Decrease of condom use in heterosexual couples and its impact on pregnancy rates: the Swiss HIV Cohort Study (SHCS)

Introduction: Following the ‘Swiss statement’ in 2008 it became an option to omit the use of condoms in serodiscordant couples and to conceive naturally. We analysed its impact on condom use and pregnancy events. Methods: In all, 3023 women (aged 18–49 years) participating in the Swiss HIV Cohort Study were included. Observation time was divided into pre- and post-Swiss statement phases (July 2005–December 2008 and January 2009–December 2019). We used descriptive statistics, Poisson interrupted time series analysis for pregnancy incidence, and logistic regression to identify predictors of live births, spontaneous and induced abortions. Results: Condomless sex in sexually active women increased from 25% in 2005 to 75% in 2019, while pregnancy incidence did not. Women after 2008 experienced higher spontaneous abortion rates (12.1% vs. 17.2%, p = 0.02) while induced abortion and live birth rates did not change significantly. Spontaneous abortions were more common in older women [adjusted odds ratio (aOR) = 1.4, 95% CI: 1.2–1.7, p < 0.001], in women consuming alcohol (aOR = 2.8, 95% CI: 1.9–4.1, p < 0.001) and in those with non-suppressed viral load (aOR = 0.2, 95% CI: 0.1–0.4, p ≤ 0.001). Induced abortions were more likely in women with depression (aOR = 3.4, 95% CI: 1.8–6.3, p < 0.001) and non-suppressed viral load (aOR = 0.3, 95% CI: 0.2–0.7, p = 0.003). Conclusions: The publication of the Swiss statement resulted in more condomless sex in heterosexual women, but this did not result in a higher incidence of pregnancy. Maternal age and spontaneous abortion rates increased over time, while induced abortion rates were not significantly affected. Women living with HIV in Switzerland have an unmet need regarding family planning counselling.