This study aimed to investigate the prevalence of maternal depressive symptoms at 5 and 9 months postpartum in a low-income and predominantly Hispanic sample, and evaluate the impact on infant weight gain, physical health, and sleep at 9 months. Participants included 132 low-income mother-infant pairs who participated in a larger investigation on prenatal care utilization. Mothers were interviewed in person 24-48 h after birth and by phone at 5 and 9 months postpartum. Clinically significant levels of depressive symptoms were reported in 33% of the women at 5 months postpartum, and 38% at 9 months postpartum. Higher depressive symptoms at 5 months were associated with less infant weight gain from 5 to 9 months, p = .002, increased infant physical health concerns, p = .05, and increased infant nighttime awakenings at 9 months, p = .001. Results suggest a striking prevalence of clinically significant depressive symptoms through 9 months postpartum in this very low income, largely ethnic minority sample. Further, the effects of postpartum depression include significant ramifications for infant physical health.