Women with bipolar disorder are particularly vulnerable to developing both postpartum psychosis and postpartum depression.Research has shown that childhood trauma may increase risk of postnatal depression in women without a history of mental illness and in women who have unipolar major depression. However, this relationship had not been investigated in women who have bipolar disorder. In almost 600 women with bipolar disorder we were able to conduct this important study to compare the rates of postpartum depression among women who did and did not experience childhood trauma. We found that childhood trauma was associated with more frequent episodes of depression across the lifetime but wasnot specifically associated with episodes of depression occurring following childbirth. To better understand this complex relationship, further research is needed to investigate other factors that may influence risk of postnatal depression in women who have bipolar disorder. This study was recently published the Journal of Affective Disorders.