Abstract
Twenty-one cunsultant psychiatrists participated in a prospective study of post-abortion psychosis among a population of 1 333 000 people. During the 15-month study only a single case was reported, concerning a woman who had a history of two previous attacks of puerperal psychosis. The incidence of post-abortion psychosis was 0-3 per 1000 legal abortions. The incidence of puerperal psychosis, which was also studied as an index of validity, was 1-7 per 1000 deliveries. This conforms with currently accepted figures and indicates that the study population was representative. I suggest that physiological changes, which are probably more profound after childbirth than after abortion, may be responsible for the higher incidence of puerperal psychosis.