BackgroundRegardless of their HIV serostatus, mothers are advised to exclusively breastfeed infants ≤6 mo postpartum. How this guidance impacts breast milk intake among HIV-exposed infants in varied contexts needs to be better understood. ObjectivesThe objective of this study was to compare breast milk intake of HIV-exposed and HIV-unexposed infants at 6 wk and 6 mo of age, as well as the associated factors. MethodsIn a prospective cohort design, which we followed from a western Kenya postnatal clinic, 68 full-term HIV-uninfected infants born to HIV-1–infected mothers (HIV-exposed) and 65 full-term HIV-uninfected infants born to HIV-uninfected mothers were assessed at 6 wk and 6 mo of age. Breast milk intake of infants (51.9% female) weighing 3.0–6.7 kg (at 6 wk of age) was determined using the deuterium oxide dose-to-mother technique. Student t test for independent samples compared the variations in breast milk intake between the 2 groups. Correlation analysis detected the associations between breast milk intake and maternal and infant factors. ResultsDaily breast milk intakes by HIV-exposed and HIV-unexposed infants were not significantly different at either 6 wk (721 ± 111 g/d and 719 ± 121 g/d, respectively) or 6 mo (960 ± 121 g/d and 963 ± 107 g/d, respectively) of age. Maternal factors that significantly correlated with infant breast milk intake were FFM at both 6 wk (r = 0.23; P < 0.05) and 6 mo (r = 0.36; P < 0.01) of age and weight at 6 mo postpartum (r = 0.28; P < 0.01). Infant factors that significantly correlated at 6 wk were birth weight (r = 0.27; P < 0.01), present weight (r = 0.47; P < 0.01), length-for-age z-score (r = 0.33; P < 0.01), and weight-for-age (r = 0.42; P > 0.01). At 6 mo, they were infant length-for-age (r = 0.38; P < 0.01), weight-for-length (r = 0.41; P > 0.01), and weight-for-age (r = 0.60; P > 0.01). ConclusionsFull-term breastfeeding infants born to HIV-1–infected and HIV-1–uninfected women attending standard Kenyan postnatal care clinics ≤6 mo of age in this resource-poor setting consume comparable amounts of breast milk. This trial was registered at clinicaltrials.gov as PACTR201807163544658.