Project Summary/Abstract Antipsychotics are a class of commonly used medications that are used for multiple indications within psychiatry, including psychosis, mood stabilization, and augmentation for depression. The use of antipsychotics among pregnant and lactating women has increased in frequency in recent years. However, their efficacy has not been directly tested in this population, and many unanswered questions remain about the potential effects of antipsychotics on the development of the fetus, neonate, and infant. We propose to conduct a prospective observational study of maternal psychiatric course and infant development among women with severe mental illness, comparing women treated with antipsychotics to women treated with other medications or without medication. The primary study outcomes will be psychiatric relapse in the mother, EEG abnormalities in the infant at 6 months, and behavioral and psychosocial outcomes at 18 months. We hope to determine whether antipsychotics are effective for pregnant women with severe mental illness and whether they have any measurable effects on infant development. This information will help women with severe mental illness make informed decisions about their care in pregnancy.