Prevalence of thyroid disorders in pregnant women with mild iodine deficiency

To assess the prevalence of thyroid disorders in a region with mild iodine deficiency, this study was undertaken in a randomized sample of pregnant women during different gestational periods. Evaluations were performed in 215 women: thyroid ultrasound scanning, thyroid stimulating hormone (TSH), free thyroxine (T4) and thyroid peroxidase (TPO) antibodies. At the time of participation in the study, some women (90/215) had been receiving 150-200 micrograms iodine. Hypothyroidism was found in four women (1.86%). Positive TPO antibodies were seen in 34 of 215 women (15.8%), and TPO antibody level over 150 mU/l was found in 9.8% (21/215). There was no significant difference between TSH levels in women with positive or negative TPO antibodies. There were no differences in TSH level between the women receiving and those not receiving iodine prophylaxis. The prevalence of goiter in 211 euthyroid women was found to be 24.2% (51/211). in the group with iodine prophylaxis, thyroid volume was found to be significantly lower (t = 2.5; p = 0.02) than in women who had not received it, or had started it during the second trimester. By comparison of history data on the prevalence of aborted pregnancy between the group with positive (26.5%; 9/34) and the group with negative TPO antibodies (14.3%; 26/181), no significant differences were found. We conclude that, in mild iodine deficiency, pregnancy is related to a high risk of goiter, which can be prevented by iodine prophylaxis. TPO antibody carrier status in pregnant women is probably not associated with a significant risk of thyroid dysfunction or spontaneous abortion.