Forty-four per cent of the sample showed signs of postnatal distress in the 14 days following the birth. Breastfeeding duration was statistically significantly associated with psychological factors including dispositional optimism, breastfeeding self-efficacy, faith in breastmilk, breastfeeding expectations, anxiety, planned duration of breastfeeding and the time of the infant feeding decision. As a set, these psychological factors were more predictive of breastfeeding duration than was the set of socio-demographic characteristics. The duration of any breastfeeding was uniquely predicted by faith in breastmilk, planned breastfeeding duration and breastfeeding self-efficacy.