| ObjectivesWe aim to investigate the association between maternal subclinical hypothyroidism（SCH）and preschoolers’internalizing and externalizing behavioral problems,the critical period and gender differences.We also intend to examine the role of maternal cognition in moderating the effect of SCH on preschoolers’behavioral development.MethodsBased on Ma’anshan Birth Cohort（MABC）in China,pregnant women were recruited at their first antenatal checkup in Ma’anshan Maternal and Child Health Hospital from May 2013 to September 2014.Data on demographic and obstetric information were collected by questionnaire survey.Women’s fasting venous blood in the first,second and third trimesters of pregnancy was collected.The levels of thyroid hormones（TSH,FT4）and thyroid autoantibodies（TPOAb,Tg Ab）in maternal blood were retrospectively detected by electrochemiluminescence immunoassay.Maternal cognitive levels were assessed by Wechsler Adult Intelligence Scale-Revised by China（WAIS-RC）.Preschoolers’behavioral problems were assessed by Achenbach Child Behavior Checklist（CBCL/1.5～5）.Independent sample T tests were used for continuous variables,and Pearson χ ~2tests or Fisher’s exact tests were used for classification variables to analyze the distribution of different maternal and child characteristics in the normal group and SCH group,respectively.Poisson regression models were adopted to examine the effect of maternal SCH on preschoolers’internalizing and externalizing problems and the critical period.The numbers of mothers with SCH in the first,second,and third trimesters of pregnancy were merged,and mothers with SCH in any one or more trimesters of pregnancy were defined as having SCH during pregnancy.Further stratified analyses were carried out according to children’s gender and maternal cognitive levels.ResultsIn this study,the reference of maternal thyroid indexes was established（between2.5th and 97.5th percentile）.The reference of TSH in the first,second and third trimesters of pregnancy was（0.04～4.90）μIU/m L,（0.75～6.08）μIU/m L and（0.58～5.59）μIU/m L,respectively;and the reference of FT4was（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 trimesters of pregnancy,the prevalence of SCH was found to be2.0%（25/1224）,1.6%（19/1218）and 1.7%（21/1220）,respectively.After adjusting for confounding factors,maternal SCH in the first trimester was associated with the risk of offspring’s anxious/depressed（OR=3.06,95%CI:1.05-8.98）,and maternal SCH in the second trimester was associated with the risk of offspring’s emotionally reactive（OR=2.65,95%CI:1.13-6.21）.Maternal SCH during pregnancy was associated with the risk of anxious/depressed（OR=3.05,95%CI:1.02-9.17）and somatic complaints（OR=2.50,95%CI:1.32-4.74）in girls.SCH in mothers with low cognitive levels during pregnancy was associated with the risk of offspring’s anxious/depressed（OR=5.11,95%CI:1.15-2.73）.ConclusionsMaternal SCH may increase the risk of behavioral problems in preschool children in both the first and second trimesters of pregnancy,especially in girls and mothers with low cognitive levels. |
