Is flying by trimester safe during pregnancy?

What does the evidence say about flying by trimester during pregnancy?

1. Occasional air travel is safe for most pregnancies that don't have medical complications, though the most common pregnancy emergencies tend to happen in the first and third trimesters. 1
2. Most U.S. airlines allow domestic travel until about 36 weeks, but it's worth checking your specific airline's policy before you book. 2
3. Flights longer than 4 hours carry a small increase in blood-clot risk, so getting up to walk, drinking water, and wearing compression stockings can help. 3
4. The cosmic radiation you're exposed to on a normal commercial flight isn't considered a hazard for occasional flying. 1

Is flying by trimester safe in each trimester?

• First trimester. Miscarriage and ectopic pregnancy are more common early on, and they're harder to manage far from your own care team. Otherwise, a routine short flight is generally considered fine.
• Second trimester. This is often the most comfortable time to travel: nausea is usually easing, energy is coming back, and moving around is still easy. Many people plan longer trips during this window.
• Third trimester. U.S. domestic airlines typically allow flying until about 36 weeks. International airlines vary and may ask for a letter from your provider, and after 36 weeks, most people hold off on travel since labor could start at any time.