Alterations of thyroid volume and nodular size during and after pregnancy in a severe iodine-deficient area

The effects of pregnancy on thyroid nodules were investigated in a few number of studies. We aimed to evaluate the prevalence of thyroid nodules, the changes in size, volume and number of nodules during pregnancy and after delivery in pregnant women.

This prospective study was performed in a severe iodine-deficient area and included 83 pregnant women (mean age 30·4 ± 5·5 years). We evaluated thyroid hormone levels, ultrasound examination of thyroid and urine iodine concentration (UIE) at each trimester and at 3-month post-partum period (PP). All patients with thyroid nodules >1 cm underwent fine-needle aspiration biopsy (FNAB) after the last visit at the PP.

Twenty-six women had thyroid nodules on thyroid ultrasonography at the first trimester. The volume of single/dominant nodule showed enlargement during pregnancy and remained at the PP; however, it was not significant (first trimester: 0·83 ± 0·8 ml; second trimester: 0·92 ± 1 ml; third trimester: 0·99 ± 1·2 ml; PP: 0·92 ± 1·2 ml). The maximum diameter of single/dominant nodule in the third trimester of pregnancy (12·6 ± 5·4 mm) was greater than the first trimester (11·9 ± 4·8 mm) (P = 0·002). The number of nodules did not change during pregnancy. The mean TV increased during pregnancy and remained 3 months after delivery (P < 0·001), and the maximum value of TV was reached in the third trimester (14·2 ± 7·9 ml). FNAB results revealed a 6·6% prevalence of malignancy among the nodules.

Thyroid nodules were present in 30·1% of pregnant women. While size of the single/dominant thyroid nodule increased significantly during pregnancy, the number of nodules did not change.