Response of the maternal, fetal, and neonatal pituitary-thyroid axis to thyrotropin-releasing hormone

Fernando Moya, Patricia Mena, Felipe Heusser, Arnaldo Foradori, Enrique Paiva, Ricardo Yazigi, Patricio Michaud, Ian Gross

Research output: Contribution to journalArticle

Abstract

Thyrotropin releasing hormone (TRH) readily crosses the placenta and stimulates the fetal pituitary. We studied the response of the maternal and fetal pituitary-thyroid axes to TRH and the influence of prenatal exposure to TRH on the physiological postnatal increase in thyrotropin (TSH) and triiodothyronine (T3) in the neonate. Twenty-six pregnant women received TRH (400 or 600 ng) intravenous or saline (controls) either 2 or 12 h before elective cesarean section at term. Administration of 400 jug of TRH resulted in significant elevations of maternal TSH (15.7 ± 2.9 versus 3.2 ± 0.4 μU/ml, р < 0.01) and prolactin (416 ± 94 versus 223 ± 41 ng/ml, p < 0.05) 2 h later. Maternal T3 remained unchanged. A higher dose of TRH (600 μg) produced comparable results. Maternal administration of TRH (400 jug) 2 h before delivery resulted in significant increases in fetal TSH and T3 over controls (21.1 ± 3.7 versus 4.8 ± 1.0 μU/ml, and 132 ± 12 versus 64 ± 9 ng/dl, p < 0.01, respectively). Cord blood hormone levels 12 hours after TRH administration were similar to controls. Higher doses of TRH did not produce further increases in fetal TSH or T3. Control and treated neonates demonstrated similar physiological postnatal increases in TSH and T3, suggesting that prior exposure to TRH did not blunt this response. These data suggest that maternal administration of TRH is an effective way of increasing fetal T3 levels, and that this treatment does not inhibit the postnatal surge in TSH and T3.

Original languageEnglish (US)
Pages (from-to)982-986
Number of pages5
JournalPediatric research
Volume20
Issue number10
DOIs
StatePublished - Oct 1986

ASJC Scopus subject areas

  • Pediatrics, Perinatology, and Child Health

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