Contraceptive non-use and emergency contraceptive use at first sexual intercourse among nearly 12 000 Scandinavian women SONIA GULERIA1 , KIRSTEN E. JUUL1 , CHRISTIAN MUNK1 , BO T. HANSEN2 , LISEN ARNHEIM-DAHLSTRÖM3 , KAI-LI LIAW4 , MARI NYGÅRD2 & SUSANNE K. KJÆR1,5 1Unit of Virus, Lifestyle and Genes, Danish Cancer Society Research Center, Copenhagen, Denmark, 2Department of Research, Cancer Registry of Norway, Oslo, Norway, 3Department of Medical Epidemiology and Biostatistics, Karolinska Institute, Stockholm, Sweden, 4Epidemiology, Merck Research Laboratories, Kenilworth, NJ, USA, and 5Department of Gynecology, Rigshospitalet University Hospital, University of Copenhagen, Copenhagen, Denmark ACTA Obstetricia et Gynecologica Scandinavica Journal Club -Gynecology- March 2017 Edited by Francesco D’Antonio

Background The prevalence of sexually transmitted infections (STIs) is high in Scandinavian countries. Although several contraceptive methods are available to prevent pregnancy, only barrier contraceptives, such as condoms, offer significant protection against STIs. The prevalence of emergency contraceptive pill (ECP) use, also known as the “morning after pill,” has increased among adolescents in recent years. Preventive behaviors adopted at an early age are shown to be strong determinants of subsequent healthy behaviors; contraceptive non-use at first sexual intercourse (FSI) is associated with non-use in subsequent sexual encounters and more episodes of STIs in later life. Previous studies have identified socio-demographic and lifestyle factors such as woman and partner’s age, education and smoking to be associated with contraceptive non-use at FSI. However some of these studies are older, have a small sample size and a low response rate, reducing generalizability of their results.

Aims of the study To describe patterns of contraceptive use at FSI among Scandinavian women. To examine whether selected factors are associated with non-use and emergency contraceptive pill use at first sexual intercourse, among 18- to 26-year-old women from Denmark, Norway and Sweden.

Methodology Study design: Cross-sectional population-based questionnaire study carried out in Denmark, Norway and Sweden, A random sample of 18- to 45-year-old women were asked to answer a self-administered questionnaire. Information on socio-demography and behaviors related to sex, contraceptives and lifestyles was collected via a paper-based questionnaire, web or phone interview. Exclusion criteria: Women who did not use contraceptives, and women who reported using methods such as ‘safe periods’ or ‘withdrawal’ at FSI. Statistical analysis: The prevalence of contraception methods used at first sexual intercourse was calculated. Factors associated with contraceptive non-use and emergency contraceptive pill use at first sexual intercourse were determined using log binomial models.

Results (1) 11 627 women were included in the study. Women who did not use contraceptives, and women who reported using methods such as ‘safe periods’ or ‘withdrawal’ at FSI, were then excluded from the analysis on ECP use, leaving 9782 women in this analysis.

Results (2) Overall contraceptive non-use at FSI was reported by 9.6%, 14.1% and 16.6% of 18- to 26-year-old Danish, Norwegian and Swedish women, respectively. The country-specific prevalence of ECP use at FSI was 2.1% for Denmark, 4.4% for Norway and 4.5% for Sweden. Condom use was the most preferred contraceptive method (63.0% among women in Denmark, 55.3% in Norway and 63.1% in Sweden). Dual use of condom and hormonal contraceptives at FSI was most prevalent in Denmark (13.7%), followed by Norway (9.7%) and Sweden (5.5%).

Results (3) The patterns of contraceptive non-use were similar in all three countries, with Denmark having the lowest prevalence in all categories. Non-use slightly decreased with decreasing age at response and was lowest among the youngest women (18–19 years: 8.9% in Denmark, 11.0% in Norway and16.5% in Sweden). There was a decrease in contraceptive non-use with higher education, such that women with a higher education had a lower prevalence of non-use (> high school education: 8.6% in Denmark,13.3% in Norway and 16.2% in Sweden).

Results (4) Women who had FSI at either an early age (≤12 years) or late age (21–25 years) had a higher risk of non-use than those who had FSI between 15 and 16 years of age (PR 3.25 and PR 2.00, respectively). After additional adjustment for partner’s age at woman’s FSI, only early age at FSI of the woman implied an increased risk of non-use of contraception at first intercourse The risk of non-use of contraception at FSI increased with increasing age of the first partner. No association with non-use of contraception at FSI if the woman was older than the partner. Women with an older partner had a higher risk of non-use at FSI.

Results (5) For women who started to smoke prior to, or in the same year as, their FSI, the risk of being a non-user was approximately 1.7 times higher than for women who had never smoked at the time of their FSI. No statistically significant association between the initiation of alcohol consumption and contraceptive non-use at FSI.

Results (6) Women who had FSI at age 17 years or later had higher risk of ECP use compared with women with FSI at age 15–16 years. The risk of ECP use increased for women who had FSI with a partner 20 years or older. The risk of ECP use at FSI was significantly higher among women whose first partner was at least five years older, compared with women with a partner of the same age. Alcohol initiation relative to FSI was significantly associated with ECP use. Women who started smoking in the same year as their FSI had a nearly 1.5 times higher risk of using ECP at their FSI

Strengths Limitations Large, random, population-based sample. High participation rate (60%). Ascertainment of the effect of alcohol initiation prior to FSI on the likelihood of contraceptive non-use and ECP use at FSI. The examination of ECP use at FSI in the Scandinavian countries adds new knowledge that may be relevant for sexual health education and policy making. Limitations Social desirability bias, which arises when the respondents report what seems more favorable than what is actually true. The likelihood of less precise recollection of an event (for example FSI) among women who experienced it long ago compared with women who experienced it recently. Differential socio-economic characteristics of participating and non-participating women may have resulted in reduced generalizability. Some potential confounders such as contraceptive education, counseling and discussions with teachers, parents or physicians were not assessed and may have biased the results, as these factors were shown to play a role in adolescent’s decisions to practice safe sex in previous studies.

Conclusion Contraceptive non-use at first sexual intercourse is strongly associated with early age at first sexual intercourse. Emergency contraceptive pill and contraceptive non-use at first sexual intercourse are both strongly associated with increasing partner age and an increasing difference in age between the woman and her partner. To decrease STIs and unintended pregnancies, young women should be educated to initiate contraceptive discussions, and to acquire skills to effectively communicate contraceptive preferences and intentions to partners.