Unless a pregnant woman has specific medical problems or problems with her pregnancy, the American College of Obstetricians and Gynecologists, the biggest group of ob-gyn doctors in the United States, states that pregnant women can fly safely up to thirty-six weeks of gestation. The climate of the airplane, including elements like the low humidity in the cabin and changes in the pressure in the cabin, do temporarily change the mother’s heart rate, blood pressure, and breathing, but they have not been proven to have any detrimental effects on the baby. There are some unconfirmed reports that flight attendants have an increased chance of miscarrying or having a spontaneous abortion compared to nonemployed women, but not compared to other employed women. However, there is no scientific evidence of an increased risk of miscarriage among other pregnant women who fly.
One study followed 222 women, of whom 118 traveled by air at least once during their pregnancy. When the physicians compared the two groups, there were no differences in length of pregnancy, the risk of having a premature baby, the babies’ birth weights, the risk of vaginal bleeding, how often the babies were admitted to the neonatal intensive care unit, or in any combination of all the possible things that could go wrong during pregnancy.
A major concern with lengthy air travel is deep vein thrombosis (DVTs) or clots in the veins of the legs that can then travel to the lungs. Experts suggest that pregnant women may be at increased risk for having DVTs, but there are no published reports of an actual increase in DVTs in pregnant women because of air travel. Nonetheless, all air travelers should take precautions to avoid DVTs by frequently flexing the ankles and feet and taking regular walks in the aircraft.
Some pregnant women also fear exposure to noise vibration or to cosmic radiation in the atmosphere while traveling by airplane. There is not a lot of scientific evidence that has tested whether these are problems for an unborn baby. The existing studies of the health effects of aircraft noise and of galactic cosmic radiation exposure for anyone during air travel indicate that any potential risk to a pregnant woman is so small that it should not be cause for alarm.