Limited risk of drug resistance after discontinuation of antiretroviral prophylaxis for the prevention of breastfeeding transmission of HIV.

We evaluated 70 HIV-infected pregnant women with CD4⁺ cell count >350 cells per cubic millimeter who received zidovudine, lamivudine, and nevirapine from week 25 of gestation until 6 months after delivery and a 3-week tail of zidovudine and lamivudine at the moment of drug discontinuation. Forty days after the interruption of all drugs resistance mutations were present in 5 of 70 (7.1%) women. Two of them had the same mutation archived in baseline HIV DNA. The other 3 women had, at least once, detectable viral load and presence of mutations during treatment. Overall, the risk of developing resistance mutations in compliant women was low.