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Thyroid Nodules Enlarge and Are More Common During Pregnancy


Updated January 24, 2009

In a study published in 2002 in The Journal of Clinical Endocrinology & Metabolism, Chinese researchers looked at the incidence of thyroid nodules during pregnancy to determine whether pregnancy induces the formation of nodules. A total of 221 women in the first trimester of pregnancy were studied. In the group, 34 (15.3%) had thyroid nodules, and among them, 12 (5.4%) had more than one nodule.

Typically, thyroid nodules enlarge during pregnancy, in some cases to almost double their initial size, and remain enlarged as long as 3 months after delivery. New nodules appeared in 25 (11.3%) of the women as their pregnancies advanced, leaving the total incidence of thyroid nodular disease at 24.4% by 3 months postpartum.

No thyroid malignancies were detected.

The researchers concluded that pregnancy can increase the size of pre-existing thyroid nodules, trigger formation of new thyroid nodules and possibly increase the risk of developing multinodular goiter later in life. In general, pregnancy is a time when thyroid nodules become more common in women.


Kung,A. W. C. et. al. "The Effect of Pregnancy on Thyroid Nodule Formation," The Journal of Clinical Endocrinology & Metabolism, Vol. 87, No. 3 1010-1014, 2002, Online

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