Previous studies have found that increased TSH levels but without thyroxine deficiency are more common in preterm and low-birth-weight infants.40,41 This phenomenon might be related to fetal growth restriction that changes the amount and isoform of hormone receptors in the immature brain and alters the function of the hypothalamus-pituitary-thyroid axis.40 The clinical significance of this rising TSH pattern remains unclear,42 but an association with neurodevelopment was suggested by our findings. The gene discussed is NR4A1; the disease is fetal growth restriction.