Papillary thyroid microcarcinoma might progress during pregnancy.

Background: Papillary thyroid cancer occasionally occurs in women of childbearing age. As papillary thyroid microcarcinoma (PTMC) rarely grows or becomes clinically apparent, observation without surgery is an appropriate strategy for patients with low-risk PTMC. Human chorionic gonadotropin possesses weak thyroid-stimulating activity. The aim of this study was to assess the effect of pregnancy on PTMC. Methods: We studied 9 patients with PTMC who became pregnant between 2005 and 2011. Twenty-seven age-matched nonpregnant female PTMC patients from a database we used in our previous report served as controls. Tumor enlargement was defined as an increase in the diameter of the tumor of 3 mm or more. Results: PTMC enlargement occurred in 44.4% (4/9 patients) of the pregnant subjects, whereas it occurred only in 11.1% (3/27 patients) of the controls (p=0.0497). Three of the pregnant patients who exhibited tumor enlargement underwent surgery after delivery. No relationship was detected between the changes in th...