A recent study in Israel including data of 628,292 pregnant women did not show any association of adverse pregnancy events and air travel in pregnancy (1). The American College of Obstetricians and Gynecologists (ACOG) Committee Opinion No. 746 Summary published in August 2018 also stated that in the absence of obstetric or medical complications, occasional air travel is safe for pregnant women.
1. Specific risks of air travel
- Miscarriage and preterm birth
Concern has been raised by a meta-analysis of 9 studies which has shown a statistically higher chance of pregnancy loss (miscarriage or intrauterine fetal demise) among flight attendants than control (2). The risk of preterm birth < 37 weeks was also higher in passengers than control, but, interestingly, not among flight attendants. The criticism of this meta-analysis is that those 9 studies involved small sample size and were not of high methodological quality. While most authorities regard air travel is safe in general, those pregnancies with bleeding or high-risk of preterm birth should consider refraining from air travel for the benefit of doubt.
Pregnancy is associated with an increase in risk of thromboembolism (deep vein thrombosis or pulmonary embolism). Air travel may increase further the risk because of immobility, low oxygen tension and low humidity, which lead to venous stasis and dehydration. This is particularly the case for long-haul flights.
The Royal College of Obstetricians and Gynaecologists (RCOG) has the following recommendations:
- (i) Use aisle seat if possible to facilitate movement
- (ii) Mobilise throughout flight—every 30 minutes
- (iii) Increase water intake and avoid dehydration
- (iv) Consider elastic compression stockings for flights longer than four hours
- (v) Consider low molecular weight heparin in the presence of additional risk factors for deep vein thrombosis
- Irradiation exposure
There is no known risk to the fetus at a level of irradiation < 50 mSv. The radiation exposure of a 10 hours’ flight is estimated to be 0.05mSv only. Therefore, the risk of adverse irradiation effects to the fetus during a single flight is negligible.
2. Best timing of air travel
The second trimester (14-28 weeks) is regarded as the best timing for leisure travel
3. Safety of travel vaccines in pregnancy
Specific travel vaccines for certain areas can be found in the website of the Department of Health https://www.travelhealth.gov.hk. Inactivated vaccines or toxoids are in general considered safe but live attenuated vaccines (e.g. measles and typhoid) are not. Women need to consult their doctors before such vaccination.
1. Shalev Ram H, Ram S, Miller N, Rosental YS, Chodick G. Air travel during pregnancy and the risk of adverse pregnancy outcomes as gestational age and weight at birth: A retrospective study among 284,069 women in Israel between the years 2000 to 2016. PLoS One. 2020 Feb 6;15(2):e0228639.
2. Magann EF, Chauhan SP, Dahlke JD, McKelvey SS, Watson EM, Morrison JC.Air travel and pregnancy outcomes: a review of pregnancy regulations and outcomes for passengers, flight attendants, and aviators. Obstet Gynecol Surv. 2010 Jun;65(6):396-402.