Background: Postnatal depression affects approximately 10% of women in the first postpartum year. This is the first study specifically designed to identify risk factors for postnatal depression in a population based sample of Australian women. ACT women were thought to be vulnerable to postnatal depression because of the social demographics of this population.

Aims: The aims of this paper are to provide information about the incidence of, and risk factors for, postnatal depression in the first 2 postpartum months in the ACT.

Methods: Data were collected in 1997 during a population based, prospective cohort study known as The ACT Experience : A Survey of Mothers. Women completed questionnaires on day 4 and at 8, 16 and 24 weeks postpartum. Data from the first 2 questionnaires will be considered in this paper. The primary outcome measure was the score on the Edinburgh Postnatal Depression Scale (EPDS). Women with scores > 12 were classified as cases.

Results: 1295 women agreed to participate and of these 1254 (96.8%) completed the second questionnaire. The incidence of positive scores on the EPDS at 8 weeks was 129/1254 (10.4%). After adjusting for confounding factors in a multivariate logistic regression model, the following factors remained significantly associated with scores >12 on the EPDS: age >40; previous psychiatric history; vulnerable personality; maternity blues; low social support; dissatisfaction with partner; poor relationship with mother and formula feeding.

Conclusions: The incidence of and risk factors for postnatal depression are consistent with overseas findings.