Endocrine Abstracts

Introduction: Thyroid dysfunction affect up to 5% of pregnant women and hypothyroidism complicates up to 3% of pregnancies, of which 0.3–0.5% is diagnosed as overt, 2.0–2.5% as subclinical hypothyroidism. Obesity in pregnant women may further contribute to the development of hypothyroidism and adversely affect the pregnancy. The aim of the study was to assess the risk of hypothyroidism in overweight and obese pregnant women on the basis of concentrations of TSH, free T₃, free T₄, and thyroid peroxidase antibodies (aTPO).

Methods: The study included 16 overweight/obese (BMI 25.2–34.9 kg/m²) pregnant women aged 22–41 years, patients of Gynecological Outpatient Clinic of the University Hospital. The control group consisted of 22 non-obese pregnant women with BMI in the normal range. In all subjects, serum concentrations of TSH, fT₄, fT₃ were determined twice during pregnancy and aTPO were measured in the first trimester.

Results: During the first trimester, median TSH concentration was higher 1.06 (0.47–2.38) mIU/l in overweight/obese than in non-obese women 0.65 (0.24–0.92) mIU/l (P<0.05). Median fT₃ and fT₄ did not differ significantly between both groups. aTPO concentrations were significantly increased in overweight/obese women (146.7 vs 32.8 IU/ml; P<0.05). At the second trimester, median TSH concentration was twofold higher in overweight/obese women compared to non-obese (1.63 vs 0.8 mIU/l; P<0.05); fT₃ and fT₄ did not differ significantly. Importantly, in overweight and obese women a more frequent incidence of pregnancy complications was observed. The percentage of pregnant women who developed hypothyroidism and were treated with L-thyroxine was higher in the study group compared to the control group.

Conclusion: Obesity is not uncommon in pregnant women and may increase the risk of hypothyroidism. It is important for doctors providing obstetric care to have wide understanding of the spectrum of thyroid disease occurring in pregnancy.