Is air travel safe during pregnancy?
For all practical purposes, the answer to this question is yes. However, some concerns have been raised regarding exposure to cosmic radiation, as well as dehydration and blood clots that may occur during a flight. Regarding exposure to cosmic radiation, available studies are limited and primarily focus on flight attendants and individuals who frequently fly. There is no official evidence showing that occasional air travel increases the risk of health problems for a fetus.
Because pregnancy increases the likelihood of blood clot formation, prolonged immobility during long flights can lead to venous thrombosis in the legs. This can be exacerbated by the low humidity in the cabin, which leads to dehydration and, in turn, increases blood viscosity and the likelihood of clot formation. However, if you keep yourself hydrated by drinking water regularly and avoiding alcohol, and if you get up from your seat every 1–2 hours, no problems should arise.
It is also important to note that any pregnancy, including those classified as low-risk, can unexpectedly develop into a high-risk pregnancy. If this occurs during a flight, it could potentially pose a threat to the fetus. However, this can happen anywhere, and air travel does not increase the likelihood of such an event.
Up to which week you can fly
In an uncomplicated pregnancy, air travel is considered safe up to 36 weeks for a singleton pregnancy and up to 32 weeks for twins. Most airlines require a medical certificate from week 28 onward, stating your estimated due date and that the pregnancy is progressing normally. Rules differ from airline to airline, so check them before booking your ticket and take your return date into account as well.
The best time to travel
The second trimester, from week 14 to week 28. Nausea has eased, energy has returned and the risk of miscarriage or preterm birth is at its lowest. See what changes at each phase in our guide to pregnancy stages week by week.
When flying is not recommended
- vaginal bleeding or threatened preterm labor,
- placenta previa after the second trimester,
- preeclampsia or uncontrolled hypertension,
- severe anemia,
- recent thrombosis or a serious heart or lung condition.
In these cases, consult your obstetrician before any trip.
Practical tips for the flight
- Choose an aisle seat and get up for a short walk every half hour to hour.
- Do ankle exercises while seated.
- On flights longer than four hours, wear graduated compression stockings. If you have additional risk factors for thrombosis, your doctor may recommend preventive treatment.
- Drink water regularly and avoid carbonated drinks and foods that cause bloating.
- Fasten the seat belt low, below your belly, across your hips.
- Keep your pregnancy record, your test results and your medications in your carry-on.
Before traveling abroad
Check whether your travel insurance covers pregnancy and preterm birth, and find out where the nearest maternity hospital is at your destination. Avoid areas with malaria or Zika virus and destinations that require live virus vaccines. Be careful with water and raw foods, just as in Greece: remember which foods to avoid during pregnancy.
What happens to your body in the cabin
The airplane cabin does not maintain sea-level pressure. During the flight it corresponds to an altitude of about 1,800 to 2,400 meters, as if you were on a high mountain. The oxygen in your blood drops slightly. For a healthy pregnant woman and a normally growing fetus this does not matter, because fetal hemoglobin binds oxygen very efficiently.
Other changes are more noticeable:
- Very low humidity: the cabin air is dry, so you lose fluids without realizing it. Dehydration increases fatigue, headaches and the risk of thrombosis.
- Gas expansion: intestinal gas expands as pressure drops, which is why bloating is common.
- Ear pressure: the nasal congestion of pregnancy makes it harder to equalize pressure, especially during descent.
If you have severe anemia, heart disease or lung disease, this small drop in oxygen matters more. In that case, the decision to fly is made together with your doctor.
Blood clots on flights: which pregnant women need extra protection
Pregnancy itself increases the risk of thrombosis in the leg veins several times over, because the blood clots more easily and the uterus presses on the pelvic veins. Sitting still in your seat for hours adds one more factor. For most women, moving around, fluids and graduated compression stockings are enough.
However, some pregnant women need an individual assessment before a flight longer than four hours:
- those who have had thrombosis in the past or have a known thrombophilia,
- women with a body mass index above 30,
- multiple pregnancy,
- smokers,
- pregnancy after in vitro fertilization, especially in the first trimester,
- significant varicose veins or a recent hospital stay.
In these cases, your doctor may recommend preventive treatment for the flight. Do not take aspirin or any other “blood thinning” medication on your own before flying: the choice is made only after consulting your doctor.
A practical flying guide for each trimester
First trimester
Nausea and fatigue are the biggest enemies of travel. Choose morning flights if your nausea gets worse in the afternoon, and bring dry crackers. Before a long trip, it is best to have had your first ultrasound, to confirm that the pregnancy is inside the uterus. An ectopic pregnancy that has not been diagnosed can cause pain and bleeding, and you do not want that to happen on a flight or in a country with limited access to a hospital.
Second trimester
The most comfortable time. Plan your trip around the key tests: the anatomy scan at around 20 to 23 weeks and the glucose tolerance test at 24 to 28 weeks for gestational diabetes. That way you will not need to reschedule them.
Third trimester
Your belly makes the seat feel tight, and you need the restroom often. Book an aisle seat and, if possible, one in the front rows. Calculate your gestational age on the day of return, not departure, and tell your doctor your dates so they can adjust your appointments.
The fit-to-fly letter: what it says and when to get it
The letter airlines ask for is simple, but it must contain the right information. It usually includes:
- your estimated due date,
- whether it is a singleton or multiple pregnancy,
- that the pregnancy is progressing normally and without complications,
- that there is no contraindication to air travel,
- the date of issue and the doctor's details.
Many airlines only accept a letter issued a few days before the flight. So schedule an appointment close to your departure and ask for the letter in English if you are traveling abroad. Keep a copy for the return flight as well.
What to pack in your carry-on
- Your pregnancy record, blood type and your most recent tests and ultrasounds.
- The medical certificate, if you need one.
- Your medications and vitamins in their original packaging, with enough for a few extra days.
- Compression stockings, put on before boarding.
- An empty water bottle to fill after security.
- Small, light snacks: crackers, nuts, fruit.
- A small lumbar pillow.
- Your travel insurance details and your obstetrician's phone number.
Nausea, bloating and swelling: in-flight discomforts
Most in-flight discomforts are not dangerous, but they can spoil the trip. A little preparation goes a long way.
- Motion sickness: seats over the wings move less. Look into the distance, not at a screen, and eat something light before the flight. Take anti-nausea medication only after consulting your doctor.
- Bloating: avoid legumes, cabbage and soft drinks on the day of travel.
- Ears: chew, swallow often or drink water during takeoff and descent. Use nasal decongestants only if your doctor approves them.
- Swollen feet: wear comfortable, roomy shoes, because your feet swell on long flights and it can be hard to put your shoes back on.
Car, ferry or plane? Travel options within Greece
For short distances, a car gives you flexibility, but the same rules apply: stops every one to two hours, the seat belt low under your belly and diagonally between your breasts, and never a disabled airbag without a reason. A ferry is comfortable in good weather, but rough seas make nausea worse.
In the third trimester, the most important question is not the means of travel but the destination. Small islands do not always have a maternity unit or a neonatal unit, and medical transfer depends on the weather. After 34 to 35 weeks, discuss with your doctor whether your destination gives you quick access to obstetric care.
After the flight: signs that need medical attention
Seek help right away if, in the following days, you develop:
- pain, swelling or warmth in one calf,
- shortness of breath, chest pain or coughing up blood,
- vaginal bleeding or fluid leakage,
- regular, painful contractions before 37 weeks,
- noticeably reduced baby movements,
- fever after traveling to a tropical country.
The first two may signal thrombosis or a pulmonary embolism and are treated as emergencies.
Radiation and frequent flying for work
Cosmic radiation at the altitude where airplanes fly is higher than on the ground, but the dose from a single flight is small. A long transatlantic flight gives a dose on the order of a simple chest X-ray. For a pregnant woman who flies a few times a year, this has no practical significance.
The issue mainly concerns those who fly very often: crew members, pilots and women who travel for work almost every week on long, polar routes. European legislation sets a dose limit for the fetus of pregnant workers, and many airlines remove pregnant flight attendants from flight duty as soon as they announce the pregnancy. If your job involves a lot of flying, discuss with your doctor and your occupational health physician how many flight hours are reasonable for the rest of your pregnancy.
Food, water and gestational diabetes while traveling
Hours at the airport and time zone changes disrupt your meal schedule. A little planning keeps your blood sugar and energy steady.
- Drink a glass of water about every hour of flight, and limit coffee and soft drinks.
- Choose sandwiches with well-cooked meat or cheese made from pasteurized milk. Avoid salads of unknown origin, sushi and cold cuts that have not been heated.
- If you have gestational diabetes, keep your glucose meter, test strips and snacks for low blood sugar in your carry-on. Insulin must always travel in the cabin, not in checked baggage, together with a medical certificate.
- When traveling across several time zones, ask your doctor how to adjust your meals and your treatment.
Frequently Asked Questions
Can I fly in the first trimester?
Yes. Flying does not increase the risk of miscarriage. Nausea and fatigue, however, can make the trip harder.
Are airport body scanners safe?
Yes. Metal detectors and millimeter-wave scanners do not use ionizing radiation and are considered safe during pregnancy.
Can flying cause preterm labor?
No. The pressure change in the cabin does not cause labor or rupture of the membranes. The restriction in the last weeks exists because labor can start at any time.
Do I need a doctor's note to fly?
Usually from week 28 onward. Ask the airline exactly what it requires and how recent the letter must be.
How many hours of flying are allowed?
There is no limit on hours. On flights longer than four hours the risk of thrombosis increases, so you need to move often, stay hydrated and wear compression stockings.
Can I fly after embryo transfer?
Yes. Flying does not affect embryo implantation, so you can fly home after the embryo transfer. However, because a pregnancy after IVF carries a slightly higher risk of thrombosis, follow the prevention measures on long flights and let your doctor know.
Can I take medication for nausea before the flight?
There are anti-nausea medications used in pregnancy, but take them only after consulting your doctor. First try a seat over the wings, a light meal before the flight and ginger.
What do I do if contractions start during the flight?
Tell the cabin crew right away. Crews are trained in first aid and can look for a doctor among the passengers or contact medical support on the ground. Drink water, lie on your side if possible and note how often the contractions come.
Can I fly if I had bleeding earlier in pregnancy?
It depends on the cause and on whether the bleeding has stopped. Light bleeding in the first trimester that has been checked and has not recurred is usually not an obstacle. Always get your obstetrician's approval before booking tickets.
