Abstract
INTRODUCTION: Achieving and maintaining viral suppression (VS) during pregnancy and breastfeeding is central to preventing vertical transmission and optimizing maternal health. High rates of VS have been demonstrated among adult and paediatric populations receiving tenofovir-lamivudine-dolutegravir (TLD), but VS and viraemia among pregnant and postpartum women with HIV (WHIV) in high-burden settings have not been well-documented. METHODS: Between September 2021 and December 2023, pregnant WHIV, ≤18 weeks gestation, were enrolled in antenatal care (ANC) and followed postpartum in Cape Town, South Africa. WHIV received HIV care in routine health services and continued, switched to or initiated TLD at ANC entry. VS was defined as viral load (VL) <50 copies/ml; viraemic episodes (VEs) were categorized as major (>1000 copies/ml) or minor (50-1000 copies/ml). Mixed-effects Poisson regression models were fit to assess factors associated with major VE risk. RESULTS: Among 763 WHIV with ≥1 VL, median age was 30 years (interquartile range [IQR] 25-34) and median gestation was 14 weeks at enrolment (IQR 11-17); 89% were on antiretroviral therapy, including 74% on TLD. Overall 99% achieved ≥1 VL<50 copies/ml: 73% sustained VS through 48 weeks postpartum, with 16% having ≥1 minor VE and 15% ≥1 major VE. At enrolment, 77% of VL measures were <50 copies/ml, increasing to >90% during pregnancy through 12 weeks postpartum and declining to 81% by 24 weeks postpartum. In multivariable analysis, each additional year of age conferred a 6% (95% confidence interval [CI] 0.89, 0.98, p = 0.006) lower risk of subsequent major VE after achieving VS. WHIV with viraemia (50-1000 copies/ml) at enrolment were 3.6 (95% CI 1.94, 6.70, p<0.001) times more likely to have a subsequent major VE, whereas CD4+>500 cells/mm lowered major VE risk by 53% (95% CI 0.32, 0.89, p = 0.016). CONCLUSIONS: High rates of VS were maintained during pregnancy and early postpartum, but substantial viraemia emerged by 24 weeks postpartum, jeopardizing maternal and child health outcomes. These unique data provide further impetus to explore innovative approaches to supporting adherence among WHIV during the postpartum period.