We recruited 93 pregnant women with a history of either major depression or bipolar disorder (I, II or not otherwise specified) and prospectively followed them during pregnancy and after delivery to identify genetic and clinical characteristics that precede the development of a postpartum depressive episode. Approximately one-third of the sample had bipolar disorder. The average age of the participants was 30.6 years and 70% of the sample was Caucasian. Participants were managed by their treating psychiatrist as clinically indicated and were evaluated during each trimester for pregnancy, and then 1 week, 1 month and 3 months postpartum. Women were classified as being depressed if they met the DSM-IV criteria for a major depressive episode based on a psychiatric interview at each time point (first, second and third trimester and 1 week and 1 month postpartum). We analyzed a subgroup of 32 women euthymic during the third trimester (prepartum euthymic), 34.4% of this subsample (N=11) became depressed within the first 4 weeks postpartum and met the DSM-IV criteria for major depressive episode. A second subgroup of 19 women depressed during pregnancy
