Dear Ma am, Hi & Welcome. I can understand your concern for the safety of the prescribed medications for bipolar disorder. Yes, intake of these medications can affect the fetus (unborn baby) while pregnant. 1. Olanzapine is a FDA pregnancy category C drug. Taken during the third trimester of pregnancy the neonates are at risk of experiencing extra-pyramidal neurological disturbances and/or withdrawal symptoms following delivery. 2. Lithium is a FDA pregnancy category D drug. There s a strong evidence of harmful effect on the growing fetus if given during early pregnancy. There s a high risk of Ebstein s anomaly (a congenital malformation) that is characterized by abnormalities of the heart valve (tricuspid valve) and right ventricle if Lithium is taken during early pregnancy. If used during pregnancy, serum lithium levels should be closely monitored and prenatal diagnosis of malformations should be conducted. You should have periodic monitoring of your baby s heart using ultrasound scans. Use should be discontinued shortly before delivery & restarted a few days postpartum. After birth, the newborn should be monitored for signs/symptoms of lithium toxicity, including thyroid function. 3. Using Olanzapine together with Lithium may increase side effects such as drowsiness, confusion, and difficulty concentrating, impairment in thinking, judgment, and motor coordination which can result in falls and related injuries. You should avoid or limit the use of alcohol while being treated with these medications. This combination can also cause weakness, lethargy, fever, tremors, confusion, abnormal muscle movements, and increased white blood cells and other lab values has also been reported during combined use of these medications during the third trimester of pregnancy. Consult your treating psychiatrist for a safe but effective medications to treat bipolar disorder if you are planning for a pregnancy. Best wishes. A feedback is appreciated.