Improved Pregnancy Viral Load Monitoring but Persistent Postpartum Gaps After Guideline Changes: A Population-Based Analysis in the Western Cape, South Africa (2018–2024)

BACKGROUND: In South Africa, HIV treatment guideline changes implemented in 2020 introduced dolutegravir-based regimens and expanded viral load (VL) monitoring to include testing at delivery and 6 months postpartum for women on antiretroviral therapy (ART). We assessed temporal trends and factors associated with VL monitoring and outcomes among pregnant and postpartum women with HIV in the Western Cape. METHODS: We included women with HIV with live births from 2018-2024 who initiated ART before or during pregnancy. We used routinely-collected healthcare data to assess VL monitoring at (i) delivery or third trimester ("late pregnancy"), and (ii) postpartum (<8 months after delivery). VL categories were defined as <50, 50-999, and ≥1,000 copies/ml. We examined predictors of VL testing coverage and viral suppression using modified Poisson GEE and multinomial logistic regression models, including policy period, maternal age, parity, and ART timing . RESULTS: Among 88,415 deliveries to 80,095 women: 74% received ART before pregnancy and 26% started ART during pregnancy. From 2018-2024, late-pregnancy VL testing coverage increased: 69%-91% (aRR=1.28, 95%CI 1.26-1.29); whereas postpartum testing coverage declined: 51%-43% (aRR=0.96, 95%CI 0.94-0.97). The proportion of women with late-pregnancy VL<50 increased from 73-80% (2018-2024), while VL 50-999 declined from 14%-8%. ART interruptions before or during pregnancy, younger age and higher parity were predictors of lower VL testing coverage and poorer virological outcomes. CONCLUSION: Updated ART guidelines improved late-pregnancy but not postpartum VL testing coverage. Dolutegravir introduction was associated with improved viral suppression <50 copies/ml. Persistently low postpartum coverage suggests substantial gaps in retention and/or VL testing.