Hi, There is definite teratogenic effect detected by use of budesonide and formoterol in studies in chicken. However, results are not in consensus, rather different studies have conflicting reports with use of budesonide and formoterol in human being. Still, the dosage used during inhalation, are usually small and also duration and doses may be adjusted to the minimum effective dose to minimize / abolish their teratogenic effect. Hence, till a consensus is reached about safety of this for use during pregnancy, it should be advised, that this may be used with careful monitoring taking into consideration of benefits vs risks of its use during pregnancy. As, in untreated / undertreated asthma in asthmatic mothers during pregnancy, itself may cause fetal hypoxia leading to congenital malformations in fetus as well as preterm delivery and fetal death. Take care. Hope I have answered your question. Let me know if I can assist you further. Regards, Dr. Satnarain Bansal, General & Family Physician