Postnatal depression follows 10% of live births but there is little consensus on the risk factors associated with its development. Previous smaller studies have been unable to quantify the impact of independent risk factors as relative and attributable risks.

The Edinburgh Postnatal Depression Scale (EPDS) was used to screen a systematic sample of 2375 women, six to eight weeks after delivery. Information on socio-demographic and obstetric variables was collected at the screening interview. The risk factors associated with high EPDS scores (>12) were determined and entered stepwise into a regression model.

Four independent variables were found to be associated with an EPDS score above this threshold. These were an unplanned pregnancy (OR 1.44); not breast-feeding (OR 1.52), and unemployment in either the mother, i.e. no job to return to following maternity leave (OR 1.56), or the head of household (OR 1.50). These four variables appeared to explain the risk associated with other risk factors.

Although a direct aetiological role for these risk factors is not certain, they may indicate strategies for the prevention of affective morbidity in postnatal women. These may include reducing unwanted pregnancy and employment for women after childbirth.