BackgroundIn Australia, there is limited evidence on the impact of antenatal depression on perinatal outcomes. This study investigates the association between maternal depressive symptoms during pregnancy and key perinatal outcomes, including birth weight, gestational age at birth, breastfeeding indicators and postnatal depressive symptoms.MethodA retrospective cohort of mothers (N = 17,564) of all infants born in public health facilities within South Western Sydney Local Health District and Sydney Local Health District in 2014, in the state of New South Wales (NSW), Australia, was enumerated from routinely collected antenatal data to investigate the risk of adverse perinatal outcomes associated with maternal depressive symptoms during pregnancy. Antenatal depressive symptoms were measured using the Edinburgh Postnatal Depression Scale (EPDS). Logistic regression models that adjusted for confounders were conducted to determine associations between antenatal depressive symptoms and low birth weight, early gestational age at birth (<37 weeks), breast feeding indicators and postnatal depressive symptoms.ResultsThe prevalence of maternal depressive symptoms during pregnancy was 7.0% in the cohort, and was significantly associated with postnatal depressive symptoms [Adjusted Odd Ratios (AOR) = 6.4, 95% CI: 4.8–8.7, P<0.001]. Antenatal depressive symptoms was associated with a higher odds of low birth weight [AOR = 1.7, 95% CI: 1.2–2.3, P = 0.003] and a gestational age at birth of <37 weeks [AOR = 1.3, 95% CI: 1.1–1.7, P = 0.018] compared to women who reported lower EPDS scores in antenatal period. Antenatal depressive symptoms were not strongly associated with non-exclusive breast feeding in the early postnatal period.ConclusionMaternal depressive symptoms in the antenatal period are strongly associated with postnatal depressive symptoms and adverse perinatal outcomes in Australian infants. Early identification of antenatal and postnatal depressive symptoms, and referral for appropriate management could benefit not only the mother’s mental health, but also the infant’s health and development.