As part of a prospective investigation of postnatal psychiatric disorder, 66 women, randomly selected antenatally, completed visual analogue scales postpartum and rated their mood state daily for two weeks following childbirth. They were then interviewed using the Goldberg Standardised Psychiatric Interview on four occasions up to 14 months postpartum. Dysphoric mood was temporally related to childbirth. Emotional lability was the important affective component of the puerperium. A significant correlation was found between the blues and subsequent postnatal depression. Lability of mood in the puerperium was related to psychiatric symptoms up to 14 months postpartum and was the strongest predictor of later psychopathology. Maternity blues ratings were not accounted for by labour variables.