I am 29 years old and recently had a miscarriage. I have been taking medication for an underactive thyroid since 1992. Could this have caused my miscarriage? What steps should I take to make sure that I can have a baby? --Kristina

The most likely cause of a single miscarriage is a chromosomally abnormal pregnancy. This is usually caused by a bad egg or sperm. Mistakes can be made as the fertilized egg divides the first few times.

Thyroid problems can interfere with hormone levels and may increase the risk of miscarriage if thyroid levels are markedly abnormal. If the problem has been corrected properly with thyroid hormone replacement, it should not contribute to the risk of miscarriage.

Women who have lost more two or more pregnancies should undergo a more extensive evaluation looking for causes of recurrent pregnancy loss before attempting to conceive again.