This is the conclusion reached by the authors of a review published recently in the journal The Lancet Psychiatry. Pregnancy depression most commonly affects women in the last trimester of pregnancy and immediately after the birth of the baby. The statistics are alarming - 1 in 5 women suffer from the disorder, and with them entire families. It is characterised by a lowered mood, a feeling of helplessness and a lack of motivation to be a mum. Pregnancy depression can be caused by external (e.g. bereavement) and internal (disturbances in the concentrations of relevant neurotransmitters) factors.