Perinatal depression has a number of adverse outcomes for the whole family. Depression in pregnancy is associated with an increased risk for pre-eclampsia, preterm delivery, and fetal growth retardation. The majority of cases of depression identified in the obstetric setting are unipolar depression, but screening is done for bipolar depression to identify women at risk for or who have developed post-partum psychosis. For women with milder symptoms who prefer psychosocial treatment, it should be considered first-line. Psychotropic medications do cross the placenta and are present in amniotic fluid. Current research indicates that serum levels of antidepressant drugs in infants of breastfeeding mothers are typically undetectable or very low. Treatment with omega-3 fatty acids and light therapy may be beneficial for depression during pregnancy. Both carbamazepine and valproate are considered human teratogens and should be avoided in pregnancy when possible.