Abstract:Objective: To establish the reference value range of trimester-specific thyroid hormone in pregnant women in our hospital, and to explore the impact of chronic lymphocytic thyroiditis (Hashimoto's thyroiditis) and hypothyroidism on pregnancy outcome. Methods: Levels of thyroid stimulating hormone (TSH), free thyronine (FT4) and free triiodothyronine (FT3) of pregnant women in our hospital from January 2018 to June 2019 were retrospectively collected and reference value ranges of different indexes in different trimesters were established. In addition, the pregnancy outcomes and neonate status of chronic lymphocytic thyroiditis, pregnancy hypothyroidism (TPO-Ab and TG-Ab negative) and normal pregnant women were retrospectively compared. Results: ①There were 1 216 women in the first trimester, 646 in the second trimester and 1287 in the third trimester. The reference value range of serum TSH in three trimesters were 0.04-3.73 μIU/mL, 0.10-4.03 μIU/mL and 0.68-4.32 μIU/mL, respectively; FT4 were 13.2-23.0 pmol/L, 9.8-17.4 pmol/L and 10.7-20.1 pmol/L; FT3 were 3.8-6.2 pmol/L, 3.3-5.7 pmol/L and 3.1-5.0 pmol/L.②There were 182 women in the Hashimoto's group, 180 in the hypothyroidism group and 180 in the normal control group. For the comparison of previous abortion rate in three groups, there were 38 patients (31.4%) in the the Hashimoto's group, which were significantly higher than 19 patients (17.4%) of the hypothyroidism group and 5 patients (4.8%) of the normal group, with statistically significant difference (P<0.05).③In the Hashimoto's thyroiditis group, 12 women had premature birth (6.6%) and 41 women had gestational diabetes mellitus (22.5%), which were higher than those in the antigen-negative hypothyroidism group (n=5, 2.8%; n=30, 16.7%) and in the normal group (n=3, 1.7%; n=20, 11.1%), with statistically significant differences (P<0.05).④In the Hashimoto's group, 12 women (6.6%) had fetal growth restriction, which was higher than that in the hypothyroidism group (n=4, 2.2%) and the normal group (n=2, 1.1%), with statistically significant differences (P<0.05). But there were no significant differences in birth weight, body length, Apgar score and blood gas analysis of pH and BE among three groups (P>0.05). Conclusion: The reference value range of thyroid function differs in different gestational periods. Therefore, establishing a reference range suitable for specific thyroid hormone is essential for screening and diagnosing thyroid diseases. Pregnancy complicated with chronic lymphocytic thyroiditis will increase the risk of miscarriage, premature delivery, gestational diabetes mellitus and fetal growth restriction. In order to diagnose thyroid diseases early and reduce the risk of adverse pregnancy outcome, diagnosis and treatment of Hashimoto's thyroditis and screening thyroid function and TPO-Ab and TG-Ab are essential during pregnancy.
