HIV and Syphilis Coinfection in Pregnancy and Adverse Birth Outcomes in Uganda

Despite increasing global syphilis incidence, little is known about the combined impact of maternal HIV and syphilis coinfection. We evaluated effects of HIV/syphilis coinfection in pregnancy on birth outcomes.

We conducted 2 prospective birth cohort studies in Uganda from 2017 to 2023. Our primary outcome was birthweight. Our secondary outcome was a composite adverse birth outcome (birthweight <2.5 kg, stillbirth, early neonatal death, or 5-min APGAR<7). We compared outcomes by HIV and Treponema pallidum particle agglutination assay (TPPA) seropositivity and fitted multivariable regression models.

Treponema pallidum particle agglutination assay seroprevalence was 12% (118/967); 19% (94/483) among WHIV and 5% (24/484) among women without HIV. Only 48% of TPPA-seropositive women reported syphilis testing during antenatal care. Stillbirth and early neonatal death were higher among TPPA seropositive (12%, 15/118) than seronegative (4%, 32/849) participants. Low birthweight was associated with HIV seropositivity (-0.1 kg, 95% CI -0.15, -0.04), younger maternal age (0.01 kg per year, 95% CI 0.01, 0.02), and lower gestational age (0.07 kg per week, 95% CI 0.06, 0.09) but not TPPA serostatus. The composite outcome was associated with lower maternal and gestational age.

We report high TPPA seroprevalence, low syphilis testing rates, and associations with adverse birth outcomes, emphasizing the need to improve prenatal syphilis testing and treatment.