Why do women experience mood disorders following childbirth?

Mood disorders are common in pregnancy and the postpartum period and there is little doubt of the clinical and public health importance of affective illness occurring at this time. However, over recent years the scientific concept of postnatal depression has been challenged by studies suggesting no increased risk of depression at this time and little difference in the clinical presentation, response to treatment or prognosis of depression presenting in the postpartum and non-postpartum period. In the case of bipolar disorder (manic depression), however, there is compelling evidence that the postpartum is a period of very high risk and evidence is emerging to suggest that, for at least a proportion of women with major depression, there is a specific relationship to a childbirth related trigger. The author will consider some of the lines of evidence pointing to a specific relationship between childbirth and mood disorders and argue that this link is an important clue that can inform understanding, not only of postpartum mood disorders, but of affective disorders in general.