Postpartum Resistance to HIV Drugs

Antiretroviral use during pregnancy prevents transmission of HIV from mother to infant, but some mothers subsequently develop drug resistance. How frequently does this happen, and what are the risk factors? To find out, investigators studied postpartum plasma samples from 146 previously treatment-naive HIV-infected women in the U.S. who received pregnancy-limited antiretrovirals between 1998 and 2005. HIV genotyping was performed using both standard population sequencing and allele-specific PCR (ASPCR); ASPCR has high sensitivity for low levels of virus harboring specific mutations.

Initial regimens consisted of AZT/3TC alone for 29% of the women, AZT/3TC + nelfinavir for 64%, and AZT/3TC + nevirapine for 7%. Twelve percent of the women who …