Postpartum Virologic Failure Among Women with HIV Suppressed at Delivery in Spain: Incidence, Timing, and Associated Factors.

The postpartum period remains a vulnerable phase for maintaining virologic suppression among women with HIV (WWH); however, evidence on postpartum virologic failure (VF) among women virologically suppressed at delivery is limited. We analyzed data from the CoRIS cohort including WWH aged 18-50 years who had a live birth while receiving antiretroviral therapy (ART) and were virologically suppressed at delivery between 2004 and 2024. The primary outcome was time to VF within 12 months postpartum, defined as two consecutive HIV RNA measurements >50 copies/mL or a single measurement >1000 copies/mL. Secondary outcomes included virologic non-suppression (VnS) and CD4+ cell count changes at 12 months postpartum. Kaplan-Meier and Cox models were used to assess time to VF and generalized estimating equations (logistic and linear model) to evaluate VnS and CD4+ changes, accounting for repeated deliveries. The analysis included 422 deliveries among 337 women. The cumulative incidence of VF was 15.7% (95% CI: 12.1-19.1) at 12 months postpartum. VF risk was lower in more recent calendar periods. At 12 months postpartum, 18.0% of deliveries showed VnS. Earlier calendar periods, younger maternal age, and protease inhibitor-based ART regimens were associated with higher odds of non-suppression. Mean CD4+ cell counts increased by 88.5 cells/µL overall, with greater improvements in more recent years. Postpartum ART discontinuation decreased markedly over time, alongside increasing treatment stability. Maintaining virologic suppression postpartum remains challenging despite advances in ART. Targeted postpartum strategies are needed to ensure durable virologic control.