Human fetal and cord serum thyroid hormones: developmental trends and interrelationships

Robert Hume, Judith Simpson, Caroline Delahunty, Hans van Toor, S. Y. Wu, Fiona L. R. Williams, Theo J. Visser, Scottish Preterm Thyroid Group

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    116 Citations (Scopus)


    Thyroid hormone is essential for fetal and neonatal development in particular of the brain, but little is known about regulation of fetal thyroid hormone levels throughout human gestation. The purpose of this study was to clarify developmental trends and interrelationships among T-4, free T-4 (FT4), thyroxine-binding globulin (TBG), TSH, T-3, rT(3), and T-4 sulfate (T4S) levels in cord and fetal blood sera ( n = 639, 15 - 42 wk gestation) and correlate infant levels ( 23 - 42 wk gestation) to maternal values ( n = 428, 16 - 45 yr) and those of nonpregnant women ( n = 233, 16 - 46 yr). In cord and fetal serum, T4, T3, and TBG levels increase with gestation until term; TSH, FT4, T4S, and rT(3) levels increase and peak in the late second/early third trimester and then decline to term; T-4/TBG ratios increase until late second trimester and plateau to term. Term cord sera TSH, TBG, and all iodothyronine levels, except T-3, are higher than nonpregnant women. In the third trimester, cord serum FT4, TSH, rT(3), and T4S levels are also higher than corresponding maternal levels, but T-4, T-3, and TBG levels are lower than maternal values. The late second/early third trimester is a critical transition period in fetal thyroid hormone metabolism, which may be interrupted by preterm birth and contribute to postnatal thyroid dysfunction.

    Original languageEnglish
    Pages (from-to)4097-4103
    Number of pages7
    JournalJournal of Clinical Endocrinology & Metabolism
    Issue number8
    Publication statusPublished - Aug 2004


    • Fetal blood chemistry
    • Postpartum period blood
    • Thyroid hormones blood


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