Association Between Maternal Isolated Subclinical Hypothyroidism And The Emotional And Behavioral Development Of Preschoolers: A Birth Cohort Study

ObjectivesTo understand the association between maternal isolated hypothyroidism(SCH)and preschooler’s emotional and behavioral development,and to examine the potential moderation effect of maternal education.MethodsBased on the China-Anhui Birth Cohort,pregnant women who had their first prenatal checkup in the Ma’anshan Maternal and Child Health Hospital from October 2008 to October 2010 were recruited as the participants.Maternal baseline demographics and obstetric characteristics were collected at the checkup visit.Women’s serum was collected and retrospectively used to detect maternal thyroid function by chemiluminescence immunoassay.Data on childbirth was abstracted from the medical notes,including delivery mode,infant gender,gestational age and birth weight.Children’s feeding methods and caregiving patterns were collected,and the strengths and difficulties questionnaire was used to evaluate their emotional and behavioral development.The chi-square test was used to compare the prevalence of SCH under different characteristics of pregnant women and children,as well as to compare the rate of abnormalities in SDQ dimensions under different thyroid function status.Restricted cubic spline model was used to analyze the association between TSH concentration during pregnancy and preschooler’s SDQ scores.Binary logistic regression model was adopted to analyze the relationship between maternal isolated SCH and preschooler’s emotional and behavioral development.The regression models were re-run stratified by maternal education level to examine its potential moderation effect.ResultsThis study finally included 2 848 mother-infant pairs for data analysis.The prevalence of maternal isolated SCH was 8.0%(130/1 617),7.5%(86/1 150)and 7.4%(6/81)respectively within 12 weeks of gestation,at 13-20 weeks and 21-27 weeks of gestation.The average age of 2 848 preschool children was(4.3±0.5)years.Among the preschoolers,the rate of emotional,problems,conductive problem,hyperactivity problems,peer relationship problems,prosocial behavior problems and the overall difficult problems was 6.3%(180/2 848),7.8%(222/2 848),7.4%(212/2 848),2.6%(75/2 848),10.5%(300/2 848),and 7.6%(217/2 848),respectively.Restricted cubic spline regression analysis had shown that there existed a nonlinear relationship between TSH concentration in the first trimester and the risk of peer relationship problems,and between TSH concentration in the second trimester and the risk of conductive problems,showing an approximately "J"-shaped relationship.The poisson regression analysis had shown that maternal isolated SCH related to preschooler’s peer relationship problems within 12 weeks of gestation,OR(95%CI)being 2.514(1.029-6.144).Maternal isolated SCH was also associated with preschooler’s conductive problems at 13-20 weeks of gestation,and the OR(95%CI)was 2.255(1.284-3.958).After further stratifying by maternal educational level,it was found that maternal isolated SCH within 12 weeks of gestation was related with the risk of preschooler’s peer relationship problems in children whose mothers had low educational level,and the OR(95%CI)was 3.543(1.247-10.063).In children with lowly-educated mothers,there was a statistically significant relationship between maternal isolated SCH and conductive problems at 13-20 weeks of gestation,and the OR(95%CI)was 2.096(1.071-4.102).No statistically significant association between maternal isolated SCH and preschooler’s emotional and behavioral problems in children with highly-educated mothers.ConclusionMaternal isolated SCH within 20 weeks of gestation is associated with preschooler’s peer relationship problems and conductive problems.There might be a protective effect of maternal high education on maternal SCH and children’s emotional and behavioral abnormal development.