July 27, 2012

Many of my newly pregnant clients have concerns about flying during very early pregnancy.  The first trimester can feel very vulnerable and uncertain, particularly if you have a history of miscarriage or if it you have been trying to conceive for a long while. When I received an email recently asking about the risks, I decided to poke around a bit to see what I could find. This post is specifically about flying in early pregnancy; perhaps I’ll do future posts on the effects of travel on fertility and the risks of flying later in pregnancy, so stay tuned.

What are the theoretical risks of flying during pregnancy?

The main concern with air travel in early pregnancy is potential exposure to cosmic & solar radiation. Solar radiation is from the sun, cosmic radiation is from other stars.  Exposure increases on longer flights, flights at closer proximity to the poles, those at higher altitudes and those flying during a solar particle event (aka solar radiation storm).  We don’t have these exposures on the ground, because the atmosphere protects us.  Increase in radiation exposure may increase risk of fetal damage & mental retardation.

How much radiation is acceptable?

Different organizations offer slightly different numbers for acceptable exposure.  Here are a few relevant guidelines:

  • The International Commission on Radiological Protection (ICRP) recommends that work-related radiation exposure not exceed 20 mSv/year (or 2000 millirem); this would apply to flight attendants, X-ray technicians, etc.
  • The ICRP limit for the general public, however, is 5mSv/year (500 millirem)
  • The ICRP recommends that the fetus not be exposed to more than 1 mSv total (100 millirem)
  • The National Council on Radiation Protection & Measurements (NCRPM) recommends that the fetus not be exposed to more than 0.5 mSv (50 millirem) in any given month

I know. Those number don’t mean a thing to you, right? Here’s some context.  Under normal conditions, you would get between 0.02 and 0.05 mSv (2-5 millirem) of radiation in a typical cross-country flight – just under ½ of what you’d get in a chest x-ray.  It would take 7 round trips from Athens to New York to achieve the 1 mSev exposure limit recommended by the ICRP during pregnancy. According to the EPA, the average person in the US will be exposed to 360 millirem of radiation each year, including exposure from commercial flights as well as other sources, both manmade and natural.

What’s the deal with solar storms?

Solar storms, sun spots, and so forth can significantly raise radiation levels once you get above the atmospheric protection. The “normal conditions” noted above do NOT include periods of high solar activity. According to the EPA, The FAA keeps track of solar events and alters flight plans (reducing altitude) if a flight is traveling during one.  That being said, the Association of Flight Attendants recommends watching solar radiation levels and not traveling by air during times of high solar radiation. More info below on how you can tell when those are happening.

What do the studies show?

The data is very vague on this. A recent review article analyzed risks of air travel with regard to pregnancy outcomes, and found a greater risk of spontaneous abortion (miscarriage) in flight attendants (and not in passengers), but also noted that this topic has been “poorly studied in a limited number of investigations” and that the research was generally not “of high methodologic quality.” There is no way to tell whether this potential increase in risk is due to radiation exposure or other factors.

The American College of Obstetrics & Gynecology (ACOG)’s official statement is characteristically vague and pacifying: “For most air travelers, the risks to the fetus from exposure to cosmic radiation are negligible. For pregnant aircrew members and other frequent flyers, this exposure may be higher. Information is available from the FAA to estimate this exposure.”

Is there a way to track radiation exposure or solar activity?

The FAA offers a calculator that will tell you how much radiation you were exposed to on any given flight if you know the approximate dates of travel (month & year) and cruising altitude of your flight. The CARI-6 can be downloaded for free here.

Here is some information from the Association of Flight Attendants on how to identify solar particle events “Check this website before going to the airport. If the green line is above “10 to the zero” on the left side of the graph, it is recommended that pregnant women postpone travel. To help you interpret the graph that you see on your computer screen, here is an example of a graph with no Solar Particle Event (SPE) and here is one with a SPE of health significance. The NOAA Space Weather Prediction Center will also notify you of these solar events for free by email. This is especially important information if you are pregnant.” (See the AFA website for other information about cosmic/solar exposure & reproductive health and specifically how to sign up for NOAA notifications).

What’s the take home message?

You & your growing baby are most likely fine if you will be taking a small number of short flights during early pregnancy, especially if the flights involve more Southern latitudes.  I would personally advise against numerous long-distance/international flights during pregnancy, especially those scheduled to fly in the more Northern latitudes, and flights during periods of increased solar activity.

If you do need to fly frequently or if you are getting overly anxious about the exposure, I’d suggest the following visualization before boarding the plane.  Imagine a shield or protective covering encircling your uterus and the growing child inside. Some people visualize a heavy cloak, others a barrier of light or thick radiation-proof armor – use whatever works for you. Use this visualization to protect your uterus from any dangers while you are flying and release it once the trip ends. Safe travels!

Flying during Pregnancy Resources:

About Camille Freeman, LDN, RH (she/her)

Hi there! I'm a clinical herbalist and licensed nutritionist specializing in fertility and menstrual health. I run the Monday Mentoring community of practice and also offer continuing education programs for highly-trained herbalists and nutritionists (Check out this year's Deep Dive!). I'm also a professor in the Department of Nutrition at the Maryland University of Integrative Health, where I teach physiology, pathophysiology, and mindful eating.

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