Uptake and Timing of Viral Load Testing and Frequency of Viraemic Episodes During Pregnancy in South Africa

Background: Repeated monitoring of viral load (VL) among pregnant women living with HIV (WLWH) is critical in vertical transmission prevention. For women who are newly diagnosed with HIV during pregnancy, a subsequent VL is recommended three months after ART initiation, and for all women living with HIV, follow-up VL is required every six months throughout pregnancy and breastfeeding. Here, we describe the uptake and timing of VL testing and frequency and distribution of viraemic episodes during pregnancy. Methods: We linked prospective cohort data from WLWH whose infants were born at Rahima Moosa Mother and Child Hospital (RMMCH) in Johannesburg, South Africa (2013-2018) to laboratory data from the National Health Laboratory Services national HIV cohort. We report the uptake and timing of VL testing, and frequency of viremia and viral suppression. We applied the log binomial regression, to explore factors associated with having at least one or more VL test. Crude relative risks (RR) and adjusted relative risks (aRR) with 95% confidence intervals (CI) relative risk were reported. Results: Data from 4064 women with known dates of entry into antenatal care and delivery during the study period were analysed. Overall, less than half (46%) completed VL testing during pregnancy. Most VLs were conducted during the third trimester (67%). Only 5% (n = 100) were during the first trimester and 11% within 7 days of delivery. Three-quarters of tests during pregnancy indicated viral suppression (VL < 400 copies/mL), 7% viraemic (VL 400-1000 copies/mL), and 19% high-grade viraemia (VL > 1000 copies/mL). We found that being older (≥35) and being engaged in HIV care prior to pregnancy were significantly associated with VL testing during pregnancy. Conclusion: With less than half of pregnant women living with HIV in this study having a VL measure during their pregnancy, and VL testing occurring late in pregnancy, this study highlights critical gaps in providing quality HIV care to women and prevention of vertical transmission.