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11 October 2008

Answer to Question #2011 Submitted to "Ask the Experts"

Category: Pregnancy and Radiation — Exposures not directly to embryo/fetus

The following question was answered by an expert in the appropriate field:

I have just found out that I'm pregnant, but the problem is I had a thyroid scan done with radioactivity liquid while I was already pregnant, which I didn't know about. I might have been in the second week of pregnancy. How does it and how can it affect my pregnancy?

If you had a diagnostic thyroid scan with radioactive ¹³¹I, then the exposure to your embryo will be very low and not change your reproductive risks. Furthermore, the fetus's thyroid does not develop until after the eighth week and by that time there will practically be no radioactivity in your system. If the facts that I have assumed are not correct, then please advise me. Otherwise you can consider your reproductive risks to be the background risk of 3% for birth defects and 15% for miscarriage, providing you are young and healthy and have no reproductive problems or genetic and reproductive problems in your family. Robert Brent, MD, PhD

Answer posted on 21 May 2002. The information and material posted on this Web site is intended as general reference information only. Specific facts and circumstances may alter the concepts and applications of materials and information described herein. The information provided is not a substitute for professional advice and should not be relied upon in the absence of such professional advice specific to whatever facts and circumstances are presented in any given situation. Answers are correct at the time they are posted on the Web site. Be advised that over time, some requirements could change, new data could be made available, or Internet links could change. For answers that have been posted for several months or longer, please check the current status of the posted information prior to using the responses for specific applications.