Effects of highly active antiretroviral therapy duration and regimen on risk for mother-to-child transmission of HIV in Johannesburg, South Africa.

Background: Limited information exists about effects of different highly active antiretroviral therapy (HAART) regimens and duration of regimens on mother-to-child transmission (MTCT) of HIV among women in Africa who start treatment for advanced immunosuppression.

Methods: Between January 2004 to August 2008, 1142 women were followed at antenatal antiretroviral clinics in Johannesburg. Predictors of MTCT (positive infant HIV DNA polymerase chain reaction at 4-6 weeks) were assessed with multivariate logistic regression.

Results: Mean age was 30.2 years (SD = 5.0) and median baseline CD4 count was 161 cells per cubic millimeter (SD = 84.3). HAART duration at time of delivery was a mean 10.7 weeks (SD = 7.4) for the 85% of women who initiated treatment during pregnancy and 93.4 weeks (SD = 37.7) for those who became pregnant on HAART. Overall MTCT rate was 4.9% (43 of 874), with no differences detected between HAART regimens. MTCT rates were lower in women who became pregnant on HAART than those initiating HAART during pregnancy (0.7% versus 5.7%; P = 0.01). In the latter group, each additional week of treatment reduced odds of transmission by 8% (95% confidence interval: 0.87 to 0.99, P = 0.02).

Conclusions: Late initiation of HAART is associated with increased risk of MTCT. Strategies are needed to facilitate earlier identification of HIV-infected women.