Sexually transmitted infections and bacterial vaginosis and preterm birth in pregnant people living with HIV: A population-based cohort study

Background While individual sexually transmitted infections are linked with preterm births, their synergistic impact among pregnant people living with HIV (PLWH) remain unclear. We aimed to identify the impact of antenatal sexually transmitted infections and bacterial vaginosis on preterm birth in PLWH. Methods We completed a population-based cohort study using the British Columbia Perinatal HIV Surveillance Database, capturing all births in PLWH from January 1997 to December 2022. Univariate risk factors for preterm birth were identified using chi-squared tests, Fisher's exact tests and t-tests, followed by a multivariate logistic regression analysis. Results Of 578 singleton pregnancies, 111 (19.2%) had preterm births, of which 34 (31%) delivered before 34 weeks gestational age. In our population, 11% were identified with a sexually transmitted infection or bacterial vaginosis (STIBV) in pregnancy. The preterm birth rate in PLWH with antenatal STIBV was 37% compared to 17% in PLWH without STIBV (OR: 2.18; 95% CI (1.50 - 3.16); p = .0003). Preterm deliveries were more common in individuals with concurrent Hepatitis C (OR: 2.42; p < .0001), antenatal diagnosis of Chlamydia trachomatis (OR 2.17; p = .036), Trichomonas vaginalis (OR: 2.78; p < .001) and bacterial vaginosis (OR: 2.15; p = .003). After adjusting for ethnicity, history of preterm birth, substance use, concurrent Hepatitis C, CD4 count and viral suppression at delivery, STIBV remains an independent risk factor (OR: 2.09; 95% CI: 1.04 - 4.19; p = .039). Conclusion Among PLWH, antenatal screening for sexually transmitted infections and bacterial vaginosis can identify individuals at the highest risk of preterm birth.