Antenatal depression is associated with small-for-gestational age, but few studies have examined associations with weight during childhood. Similarly, few studies address whether antenatal and postpartum depression differentially affect child weight. Among 838 mother-child dyads in Project Viva, a prospective cohort study, we examined relationships of antenatal and postpartum depression with child weight and adiposity. We assessed maternal depression at mid-pregnancy and 6 months postpartum with the Edinburgh Postnatal Depression Scale (score > or =13 indicating probable depression). We assessed child outcomes at age 3 years: body mass index (BMI) z-score, weight-for-height z-score, sum of subscapular (SS) and triceps (TR) skinfold thickness (SS + TR) for overall adiposity, and SS : TR ratio for central adiposity. Sixty-nine (8.2%) women experienced antenatal depression and 59 (7.0%) postpartum depression. Mean (SD) outcomes at age 3 were: BMI z-score, 0.45 (1.01); SS + TR, 16.72 (4.03) mm; SS : TR, 0.64 (0.15). In multivariable models, antenatal depression was associated with lower child BMI z-score (-0.24 [95% confidence interval: -0.49, 0.00]), but higher SS : TR (0.05 [0.01, 0.09]). There was no evidence of a dose-response relationship between antenatal depression and these outcomes. Postpartum depression was associated with higher SS + TR (1.14 [0.11, 2.18]). In conclusion, whereas antenatal depression was associated with smaller size and central adiposity at age 3 years, postpartum depression was associated with higher overall adiposity.