Answer to Question #3368 Submitted to "Ask the Experts"

I am 3.5 weeks pregnant. I work in international marketing and do a lot of flying on commercial airliners for my job. I am scheduled to fly to Europe at the end of week six (nine hours flying time); from there to Hong Kong (13 hours) at the beginning of week eight, and back to the United States in week nine (19 hours). In week 10, I will fly domestically (three hours) and again in week 11 (nine hours). I am very concerned about the cumulative radiation exposure at the different stages of development in the first trimester but would prefer not to tell my employer about the pregnancy yet. I would greatly appreciate your expert opinion on whether the amount of radiation accumulated on these flights is likely to harm the baby.

I realize that you are flying more frequently than most passengers, but remember that pregnant stewardesses fly more frequently and studies of the pregnant stewardess population do not indicate that there are increased reproductive risks. The radiation exposures in flight are too low to contribute to the risk of miscarriage or birth defects. It is true that because you are 30,000 or 40,000 feet above the earth the exposure to passengers is higher. But not only is the exposure far below the threshold dose for producing reproductive effects, the radiation is protracted which further reduces its effectiveness. If you fly during solar flare activity, the fetal exposure will be higher, but it will still be below the threshold exposure for birth defects and miscarriage. If you are healthy with no reproductive problems or family history of reproductive problems your risk for birth defects is 3% and for miscarriage is 15% at the beginning of your pregnancy.

There is an excellent summary on the HPS website of the radiation exposure that occurs during flight by one of the other ATE HPS scientists. Please see Question 2783.

Robert Brent MD, PhD