Pregnant Women Taking Lamictal for Bipolar Disorder

This study seeks to examine how the dose of lamotrigine (Lamictal) should be adjusted during pregnancy for women with Bipolar Disorder. The investigators predict that the concentration of Lamictal in women's blood will decrease during pregnancy, and increase after postpartum. Because the concentration of the medication is likely to decrease during pregnancy, it is important for doctors to know how much they should increase a patient's dose in order to prevent worsening of Bipolar symptoms. In this study, the investigators will ask that participants complete up to five overnight visits to our clinical research unit where their blood will be drawn every couple of hours, through an IV catheter, to measure how the concentration of lamotrigine (Lamictal) changes over time. Participants will be compensated for their time.