Most U.S. airlines allow pregnant women to fly up to 36 weeks gestation on domestic flights. For international flights, 35 weeks gestation is usually the limit.

While travel in an airplane is almost always safe during pregnancy, the document does address some instances in which air travel should be avoided. Travel is not recommended at any time during pregnancy for women who have either medical or obstetric complications — such as pregnancy-induced hypertension, poorly controlled diabetes, or sickle cell disease — that could result in an unforeseen emergency. ACOG also advises against air travel by pregnant women at significant risk for premature labor or with placental abnormalities.

According to ACOG, environmental conditions associated with flying, such as low cabin humidity and changes in cabin pressure, may result in an increased heart rate, increased blood pressure and a significant decrease in breathing capabilities in pregnant women with a weakened cardiovascular system.