Thomson KA, et al. - In order to inform HIV-1 prevention strategies for women during pregnancy and postpartum, they sought to assess the understanding regarding the absolute and relative risk of HIV-1 acquisition during pregnancy and postpartum. A steady increase in the HIV-1 acquisition probability per condomless sex act was observed through pregnancy. This risk was highest during the postpartum period. Findings thereby suggested that biological changes during pregnancy and postpartum increase female HIV-1 susceptibility.