This study aims to investigate hospital admission of major depressive disorders (MDD) before and after birth. Population data for all primiparous women admitted to the hospital with depressive disorders before and after birth were used. The comparison group consisted of 10 % of primiparous women not admitted to the hospital with a diagnosis of a psychiatric disorder or substance use. A total of 728 women had a first admission with depressive disorders (501 in the first postpartum year). The rate of first hospital admission for depressive disorders decreased during pregnancy and increased markedly in the first three months after birth (peaking in the second month with a rate of 10.74/1,000 person year and rate ratio of 12.56) compared with the 6 months prior to pregnancy. Admission remained elevated in the second postpartum year. Older maternal age, smoking, elective caesarian section and admission to a neonatal intensive care unit or special care nursery were associated with a higher rate of admission. Women born outside Australia and those most socioeco-nomically disadvantaged were less likely to be admitted to the hospital in the first postpartum year. Overall risk of hospital admission with depressive disorders rose significantly across the entire first postpartum year. This has significant implications for policy and service planning for women with mood disorders in the perinatal period.