Air travel is a convenient and common form of transport and is used by approximately two billion passengers worldwide each year. Many women have jobs that involve frequent air travel and healthcare professionals are often asked questions regarding the safety of flying in pregnancy. However, there is no evidence that, if you have an otherwise uncomplicated pregnancy, air travel will increase the risk of pregnancy complications.
If you have medical or pregnancy-related conditions that could be worsened by flying, or could need urgent obstetric care during the flight, you should avoid travelling by air. Check with your midwife or obstetrician if unsure. Each decision should be based on the individual pregnancy and circumstances of travel, including the length of flight and destination. It is also advisable to inform and check with the individual airline carrier on every occasion when you are considering flying.
If your pregnancy is going well and is uncomplicated, most commercial airlines will allow you to fly up to 37 weeks of gestation for singleton pregnancies and up to 33 weeks for uncomplicated twin pregnancies. After 28 weeks’ gestation, you should carry a letter from your GP or obstetrician confirming that your pregnancy is uncomplicated and specifying the estimated date of delivery, otherwise you may be refused travel at the airport. It may also be more difficult to get travel insurance after 37 weeks’ gestation.
If you are at increased risk of a miscarriage of ectopic pregnancy, the location and viability of pregnancy should be confirmed by a hospital ultrasound scan before you travel. This would apply if you have had previous miscarriages or an ectopic pregnancy, previous tubal surgery, previous pelvic inflammatory disease or have become pregnant after sterilisation or whilst using an intrauterine contraceptive device (coil). If you experience any vaginal bleeding or abdominal pain, it is advised that you defer your travel until the symptoms have settled and an ultrasound scan has confirmed the location and viability of the pregnancy.
The best time to travel by air is thought to be the second trimester of pregnancy. Most women find that nausea has subsided by now and energy levels are higher. The complications of pregnancy, including miscarriage, are also much less likely. Some women may be at increased risk of pre-term labour (i.e. delivery before 37 weeks) or have medical conditions that are worsened by air travel, in which case travel plans should be reconsidered.
When planning a holiday, you should take into account the availability of hospitals at your travel destination. Proximity to a hospital as well as facilities for managing premature infants is very important. Serious adverse pregnancy events, such as major bleeding in pregnancy and cord prolapse (when the umbilical cord comes out of the uterus before the baby is born) may be life threatening and difficult to predict. Ensure you have insurance that specifically covers pregnancy-related care as any emergency care costs can be significant. It’s worth noting that although cabin crew are trained to deliver babies, they will not be able to manage any emergencies in the air.
The following list is a useful starting point for considering your pregnancy travel luggage needs:
Most pregnant women have no problems when flying, however, you may experience some discomfort, including swelling of your legs due to fluid retention. You may also have nasal congestion as during pregnancy you are more likely to have a blocked nose. Combined with this, the changes in air pressure in the aeroplane can cause you to experience problems in your ears.
You should wear your seatbelt continuously while seated as turbulence may be difficult to predict. The seatbelt should be belted low on the hipbones between the lower part of your abdomen and top of the thighs, not across your bump. The cabin crew will help you if you need a seatbelt extension.
A deep vein thrombosis is a blood clot which can form in your leg or pelvic veins. It causes pain and swelling in the leg and can travel up to the lungs (pulmonary embolism) and be life-threatening. When you are pregnant (and for the six weeks after the baby’s birth), you have a 10-fold higher risk of developing a clot compared to non-pregnant women. You are at increased risk of developing a clot if you fly whilst being pregnant. This is especially the case in long-haul flights of greater than four hours’ duration, when immobility, low humidity and dehydration play important roles.
It is recommended that you wear properly-fitted graduated elastic compression stockings during flights lasting more than four hours. If you have additional risk factors for blood clots such as being overweight, are a smoker, are over 35 years of age, or have a condition which predisposes you to clot more readily (a thrombophilia), you may need to take blood thinning injections of low molecular weight heparin for the day of travel as well as for a number of days after the flight. This should be a decision made by your obstetrician, who will decide the duration of the injections based on an individual risk assessment following a full discussion of the risks and benefits.
General measures to avoid a clot include:
The increased cosmic (high energy) radiation associated with occasional air travel in pregnancy is not considered significant in terms of risk to the mother or baby. There is no known increase in miscarriage, fetal malformations or effects on growth at levels of radiation less than 50 millisieverts (mSv). The exposure from a 10-hour flight is estimated to be only 0.05 mSv. Just living in the UK gives an estimated cumulative background radiation per year of 2.2 mSv. The risk to the baby of a single period of air travel is, therefore, negligible; however, if you are a frequent flier, caution should be used.
Similarly, the total radiation from a body scanner used for security purposes in airports is less than that received from two minutes of flight, or from one hour at ground level. Negligible radiation doses are absorbed into the body so that the dose reaching the fetus is much lower than the dose to a pregnant woman. There is no data to suggest that you should avoid such security checks.
The World Health Organisation (WHO) advises pregnant women not to travel to altitudes over 3000m, because of the risk of hypobaric hypoxia, a condition where the body is deprived of a sufficient supply of oxygen from the air to supply the body’s tissues. Travel to areas with altitudes up to 2500m is considered safe, however.
In the air, your heart rate and blood pressure may go up in order to adapt to the relatively lower oxygen content of airplane cabins. The baby is still able to maintain higher oxygen saturations in this environment as fetal haemoglobin (the oxygen carrying part of red blood cells) has a greater affinity for oxygen than adult haemoglobin. Pregnant women with serious pre-existing heart or lung disease, a recent sickle cell crisis, recent bleeding or with severe anaemia (a haemoglobin reading of less than 80 g/L), are strongly advised against air travel as they may not be able to tolerate the low oxygen environment. Additional oxygen should be considered if travel is absolutely necessary in these circumstances. Women with known mild to moderate anaemia (haemoglobin between 80 and 105 g/L) should aim to optimise their haemoglobin before they travel. There are other conditions where air travel may be strongly discouraged and each woman should be risk stratified and advice should be individualized.
Antimalarial prophylaxis should be used if you are planning to travel to endemic areas and up-to-date advice regarding immunisations prior to travel must be sought. Vaccines which contain inactivated viruses, bacteria or toxoids are considered safe, however, live vaccines, such as yellow fever, should be avoided. During the recent Zika epidemic, it was advised that pregnant women should postpone non-essential travel to areas with active Zika transmission until after pregnancy. Women should also avoid becoming pregnant while travelling in an area with active Zika virus transmission, and for 8 weeks following returning home (whether they had symptoms of Zika infection or not).
In summary, there is no evidence that air travel in pregnancy increases the risk of pregnancy complications, however, it is important to be individually risk assessed each time you travel. There is a small increase in the risk of venous thromboembolism if your flight is more than four hours’ duration, but the absolute risk is still low.