PROJECT SUMMARY Pregnant and postpartum women in the Africa region are at high risk for acquiring curable sexually transmitted infections (STIs) that can have in devastating health consequences, including increased risk of HIV infection and transmission. Theory and empirical evidence suggest that intimate partner violence (IPV) is an important risk factor that may contribute to sexual risk among women. Relatively few studies, however, have examined relations between IPV and sexual risk during pregnancy and postpartum, a critical phase in the life of women and their newborn babies. Further, nearly all of the extant research on the link between IPV and sexual risk among women suffers from serious methodological limitations that constrain understanding of the specific nature of the association. For example, most studies of relations between IPV and STIs or STI-risk behaviors have examined global associations at one point in time using binary measures of physical and/or sexual abuse. This approach precludes the ability to determine temporality of associations and/or to examine heterogeneity in the types, levels, and chronicity of women's experiences of IPV that may differentially predict risk of STI. Pregnant women who have experienced chronic multiform abuse in conjunction with controlling behavior may be more at greater risk for STI during the postpartum period, compared to women who experience other types of violence profiles. In addition, no research, to our knowledge, has examined theoretical mechanisms that may explain relations between IPV and postpartum sexual risk and/or determined whether pathways may differ for HIV-positive compared to HIV-negative women. The objective of the proposed study is to determine whether, why, and for whom experiencing a particular type or pattern of IPV prior to or during pregnancy is associated with postpartum sexual risk (incident STI infection, inconsistent condom use). Data will come from a longitudinal cohort study of HIV-positive and HIV-negative pregnant women who sought antenatal services from a primary health clinic in Durban, South Africa (N=1480; 39% HIV-positive). Study participants completed behavioral assessments during pregnancy at the first antenatal visit (T1) and at 14 weeks (T2) and 9 months postpartum (T3); STIs were assessed and treated at T1 and T2. Latent class, mediation, and moderated mediation analyses will be used to: (1) identify subgroups of women at T1 based on their patterns of experience with psychological, physical, and sexual IPV, as well as their reports of controlling behavior by their current partner (IPV profiles), and examine prospective associations between these IPV profiles and postpartum sexual risk (incident STI infection, inconsistent condom use); (2) determine whether emotional distress and/or low sexual relationship power mediate associations, and (3) examine whether and how associations differ for HIV-positive and HIV-negative women. Findings will provide a nuanced and comprehensive view of relations between IPV and postpartum sexual risk that will inform the development of targeted prevention strategies to reduce sexual risk during this critical life phase.