Objective: To examine the relationship between specific thyroid abnormalities (subclinical hypothyroidism, hypothyroxinaemia or elevated thyroid peroxidase antibody titres) in women during pregnancy and the subsequent neuropsychological development of their offspring.
Design/patients: Serum was collected from 1268 women at 16-20 weeks of gestation and thyroid stimulating hormone (TSH), total thyroxine (tT(4)), free thyroxine (fT(4)), and Thyroid peroxidase antibodies (TPOAb) levels were measured. Thyroid function reference ranges specific for pregnancy were used to screen for thyroid abnormalities. Patients with isolated subclinical hypothyroidism (18 cases), hypothyroxinaemia (19 cases), and those who were euthyroid patients with elevated titres of TPOAb (34 cases) were identified. One hundred and forty-two euthyroid and TPOAb-negative women matched for gestational age from the same cohort were selected as controls.
Measurements: Intellectual and motor development score evaluations were performed on the children from the pregnancies at 25-30 months of age.
Results: Children of women with subclinical hypothyroidism, hypothyroxinemia and elevated TPOAb titres had mean intelligence scores 8.88, 9.30 and 10.56 points lower than those of the control group (P = 0.008, P = 0.004 and P = 0.001, respectively); mean motor scores were 9.98, 7.57 and 9.03 points lower than those of the controls [P < 0.001, P = 0.007 and P < 0.001, respectively (t-test)]. Unconditional multivariate logistic regression analysis showed that increased maternal serum TSH, decreased maternal serum tT(4), and elevated maternal TPOAb titres were separately associated with lower intelligence scores (ORs 15.63, 12.98, and 6.69, respectively) and poorer motor scores (ORs 9.23, 5.52, and 8.25, respectively).
Conclusions: Intellectual and motor development of children at 25-30 months of age is separately associated with abnormalities of maternal thyroid at 16-20 weeks gestation. Maternal subclinical hypothyroidism, hypothyroxinaemia or euthyroidism with elevated TPOAb titres were all statistically significant predictors of lower motor and intellectual development at 25-30 months.