Decrease of condom use in heterosexual couples and its impact on pregnancy rates: the Swiss HIV Cohort Study (SHCS). HIV Medicine
Hachfeld and Atkinson et al. assessed the influence of the “Swiss statement” proclaiming the safety of condomless sex in virally suppressed HIV serodiscordant couples on condom use and obstetric events, and examined risk factors for spontaneous and induced abortions in the SHCS.
Heterosexual women between 18 and 49 years of age with follow-up between July 2005 and December 2019 were included. The observation period was divided into a phase before January 2009 (pre-Swiss statement), and a phase thereafter (post-Swiss statement). Authors assessed trends in pregnancy incidence over time using interrupted time series models, and identified predictors for spontaneous and induced abortions using multivariable logistic regression.
The study included 3’023 women. Condomless sex was reported by 25% of sexually active women in 2005 and by 75% in 2019. When comparing pre- and post-Swiss statement periods, the incidence of any obstetric event (6.5 per 100 person-years [PY], 95% CI 6.0-7.1 before vs. 6.9 per 100 PY, 6.4-7.3 thereafter) and live births (67.4% vs. 66.3%) remained stable. Induced abortions decreased from 20.5% before the Swiss statement to 16.4% thereafter (p = 0.07), and spontaneous abortions increased from 12.1% to 17.2% (p = 0.02). Compared with live births, spontaneous abortions were more likely in older women (adjusted odds ratio [aOR] 1.4 per 5 years increase, 95% CI 1.2-1.6), those with a stable sex partner (aOR 3.9, 1.5-10.2), those with a higher CD4 cound (aOR 1.1 per 100 cells/µL, 1.1-1.2), those on non-nucleoside reverse transcriptase inhibitors (aOR 1.7, 1.1-2.5) and those who consumed alcohol (aOR 2.8, 1.9-4.1), whereas spontaneous abortions were less likely in women with a suppressed HIV viral load (aOR 0.2, 0.1-0.4). Induced abortions were more likely in women with depression (aOR 3.4, 1.8-6.3) and those drinking alcohol (aOR 1.6, 1.0-2.4), and less likely among women with an undetectable HIV viral load (aOR 0.3, 0.2-0.7) and those receiving protease inhibitors (aOR 0.3, 0.2-0.5).
Taken together, the study shows that pregnancy rates remained stable despite increases in condomless sex following the Swiss statement. Spontaneous abortions slightly increased, which might reflect the ageing of SHCS cohort participants. Although small decreases in the rate of induced abortions over time were observed, they remained twice as high compared with those from HIV-negative women in Switzerland. These findings underline the importance of timely family planning counselling including the provision of safe and effective contraception.