A group of first-time mothers (119) were interviewed repeatedly at fixed intervals during their pregnancies and until their babies were a year old; they were then followed up at four years. A similar investigation was carried out on 38 other primiparae and 39 multiparae, but only postnatally. The incidence of depressive neurosis rose significantly in early pregnancy and in the first three months after delivery (10 per cent and 14 per cent of the main sample respectively). Subjects mainly suffered either from antenatal or postnatal depression, not both. Marital conflict and severe doubts about having the baby were associated with depression at either time. Bereavement and preterm birth were the only life events to relate with the onset of depression and bereavement had a greater impact during pregnancy. Depressed mothers were more likely to express negative or mixed feelings about their three-month-old babies. Many who had become depressed for the first time in their lives continued to experience psychological problems for up to four years after childbirth.