[Analysis of pregnancy-related adverse outcomes in patients with severe hypothyroidism during pregnancy]

Objective: To analyze the pregnancy-related adverse outcomes in patients with severe hypothyroidism during pregnancy. Methods: Using cross-sectional study, a total of 47 pregnant women with severe hypothyroidism in the Peking University First Hospital from January 2007 to December 2020 were retrospectively collected by electronic case system. According to the occurrence of adverse pregnancy events (defined as any pregnancy complication or adverse maternal-fetal/neonatal outcomes), the patients were divided into pregnancy-related adverse outcomes group (n=33) and no pregnancy-related adverse outcomes group (n=15). The demographic data, thyroid function and thyroid autoantibody levels during pregnancy, pregnancy complications and maternal-fetal/neonatal outcomes of the two groups were recorded and analyzed. Results: The age of severe hypothyroidism women was (30.5±4.1) years. The median of gestational week at delivery was 38.6 (36.3, 39.9) weeks, the median of gestational week for diagnosis was 7.0 (6.0, 8.8) weeks, the median of the highest TSH level was 32.7(23.1,60.2)mU/L and the period of reaching the target TSH level for the first time was 6.0(4.0, 10.0)weeks. Most cases (82.5%, 33/40) had thyroid autoimmunity. All women were treated with levothyroxine (L-T₄) during pregnancy. A total of 37 cases (77.1%, 37/48) of them obtained the recommended target values. Fourty cases (83.3%, 40/48) gave birth. The birth weight of newborns was (3 041±452) g, the body length was (49.4±2.1) cm, and the head circumference was (33.6±0.7) cm. The period of reaching to target TSH level for the first time in patients without pregnancy-related adverse outcomes was shorter [5.0 (3.0, 9.0) vs 8.0 (4.5, 12.5) weeks) ] (P=0.033), and the times of thyroid function monitoring were more frequent [ (8.2±3.5) vs (6.0±3.6) times] (P=0.049) than the group with pregnancy-related adverse outcomes. Conclusions: The incidence of pregnancy complications and adverse maternal-fetal/neonatal outcomes is high in patients with severe hypothyroidism during pregnancy. Intense follow-up, treatment and restoration of euthyroidism as prompt as possible may improve pregnant outcomes.