lack of contraceptive knowledge, as contraception is a taboo subject in many families [START_REF] Pavlish | Somali immigrant women and the American health care system: discordant beliefs, divergent expectations, and silent worries[END_REF].

Somali women in Finland may be more aware of contraception than their counterparts in the USA, but still need to negotiate its use with their partner and religious beliefs [START_REF] Degni | Attitudes towards and perceptions about contraceptive use among married refugee women of Somali descent living in Finland[END_REF]. Sociocultural background is not the only factor associated with abortion and contraceptive use. Migrant women may be less likely to use contraceptives compared with native women, for example due to literacy or language issues, and/or lower socioeconomic position causing difficulties within the health care system [START_REF] Derose | Immigrants and health care: sources of vulnerability[END_REF]. Women from disadvantaged backgrounds [START_REF] Martinez | Teenagers in the United States: sexual activity, contraceptive use, and childbearing, 2006-2010 national survey of family growth[END_REF], with low education or no partner [START_REF] Spinelli | Patterns of contraceptive use in 5 European countries. European Study Group on Infertility and Subfecundity[END_REF][START_REF] Frost | Factors associated with contraceptive use and nonuse, United States, 2004[END_REF], report low contraceptive use and have a higher likelihood of experiencing an abortion [START_REF] Väisänen | The association between education and induced abortion for three cohorts of adults in Finland[END_REF].

Finnish context

Migration to Finland has increased rapidly since the 1990s. In 2012, 5.3% of the population was foreign-born [START_REF]Population structure 2012[END_REF]. The largest migrant groups are those born in Russia or the former Soviet Union, Sweden, Estonia, Somalia, Iraq, China and Thailand [START_REF]Population structure 2012[END_REF].

Many Somali and Kurdish migrants are refugees [START_REF] Castaneda | Migrant health and wellbeing -study of the Russian, Somali and Kurdish populations in Finland[END_REF].

In Finland, there are no substantial limitations in obtaining abortions within the first trimester [START_REF] Knudsen | Induced abortion in the Nordic countries: special emphasis on young women[END_REF]. Abortion rates in Finland are lower than in many other Western countries [START_REF] Denisov | Divergent trends in abortion and birth control practices in Belarus, Russia and Ukraine[END_REF] and are the lowest in the Nordic countries [START_REF] Gissler | Induced abortions in the Nordic countries[END_REF]. In 2011, the abortion rate was 9/1000 women of reproductive age [START_REF] Heino | Induced abortions 2011[END_REF]. Family planning services are offered in all municipalities and the first 3 months of oral contraceptives or the first intrauterine device (IUD) are often free of charge [START_REF] Hemminki | Quality of contraceptive services in Finland[END_REF][START_REF] Sannisto | Provision of contraception: a survey among primary care physicians in Finland[END_REF].

Aim of the study

The aim of the study was to compare the association between having had at least one abortion and current contraceptive use among Kurdish, Somali and Russian originmigrants and the general population in Finland. We examined whether women's sociocultural background interacted with the likelihood of adopting a modern contraceptive method after an abortion. Our study was designed to examine the importance of sociocultural background: we included women from different backgrounds who lived in the same context at the time of experiencing an abortion. Thus, factors other than sociocultural factors affecting contraceptive uptake after abortion, such as availability of contraceptives and post-abortion counselling, were standardised. Although we know that in Finland not using contraceptives prior to abortion was more common among migrant women from Iran, Iraq or Afghanistan (54%) and among women from the former Soviet Union and Russia (55%) than among Finnish women (35%) seeking abortion [START_REF] Malin | Induced abortions among immigrant women in Finland[END_REF], there is a lack of research examining contraceptive use after an abortion.

Methods

Data collection and participants

We used data from three sources: two health surveys (the Migrant Health and Wellbeing study and the Health 2011 study) combined with the Finnish register of induced abortions.

The Migrant Health and Wellbeing study 2010-2012 (Maamu) surveyed migrants of Somali, Russian and Kurdish origin who had resided in Finland for at least 1 year.

Participants were recruited from six municipalities with a high number of migrants: Helsinki, Espoo and Vantaa from the capital metropolitan area, and Turku, Tampere and Vaasa from southern and western Finland. At that time, 93% of Somali, 67% of Kurdish and 47% of Russian origin migrants lived in these municipalities. Selection criteria for the Russian group was Russia or the former Soviet Union as the country of birth and Russian or Finnish as the native language; the Somali group included those born in Somalia; the Kurdish group included those born in Iraq or Iran with the native language of Kurdish. Participants aged 18-64 (n=1000) were sampled from each of the migrant groups, using stratified random sampling by municipality and group. In this sample, 622 in the Russian, 531 in the Somali and 426 in the Kurdish group were women. Overall, 70% of the Russian, 51% of the Somali and 63% of the Kurdish population participated in the survey [START_REF] Castaneda | Migrant health and wellbeing -study of the Russian, Somali and Kurdish populations in Finland[END_REF][START_REF]Background of the Maamu study[END_REF]. A comparison group of the general Finnish population was selected from the national sample of the Health 2011 study [START_REF] Lundqvist | Health 2011 survey -methods[END_REF] including all sampled individuals of the same age in the six municipalities (n=2276).

Both surveys were linked to the Finnish register of induced abortions. All physicians performing abortions in Finland are required by law to register the event [START_REF]Register of induced abortions[END_REF].

According to a recent evaluation, the register captures 97% of abortions [START_REF] Heino | How reliable are health registers? Registration of induced abortions and sterilizations in Finland[END_REF]. The register provides reliable information about abortions, which are usually severely underreported in surveys [START_REF] Jones | Underreporting of induced and spontaneous abortion in the United States: an analysis of the 2002 National Survey of Family Growth[END_REF]. All non-pregnant women aged 18-44 of Somali (n=124), Russian (n=183) and Kurdish (n=164) origin and of the general female population (n=187) were included in our study.

The National Institute for Health and Welfare obtained ethical approval for the study, including approval to link register and survey data, from the Coordinating Ethical Committee of the Helsinki and Uusimaa Hospital Region. The register linkage was described in the participants' written informed consent. Ethical approval to analyse the data for this study was also obtained from the University of Southampton Ethics Board.

Measures

Our outcome variable was current contraceptive use. Those using any of the following methods were counted as a contraceptive user: oral contraceptive, ring, patch, IUD, sterilisation or condom.

The main explanatory variable was history of induced abortion in Finland. We put women into 'never abortion' and 'ever abortion' groups based on data from the abortion register. Although women were also asked to report their abortion experiences in the two surveys, we did not include this information. First, abortions are usually underreported [START_REF] Jones | Underreporting of induced and spontaneous abortion in the United States: an analysis of the 2002 National Survey of Family Growth[END_REF]. Thus, we would have had complete information regarding abortions obtained in Finland (from the register), but incomplete information regarding abortions obtained elsewhere (self-reported). Second, since women were not asked to self-report the timing of their abortion, we would not have been able to control for time since abortion for the self-reported variable. Third, an abortion obtained in Finland or elsewhere may have a different effect on contraceptive behaviour, particularly if the abortion was illegal or unsafe. In these contexts, women do not receive post-abortion contraceptive counselling [START_REF] Rogers | Access to contraception and sexual and reproductive health information post-abortion: a systematic review of literature from low-and middle-income countries[END_REF] and many suffer from adverse health consequences [START_REF] Shrivastava | Unsafe abortion: a cruel way of birth control[END_REF].

Other explanatory variables from the surveys were education (less than upper secondary vs at least upper secondary), age, parity (number of live births) and relationship status (single, married, cohabiting or separated/divorced/widowed). For those who had ever had an abortion, we also included years since the most recent abortion took place, and whether the women used modern contraceptives before their most recent abortion (the latter based on self-reporting before the procedure) from the abortion register. Previous contraceptive use was not recorded for those who had never had an abortion. For immigrant women we included an indicator of whether they migrated to Finland before age [START_REF] Motlaq | Contraceptive use and unmet need for family planning in Iran[END_REF], to indicate their exposure to the Finnish education system (it is compulsory to go to school until age 16). This is important because sexuality education is delivered in all schools, and because schools are important places for socialisation. We also controlled for self-reported religion (Muslim vs other) among migrants. Information about religion was not collected for the general population, but around 78% of the Finnish population in 2011 were Lutheran or Greek Orthodox [START_REF]Population structure. Appendix table 2: religious affiliation of the population, share of population, % 1950-2013[END_REF].

The outcome variable and most explanatory variables were extracted from the two surveys. The exceptions are the history of induced abortion, time since last abortion and contraceptive use before abortion variables, which we obtained from the register of induced abortions.

Analysis

Our aim was to estimate whether having an abortion was associated with current contraceptive use, while controlling for a range of adjustment variables.

Results from a standard logistic regression regarding the effect of abortion may be biased if some characteristics are associated with both the likelihood of experiencing an abortion and using contraception (i.e. a selection effect). Therefore, we analysed these data using propensity score weighted logistic regression [START_REF] Dugoff | Generalizing observational study results: applying propensity score methods to complex surveys[END_REF][START_REF] Morgan | A diagnostic routine for the detection of consequential heterogeneity of causal effects[END_REF][START_REF] Austin | An introduction to propensity score methods for reducing the effects of confounding in observational studies[END_REF].

Propensity score is the probability of having an abortion given a set of observed baseline characteristics. The score can be used to weight our observational study so that it to an extent mimics a randomised controlled trial: it balances the sample so that those who had an abortion, and those who did not, have a similar distribution of baseline characteristics [START_REF] Austin | An introduction to propensity score methods for reducing the effects of confounding in observational studies[END_REF]. The propensity score is a predicted probability from a logistic regression model, where the baseline characteristics predict the likelihood of having an abortion.

We calculated average treatment effect on the treated (ATT) weights [START_REF] Morgan | A diagnostic routine for the detection of consequential heterogeneity of causal effects[END_REF], which leave the group that experienced an abortion unaltered. Those who had never had an abortion were weighted with propensity scores to cancel the selection effect by making the baseline characteristics of this group similar to those of the abortion group. ATT weights estimate the average effect of having an abortion on current contraceptive use among those who have a high propensity for abortion. In other words, if a woman who had had an abortion had not conceived at that time (and hence avoided the abortion), would her current contraceptive use have been any different [START_REF] Su | Better for baby? The retreat from mid-pregnancy marriage and implications for parenting and child well-being[END_REF]. The appendix provides a technical explanation of the methods used.

Inverse sampling probability weights were applied and finite populations were accounted for in all analyses to correct for non-response and different sampling probabilities. The propensity score weights were multiplied by the sampling weights.

We first calculated the propensity score, which is the probability of having an abortion using birth cohort, immigrant background, religion, age moved to Finland and education as baseline variables (Appendix Table 1). We used these propensities as weights among the 'never abortion' group. We confirmed that the baseline characteristics were balanced with respect to history of induced abortion, i.e. the means of the baseline characteristics were similar in both groups (ever abortion vs never abortion) (Appendix Table 2). These weights were used in a logistic regression model estimating the likelihood of being a current contraceptive user. In this model we included the baseline characteristics, current partnership status, years since last abortion, number of live births and interaction between abortion and immigrant background. We conducted two sets of analyses: standard logistic regression and propensity score weighted regression, to compare whether controlling for the selection effect had an impact on the results.

Finally, to study whether contraceptive use before the abortion might explain our results, we analysed current contraceptive use of women who had ever had an abortion, controlling for contraceptive use before their latest abortion. Propensity scores were not needed here, as they control for selection into who had an abortion, and all women in this model had had one.

Results

Descriptive statistics

Russian (40%) and Kurdish (26%) women had more often experienced an abortion compared with women in the general population (17%) or with Somali women (11%) (Table 1). Contraceptive use was most prevalent among the general population (70%), followed by Russian (56%), Kurdish (51%) and Somali (17%) women. Somali and Kurdish populations were younger than the Russian and general populations. Somali women had the highest average number of children at the time of the interview (3.17) followed by Kurdish (2.05), the general population (0.95) and Russian women (0.90).

Somali women were often married, whereas the general population cohabited more compared with the immigrant groups (Table 1).

While women with a history of induced abortion more often used contraceptives than women with no such history in the general, Somali and Kurdish populations, the opposite was true among Russian women (Table 2). However, the wide confidence intervals (CIs) suggest these differences were not significant.

Multivariate analysis

The interaction between abortion and immigrant background was significant at the 10% level in the joint Wald test in the standard model (p=0.066) and in the propensity score weighted model (p=0.052) (Table 3). Figure 1a shows the marginal probabilities of contraceptive use calculated from the standard model and Figure 1b from the propensity score weighted model. While the results are similar in both models, controlling for (some) selection effects reduced the differences between the migrant groups. Among the general and Kurdish populations, women with a history of abortion were more likely to use contraception in the standard model (Figure 1a). In the propensity score weighted model, Kurdish women were the only group for which the CIs do not overlap between the 'never abortion' and 'ever abortion' groups (Figure 1b). Among Russian women, the point estimates in the weighted model were very close to each other, suggesting that while for the other groups history of abortion may increase the likelihood of contraceptive use, for Russian women that experience makes no difference (Figure 1b). Education, religion, or age at the time of immigration were not statistically significantly associated with contraceptive use. Age and time since having an abortion were negatively associated with the odds of using contraceptives -although the latter was not significant in the propensity score weighted model. Married and cohabiting women were more likely than women without a partner to use contraceptives, perhaps reflecting frequency of sexual activity.

Table 4 shows the odds of using modern contraceptives among women with a history of induced abortion. The interaction between migrant background and previous contraceptive use was significant at the 10% level in the joint Wald test (p=0.062).

While in all other groups having used contraceptives before the most recent abortion was positively associated with also using them after the abortion, this was not the case for Somali women. Their predicted probability of using contraception was 30% among those without prior use compared with 9% among those with prior use (Table 5).

However, due to the small sample size (n=88) these results are only indicative.

Discussion

Findings and interpretation

We examined whether women's sociocultural background interacts with the likelihood of adopting a modern contraceptive method after an abortion and found that there were indeed differences. The general population was more likely to use contraceptives compared with migrants. Women from immigrant backgrounds may find it challenging to understand the Finnish health care system, particularly if they lack the relevant language or literacy skills. Access to health care services should be improved among these groups. Negative attitudes towards contraception, desire for a large family, religious reasons, or spousal disagreement over family planning methods may also reduce contraceptive use among some migrants [START_REF] Regushevskaya | Contraceptive use and abortion among women of reproductive age in St. Petersburg, Russia[END_REF][START_REF] Degni | Attitudes towards and perceptions about contraceptive use among married refugee women of Somali descent living in Finland[END_REF][START_REF] Degni | Religious beliefs prevailing among Somali men living in Finland regarding the use of the condom by men and that of other forms of contraception by women[END_REF].

Descriptive statistics suggested that the effect of having had an abortion on current contraceptive use among Russian women may decrease the likelihood of using contraceptives, as has been shown previously [START_REF] Laanpere | Ethnic differences in factors associated with the use of contraception among 20-to 44-year-old women in Estonia and St. Petersburg, Russia[END_REF]. However, after controlling for selection, both groups had similar levels of contraceptive use. Thus, selection might have been behind the previous results. Some women of Russian origin may believe that contraceptive use is dangerous and therefore prefer using abortions to control family size [START_REF] Regushevskaya | Contraceptive use and abortion among women of reproductive age in St. Petersburg, Russia[END_REF].

The association between having had an abortion and increased current contraceptive use was particularly strong among Kurdish women. While those without a history of induced abortion had a relatively low contraceptive prevalence, those who had had an abortion had a similar contraceptive prevalence to that of the general population. This may suggest that the provision of post-abortion contraceptive counselling has an important effect on this group.

Among women with a history of induced abortion, having used contraceptives before the termination increased the likelihood of current contraceptive use, apart from Somali women. Fewer than one in 10 Somali women who had used contraceptives prior to the termination adopted a method after an abortion, compared with 30% among those who did not use a method before the abortion. These women may benefit from tailored postabortion counselling that takes into account their sociocultural background and informs them about the available methods and their possible side effects [START_REF] Schunmann | Specialist contraceptive counselling and provision after termination of pregnancy improves uptake of long-acting methods but does not prevent repeat abortion: a randomized trial[END_REF][START_REF] Jones | Contraceptive use among U.S. women having abortions in 2000-2001[END_REF][START_REF] Pavlish | Somali immigrant women and the American health care system: discordant beliefs, divergent expectations, and silent worries[END_REF].

Strengths and weaknesses of the study

The strengths of the study include reliable abortion data that do not suffer from underreporting, which is common in surveys [START_REF] Jones | Underreporting of induced and spontaneous abortion in the United States: an analysis of the 2002 National Survey of Family Growth[END_REF]. Not many datasets allow for a reliable comparison of abortion and contraceptive use between the general and immigrant populations. Combining survey and register data is one of the main strengths of this study.

The study had some limitations. Propensity score weighted regressions have been criticised for having potential bias and for their standard errors becoming too small [START_REF] Freedman | Weighting regressions by propensity scores[END_REF].

We show both standard and propensity score weighted results. There were no large differences between the two, which may indicate that selection was not important or that the model creating the propensity scores omitted important variables. Therefore, we are cautious about interpreting these results in a strictly causal manner. We also had no information about pregnancy intentions. Some women may not use contraceptives because they are trying to conceive or are ambivalent about their pregnancy desires [START_REF] Frost | Factors associated with contraceptive use and nonuse, United States, 2004[END_REF][START_REF] Jones | Using longitudinal data to understand changes in consistent contraceptive use[END_REF]. Moreover, the data on the use of contraceptives before and after abortion were self-reported, which may result in misreporting method use. This limitation applies to all studies using survey data. Finally, the sample size was relatively small, which is common in studies of immigrant populations but may compromise the statistical power of the analysis.

Differences and similarities in relation to other studies

Few studies have been able to investigate contraceptive use and abortion using reliable data in a single study, because reliable data on abortion, such as medical registers, often do not include comprehensive information about contraceptive use. Our study contributes to these gaps in the literature using an innovative research design. There is also a shortage of previous research examining contraceptive use after an abortion.

Similarly to previous studies [START_REF] Moreau | Patterns of contraceptive use before and after an abortion: results from a nationally representative survey of women undergoing an abortion in France[END_REF][START_REF] Srikanthan | Religious and cultural influences on contraception[END_REF], differences in contraceptive use patterns were found depending on sociocultural background. However, as discussed above, we did not find that having had an abortion decreased the likelihood of current contraceptive use among Russian women, as a previous study found [START_REF] Laanpere | Ethnic differences in factors associated with the use of contraception among 20-to 44-year-old women in Estonia and St. Petersburg, Russia[END_REF].

Open questions and future research

Future research is needed for better understanding of issues specific to Somali women, to reduce the barriers in using a contraceptive method before and after an abortion. The reasons why contraceptive uptake was particularly high among Kurdish women after an abortion require more research. Data on pregnancy intentions should be collected so that women not using contraceptives because they are trying to conceive could be excluded from the sample in future studies of contraceptive use.

Recommendation for clinicians and policy-makers

These results are of interest to policy-makers and health care professionals who wish to improve the sexual and reproductive health of the immigrant populations in Finland.

Our results show that the likelihood of using contraception after an abortion differs between each immigrant group and the general population, and that these groups may benefit from different kinds of contraceptive counselling after abortion and easier access to services. with 95% CIs (controlling for variables in Table 3).

Figure 1 .

 1 Figure 1. Predicted probabilities of using any modern contraception by history of induced abortion and immigrant group from (A)standard logistic regression (sig. of the interaction effect p=0.066) and (B) propensity score weighted regression (sig. of the interaction effect p=0.052)

Table 1 .

 1 Distribution of sociodemographic characteristics by immigrant background (unweighted n=658).

	Characteristic	General population	Russian	Somali	Kurdish
		(n=187)	(n=183)	(n=124)	(n=164)
	Ever had an abortion, %	16.7	39.5	11.0	25.5
	Use of contraception, %	70.4	56.0	17.1	51.0
	Education, % a
	Less than upper secondary	22.8	17.0	78.8	56.8
	At least upper secondary	77.2	83.0	21.2	43.2
	Age, % a
	18-24	12.0	19.4	34.1	20.1
	25-29	11.1	27.3	18.4	19.5
	30-34	28.8	14.0	17.1	21.1
	35-39	18.8	22.7	15.4	17.9
	40-44	29.3	16.5	15.0	21.5
	Mean parity, n	0.95	0.90	3.17	2.05
	Relationship status, % a
	Single	29.5	24.9	20.3	21.9
	Married	36.5	43.5	65.4	52.0
	Cohabiting	27.8	16.1	1.4	12.3
	Separated/divorced/widowed	6.2	15.5	12.9	13.7
	Mean no. of years since abortion b	5.4	3.7	2.7	2.7
	Used contraceptives before abortion, % b	65.0	52.3	62.7	49.3
	Immigrated after age 16, % c	n/a	65.7	50.2	75.7
	Muslim faith, % c	n/a	0.03	95.3	60.5

a Column percentages total 100%. b Includes only those who had ever had an abortion. c Includes only migrant women. n/a, Not available.

Table 2 .

 2 Percentage of women using contraceptives by immigrant background and history of induced abortion.

	Group	No abortion	95% CI	Abortion	95% CI
	General population	68.6	60.7, 76.5	79.2	65.4, 93.0

Table 3 .

 3 Likelihood of using any form of modern contraception: logistic regression with and without propensity score weights (n=609).

	Variable	Category	Odds ratio
			Standard	ATT
	History of induced abortion	Never abortion (ref.)	1.00	1.00
		Ever abortion	10.2*	7.30*
	Group	General population (ref.)	1.00	1.00
		Russian	0.45*	0.41 †
		Somali	0.04***	0.04***
		Kurdish	0.28**	0.25*
	Interaction: immigrant group	Ever abortion x Russian	0.15* a	0.15* b
	and abortion
		Ever abortion x Somali	0.47	0.52
		Ever abortion x Kurdish	0.45	0.62
	Age		0.94**	0.92**
	Education	Less than upper secondary	1.00	1.00
		education (ref.)
		At least upper secondary	1.07	0.95
		education
	Birth history	Parity	1.21**	1.07
	Relationship status	Single (ref.)	1.00	1.00
		Married	2.89***	5.18***
		Cohabiting	3.49***	6.80***
		Separated/divorced/widowed	1.02	1.33
	Religion	Native or other faith (ref.)	1.00	1.00
		Muslim	0.75	0.65
	Migration history	Native or moved before age 16 1.00	1.00
		Moved after age 16	1.20	1.29
	Years since abortion		0.90*	0.92
	†p<0.1, *p<0.05, **p<0.01, ***p<0.001.
	Interaction: a p=0.066, b Interaction p=0.052.

Table 4 .

 4 Likelihood of using any form of modern contraception among those who had an abortion: logistic regression with and without propensity score weights (n=88).

	Variable	Category	Odds
			ratio
	Contraceptive use preceding most recent	Did not use (ref.)	1.00
	abortion
		Used a method	4.61
	Group	General population (ref.)	1.00
		Russian	0.01*
		Somali	0.04 †
		Kurdish	0.12
	Interaction: immigrant group and	Used a method x Russian	1.25
	contraceptive use a
		Used a method x Somali	0.02 †
		Used a method x Kurdish	0.64
	Age		0.79**
	Education	Less than upper secondary education (ref.) 1.00
		At least upper secondary education	1.01
	Birth history	Parity	0.86
	Relationship status	Single	1.00
		Married	57.4**
		Cohabiting	97.9**
		Separated/divorced/widowed	5.60
	Religion	General population or other faith (ref.)	1.00
		Muslim	0.43
	Migration history	Native or moved before age 16	1.00
		Moved after age 16	4.11*
	Years since abortion		0.98
	†p<0.1, *p<0.05, **p<0.01.
	(a) Sig. of the interaction p=0.062.

Table 5 .

 5 Predicted probabilities of current contraceptive use by prior contraceptive use based on model in Table 4 (n=88).

	Group	Did not use (95% CI)	Used (95% CI)
	General population	0.71 (0.37, 1.04)	0.84 (0.69, 1.00)
	Russian	0.16 (0.03, 0.29)	0.36 (0.16, 0.56)
	Somali	0.30 (-0.02, 0.61)	0.09 (-0.03, 0.21)
	Kurdish	0.44 (0.19, 0.69)	0.58 (0.37, 0.79)

Acknowledgements

The authors would like to thank Minna Säävälä for her contributions at the early stages of the manuscript.

Funding

This research received no specific grant from any funding agency in the public, commercial or not-for-profit sectors. The Maamu data collection was funded by the Social Insurance Institution of Finland (KELA), European Social Fund (ESF) and the Finnish Work Environment Fund.

Disclosure statement

The authors have no conflicts of interest to declare.

Appendix Methods

Our model estimates whether having an abortion is associated with current contraceptive use, while controlling for a range of adjustment variables (eq. 1).

𝑙𝑙𝑙𝑙𝑙𝑙𝑙𝑙𝑙𝑙(𝑌𝑌) �

where D is the experience of abortion and X2-Xk are the adjustment variables.

This model was weighted using propensity scores to balance the population so that the group who had never had an abortion resembled the group who had, in terms of baseline characteristics preceding the abortion experience. The propensity score is a predicted probability from a logistic regression model, where the baseline characteristics predict the likelihood of having an abortion.

where 𝑝𝑝̂𝑖𝑖 is the propensity score and 𝑥𝑥 𝑏𝑏 a vector of the baseline characteristics.

We calculated ATT weights, which leave the group that experienced an abortion unaltered (eq. 3). Those who had never had an abortion were weighted with propensity scores to cancel the selection effect by making the baseline characteristics of this group similar to those of the abortion group (eq. 4).

𝐹𝐹𝑙𝑙𝐹𝐹 𝑑𝑑 𝑖𝑖 = 1:

𝐹𝐹𝑙𝑙𝐹𝐹 𝑑𝑑 𝑖𝑖 = 0: 𝑤𝑤 𝑖𝑖,𝐴𝐴𝐴𝐴𝐴𝐴 = 𝑝𝑝î𝑖 1 -𝑝𝑝î𝑖 (4) logistic regression).