Air travel is generally safe in uncomplicated pregnancies. There is no clear evidence that flying increases the risk of preterm labour, PROM, or abruption. Key physiological changes occur in-flight due to cabin altitudes of 4,000–8,000 feet. This results in a barometric pressure drop leading to a ~10% fall in maternal SpO2, which is typically well tolerated. Additionally, the low humidity environment (~15%) causes insensible fluid loss and mucosal dryness. Eustachian tube dysfunction and motion sickness may also occur.
Gestational Cut-Off Limits
Adhering to strict gestational cut-off limits is recommended to prevent in-flight labour.
- Singleton Pregnancy: Avoid travel from 37 weeks.
- Multiple Pregnancy: Avoid travel from 32 weeks.
VTE Risk & Prevention
Pregnancy is inherently a hypercoagulable state. For flights exceeding 4 hours, the VTE risk is roughly three times higher, increasing by ~18% for every additional 2 hours of flight duration.
- Non-Pharmacological Prophylaxis: All pregnant women on flights >4 hours should wear graduated elastic compression stockings (class II, 15–20 mmHg).
- Pharmacological Prophylaxis: Antenatal LMWH prophylaxis is indicated for high-risk women on the day of travel and potentially several days after. High-risk indicators include previous VTE, APS, thrombophilia, morbid obesity, nephrotic syndrome, or multiple risk factors.
- Aspirin is NOT recommended for VTE prophylaxis associated with air travel.
Contraindications to Flying
Patients must be screened for absolute medical contraindications before clearing them for air travel. These include:
- Severe anaemia (Hb < 7.5 g/dL).
- Recent haemorrhage.
- Sickling crisis.
- Serious cardiac or respiratory disease.
- Acute otitis media or sinusitis.
- Recent GI surgery.
- Recent fracture with cast and significant swelling risk.
Relative contraindications requiring careful consideration include threatened preterm labour, PPROM, severe pre-eclampsia, placenta praevia with bleeding, severe IUGR, and multiple pregnancy with complications.
Practical Counselling
To optimise safety and comfort in-flight, counsel patients on the following:
- Select an aisle seat for easier mobilisation.
- Walk regularly during the flight and perform calf exercises every 30 minutes.
- Maintain hydration, avoiding excess caffeine and alcohol.
- Fasten the seat belt low across the thighs/under the abdomen.
- Avoid prolonged immobility by changing positions frequently.
- Wear graduated compression stockings for flights >4 hours.
- Check airline policies and obtain a medical letter if >28 weeks or on LMWH.
- Ensure travel insurance includes pregnancy cover and access to maternity care at the destination.
Debunking Common Myths
- Myth: Flying causes miscarriage or preterm labour. Fact: There is no convincing evidence linking uncomplicated flights to these outcomes.
- Myth: Body scanners are harmful in pregnancy. Fact: The radiation dose is negligible and not clinically significant.
- Myth: Cosmic radiation from occasional flights is risky. Fact: The dose is very low and lacks clinical significance.
- Myth: Aspirin prevents VTE on flights. Fact: Aspirin is NOT recommended for this indication.
Conclusion
Air travel is highly safe for uncomplicated pregnancies when appropriate gestational limits are respected and evidence-based VTE prophylaxis measures are implemented. By systematically screening for absolute contraindications and providing thorough practical counselling on mobilisation and hydration, obstetricians can ensure patients remain safe and comfortable throughout their journey.
References
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Royal College of Obstetricians and Gynaecologists. Air travel and pregnancy: Scientific Impact Paper No. 1. London: RCOG; 2013.
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Magann EF, Chauhan SP, Bofill JA, Martin JN Jr. Air travel and pregnancy outcomes: a review of pregnancy regulations and outcomes for passengers, flight attendants, and aviators. Obstet Gynecol Surv. 2010;65(6):396-402. doi: 10.1097/OGX.0b013e3181e572ae.
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American College of Obstetricians and Gynecologists. ACOG Committee Opinion No. 443: Air travel during pregnancy. Obstet Gynecol. 2009;114(4):954-5. doi: 10.1097/AOG.0b013e3181bd1325.
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Hezelgrave NL, Whitty CJ, Shennan AH, Chappell LC. Advising on travel during pregnancy. BMJ. 2011;342:d2506. doi: 10.1136/bmj.d2506
