Antenatal corticosteroids for threatened labour facilitate thyroid maturation among preterm neonates

Abstract

Objective: To examine the effect of antenatal corticosteroids (ANS) on the maturation of thyroid function in the preterm infants.

Context: ANS reduce mortality and morbidities in preterm neonates. Organ maturation by the glucocorticoids is the key, at least in part. However, the effect of ANS on thyroid is controversial.

Patients: A study group of 99 very low birthweight neonates (<34 weeks' gestational age) with the exception of those born more than 7 days after ANS administration were divided into a complete group (n = 49) whose mothers completed two doses of betamethasone and who were born more than 24 hours after the completion of ANS administration, and an incomplete group (n = 50) who were not exposed to any ANS or were born within 24 hours after the completion of ANS administration. Serum-free thyroxine and thyroid-stimulating hormone (TSH) levels were measured, and thyrotropin-releasing hormone (TRH) stimulation tests were performed at about 2 weeks of age.

Results: The incidence of hyperthyrotropinaemia (TSH > 15 mIU/L) in the complete group was significantly lower than in the incomplete group (6% vs 22%, P = .023). Exaggerated responses to TRH tests were more frequent in the incomplete group (17% vs 44%; P = .053). TSH₃₀ was significantly lower in the complete group, (P = .046). Multivariate logistic regression analysis showed that the incidence of hyperthyrotropinaemia was associated with complete ANS administration (adjusted odds ratios 0.39).

Conclusions: ANS administration might facilitate thyroid maturation in preterm neonates.

Keywords: antenatal corticosteroids; cortisol; preterm; thyroid; thyrotropin-releasing hormone.