Maternal education and newborn thyroid-stimulating hormone level in a congenital hypothyroidism screening program

Objective: To examine the relationship between neonatal thyroid function and the formal education of mothers.Study design: Participants came from a population-based congenital hypothyroidism (CH) screening program in Tianjin, China.Methods: Of 66,390 registered births in 2015, 60,568 mothers and newborns had complete data. Mothers were categorized into one of four categories based on their educational attainment: (a) midschool or less; (b) high school or equivalent; (c) university; or (d) post graduate. Newborn thyroid-stimulating hormone (TSH) level was measured on day 3-7. Two neonatal groups were created using cutoffs of TSH > 10 μIU/ml and TSH > 20 μIU/ml. Odds ratios (OR) for CH risk by maternal education were estimated from logistic regression models after adjusting for potential confounders.Results: For TSH > 10 μIU/ml, the screen positive incidence rate for CH was 1:201 or 4.98 per 1000 births; for TSH > 20 μIU/ml, the incidence rate was 1:2222 or 0.45 per 1000 births. Screen positive incidence rates decreased with increasing maternal education level. Compared to mothers with a postgraduate education, the ORs (95% CI) for midschool or less, high school or equivalent, and university were 2.09 (1.08, 4.04), 1.45 (0.73, 2.90), and 1.61 (0.85, 3.06) using a cutoff of TSH > 10 μIU/ml. At the higher cutoff of TSH > 20 μIU/ml ORs (95% CI) for midschool or less and high school or equivalent were 3.05 (1.20,7.74) and 3.34 (1.24, 8.97), when compared to a composite reference category of university and postgraduate level education.Conclusion: Maternal education is inversely related to neonatal thyroid function though the mechanism remains unexplained.