ABSTRACT
Objective:To investigate the effects of maternal subclinical hypothyroidism (SCH) on preschoolers′ behavioral problems.Methods:Based on the Ma′ anshan Birth Cohort, pregnant women who had their first antenatal checkup in Maternal and Child Health Center in Ma′ anshan were recruited from May 2013 to September 2014. Data on demographic, obstetric information, and maternal exposure were collected. Women′s fasting venous blood in the first, second, and third trimesters of pregnancy was collected. The levels of thyroid hormones [thyrotropin (TSH), free thyroxine (FT 4)] and thyroid autoantibodies [thyroid peroxidase antibody (TPOAb), thyroglobulin antibody (TgAb)] in maternal blood were retrospectively detected by electrochemiluminescence immunoassay. Preschoolers′ behavioral problems were assessed by Achenbach Child Behavior Checklist (CBCL/1.5-5). Poisson regression models were adopted to examine the effect of maternal SCH on preschoolers′ internalizing and externalizing problems and the critical period. Results:In this study, the reference of maternal thyroid indexes was established (between 2.5 th and 97.5 th percentile). The reference of TSH in the first, second, and third trimester of pregnancy was 0.04-4.90 μIU/mL, 0.75-6.08 μIU/mL, and 0.58-5.59 μIU/mL respectively; and the reference of FT 4 was 13.19-23.27 pmol/L, 9.14-15.32 pmol/L, and 9.53-17.45 pmol/L respectively. In the first, second, and third trimester of pregnancy, the prevalence of SCH was found to be 2.0% (25/1 224), 1.6% (19/1 218), and 1.7% (21/1 220), respectively. After adjusting for confounding factors, maternal SCH in the first trimester was associated with the risk of anxiety and depression in preschool children ( OR=3.06, 95% CI 1.05-8.98). Maternal SCH in the second trimester was found to be associated with the risk of overreaction in preschool children ( OR=2.65, 95% CI 1.13-6.21). Conclusions:The establishment of thyroid hormones reference range for pregnant women in Ma′ anshan area is beneficial to the screening, diagnosis, and treatment of thyroid diseases during pregnancy in this area. Maternal SCH during pregnancy is associated with increased risk of behavioral problems in preschool children. In the first trimester, maternal SCH was associated with preschoolers′ anxiety and depression, and in the second trimester, maternal SCH was associated with preschoolers′ emotional reactivity.