Many question whether it is safe for pregnant women to travel by air. When you’re talking about commercial airlines, and not rocket ships, parasailing, or bungee jumping, most doctors believe that it is safe for healthy pregnant women to travel by air under most circumstances. There are a few contraindications to flying when you are pregnant, and some airlines may not allow pregnant women to travel by air after their 36th week of pregnancy, unless they have a doctor’s note clearing them to fly.

It’s also the case that it may not be safe for pregnant women to travel by air frequently. While in flight, you are exposed to low levels of radiation. Consistent exposure, if you are a flight attendant or a pilot may make flying on too regular a basis unsafe, since radiation — even in low levels — can affect fetal development. Airlines frequently have rules to protect their employees from retaining their regular jobs if they are pregnant. This may not apply if you work at a job, not at an airline, where you must travel by air frequently. If your job or lifestyle requires frequent travel, you may need to discuss the potential impacts on your pregnancy and fetal health.

Most doctors suggest that it is safe for pregnant women to travel by air during the first two trimesters, but recommend not flying during the third trimester unless absolutely necessary. Cautions during the first trimester may have more to do with physical comfort than anything else. Provided a woman is healthy and the pregnancy is progressing normally, air travel is usually fine, but it may make early pregnancy symptoms like morning sickness and nasal congestion worse. There’s also some concern about the rate of catching viruses or infections on crowded planes, especially on long flights. Since some viruses can put you and your baby at risk, especially during the first three months, you might want to save traveling for the second trimester of your pregnancy.

It’s also possible to make it safer for pregnant women to travel by air, by observing a few precautions. Though rare, occasionally air travel will cause clotting of the blood in the legs, which can lead to emboli or stroke. To avoid this risk, use compression stockings, and get up every half hour to walk around, restoring good blood circulation to your legs. It’s also recommended that you drink plenty of water on long trips, since flying can dehydrate the body.

Sometimes it is not safe for pregnant women to travel by air, particularly if they have pre-existing medical conditions or a complicated pregnancy. If you have prenatal diabetes, uncontrolled hypertension, heart conditions of any kind, problems with your placenta, or any other conditions that make your pregnancy high risk, you should consult your doctor before you make your travel plans. Women who at risk for miscarriage or premature labor may also be told to avoid flying, and a women carrying a child with a severe medical condition may be asked not to fly in the third trimester to avoid the potential problems early labor might pose to the child.