Participation in this study will last up to 6 months postpartum. Study visits will be scheduled every 4 weeks during pregnancy and every 6 weeks after delivery for up to 6 months postpartum. During study visits, data will be collected on factors that may predict bipolar disorder recurrence and overall burden of bipolar disorder illness. Specific potential factors that will be evaluated include severity of illness in the past, type and severity of both recent and past life stressors, and any treatment received during pregnancy and the postpartum period. The study will also evaluate how antidepressant medications, if taken, affect the mother and baby during pregnancy and the postpartum period. Additionally, plasma, serum, and urine samples will also be processed and stored at each study visit.