However much she has longed for a baby, however supportive her husband and family, however uncomplicated her labour, a new mother may find herself inexplicably tearful and depressed. Sometimes called ' The Baby Blues', it doesn't usually last for long. But for one in every ten mothers it becomes a serious problem - so serious that she needs help. And for some women (one in every 200), childbirth triggers off a severe illness called puerperal psychosis. Jeanne la Chard and Nick Ross ask doctors and psychologists about the causes of post-natal depression and how it can be treated. Also in the programme are those who've had first-hand experience of post-natal depression.