Plasma viraemia in HIV‐positive pregnant women entering antenatal care in South Africa

Introduction Plasma HIV viral load (VL) is the principle determinant of mother‐to‐child HIV transmission (MTCT), yet there are few data on VL in populations of pregnant women in sub‐Saharan Africa. We examined the distribution and determinants of VL in HIV‐positive women seeking antenatal care (ANC) in Cape Town, South Africa. Methods Consecutive HIV‐positive pregnant women making their first antenatal clinic visit were recruited into a cross‐sectional study of viraemia in pregnancy, including a brief questionnaire and specimens for VL testing and CD4 cell enumeration. Results & discussion Overall 5551 pregnant women sought ANC during the study period, of whom 1839 (33%) were HIV positive and 1521 (85%) were included. Approximately two‐thirds of HIV‐positive women in the sample ( n =947) were not on antiretrovirals at the time of the first ANC visit, and the remainder (38%, n =574) had initiated antiretroviral therapy (ART) prior to conception. For women not on ART, the median VL was 3.98 log 10 copies/mL; in this group, the sensitivity of CD4 cell counts ≤350 cells/µL in detecting VL>10,000 copies/mL was 64% and this increased to 78% with a CD4 threshold of ≤500 cells/µL. Among women on ART, 78% had VL<50 copies/mL and 13% had VL >1000 copies/mL at the time of their ANC visit. Conclusions VL >10,000 copies/mL was commonly observed in women not on ART with CD4 cell counts >350 cells/µL, suggesting that CD4 cell counts may not be adequately sensitive in identifying women at greatest risk of MTCT. A large proportion of women entering ANC initiated ART before conception, and in this group more than 10% had VL>1000 copies/mL despite ART use. VL monitoring during pregnancy may help to identify pregnancies that require additional clinical attention to minimize MTCT risk and improve maternal and child health outcomes.