Objectives: To determine the impact of time between initiating highly active antiretroviral therapy (HAART) and delivery—duration of antenatal HAART—on perinatal HIV infection.
Design: We conducted a retrospective cohort analysis of pregnant HIV-infected women in Lusaka, Zambia. Women in our cohort were receiving HAART and had an infant HIV polymerase chain reaction test between 3 and 12 weeks of life.
Methods: We examined factors associated with infant HIV infection and performed a locally weighted regression analysis to examine the effect of duration of antenatal HAART on perinatal HIV infection.
Results: From January 2007 to March 2010, 1813 HIV-infected pregnant women met inclusion criteria. Mean gestational age at first antenatal visit was 21 weeks (SD ± 6), median CD4+ cell count was 231 cells per microliter (interquartile range: 164-329), and median duration of antenatal HAART was 13 weeks (interquartile range 8-19). Fifty-nine (3.3%) infants were HIV infected. Duration of antenatal HAART was the most important predictor of perinatal HIV transmission. Compared with women initiating HAART at least 13 weeks before delivery, women on HAART for ≤4 weeks had a 5.5-fold increased odds of HIV transmission (95% confidence interval: 2.6 to 11.7). Locally weighted regression analysis suggested limited additional prophylactic benefit beyond 13 weeks on antenatal HAART.
Conclusions: Low rates of mother-to-child HIV transmission can be achieved within programatic settings in Africa. Maximal effectiveness of prevention of mother-to-child transmission programs is achieved by initiating HAART at least 13 weeks before delivery.
From the *University of Alabama at Birmingham School of Medicine, Birmingham, AL; †Centre for Infectious Disease Research in Zambia, Lusaka, Zambia; and ‡University Teaching Hospital, Lusaka, Zambia.
Received for publication February 4, 2011; accepted June 7, 2011.
Trainee support was provided by the National Institutes of Health through the International Clinical Research Fellows Program at Vanderbilt University (R24 TW007988) and the Vanderbilt-CIDRZ AIDS International Research and Training Program (D43 TW001035). Additional investigator salary was provided through a Clinical Scientist Development Award from the Doris Duke Charitable Foundation (2007061).
Data presented in this article were presented, in part, at the XVIIIth International AIDS Conference and published as abstract MOPE0261.
The authors C.J.C. designed and interpreted the analysis, drafted the article, and substantially revised it. M.J.G. analyzed study data, interpreted the analysis, and substantially revised the article. N.P., N.C., J.M., and B.J.D. participated in data interpretation and article revision. B.H.C., J.S.A.S., and E.M.S. designed the analysis, interpreted the analysis, and substantially revised the article.
The authors have no conflicts of interest to disclose.
Correspondence to: Carla Chibwesha, MD, MSc, Centre for Infectious Disease Research in Zambia, PO Box 34681, Lusaka, Zambia (e-mail: Carla.Chibwesha@cidrz.org).