BACKGROUND It is unclear whether the causative factors of non-psychotic postnatal depression are the same as those of depression at other times.
METHOD The course and recurrence of postnatal depression was studied in two groups of primiparous women experiencing an index episode of postnatal depression: those for whom the mood disorder had arisen de novo (n = 34), and those for whom it was a recurrence of previous affective disturbance (n = 21). The mental state of these two groups, together with a psychiatrically well control group (n = 40), was studied for five years.
RESULTS It was found that those for whom the index episode was a recurrence of depression were at raised risk of further non-postpartum episodes but not postpartum episodes, and that those for whom the index episode had arisen de novo were at raised risk for further episodes of postnatal depression but not for non-postpartum episodes.
CONCLUSION These findings suggest a specific nosologic reference for the concept of postnatal depression.