To test the hypothesis that term small for gestational age (SGA) neonates exhibit higher thyroid-stimulating hormone (TSH) concentrations and an increased incidence of congenital hypothyroidism.
This retrospective cohort study included all term neonates screened in Wisconsin in 2015 and 2016. The cohort was divided based on SGA status, defined as birth weight percentile <10 calculated from WHO 0-2 years sex-specific growth charts. TSH concentration on first newborn screening performed between birth and 96 hours of life and incidence of congenital hypothyroidism were both compared between groups.
A total of 115 466 of term neonates including 11 498 (9.96%) SGA neonates were included in the study. TSH concentration and incidence of congenital hypothyroidism was significantly higher in the SGA group but only TSH concentration remained significant when adjusted for potential confounding variables.
Our data do not support a higher incidence of congenital hypothyroidism in term SGA neonates after adjusting for potential confounders. However, TSH concentration was higher in term SGA neonates compared with term non SGA neonates. The effects of mild thyroid hormone dysfunction on neurodevelopmental outcomes and development of chronic medical conditions merit long term study.

Copyright © 2021. Published by Elsevier Inc.