The New England Journal of Medicine
e-mail icon  FREE NEJM E-TOC    HOME   |   SUBSCRIBE   |   CURRENT ISSUE   |   PAST ISSUES   |   COLLECTIONS   |    Advanced Search
Sign in | Get NEJM's E-Mail Table of Contents — Free | Subscribe
 
Original Article
PreviousPrevious
Volume 324:532-536 February 21, 1991 Number 8
NextNext

Maturation of the secretion of thyroid hormone and thyroid-stimulating hormone in the fetus
JG Thorpe-Beeston, KH Nicolaides, CV Felton, J Butler, and AM McGregor

 Sign up for free e-toc
 

Tools and Services
-Add to Personal Archive
-Add to Citation Manager
-Notify a Friend
-E-mail When Cited

More Information
-PubMed Citation
Abstract

BACKGROUND. Data on human fetal thyroid function have largely been derived from histologic studies or studies of cord-blood samples obtained at hysterotomy or delivery. These data may not represent true normal values. Cordocentesis (ultrasound-guided blood sampling from the umbilical cord) is a technique that allows investigation of physiologic processes in fetuses not under stress. METHODS. We measured serum thyroid-stimulating hormone, total and free thyroxine (T4), total and free triiodothyronine (T3), and thyroxine-binding globulin in blood samples from 62 fetuses. The samples were obtained by cordocentesis (n = 58) or cardiocentesis (n = 4) at 12 to 37 weeks of gestation. Maternal serum samples were obtained immediately before fetal blood sampling. RESULTS. Fetal serum thyroid-stimulating hormone, thyroxine-binding globulin, and total and free T4 and T3 concentrations increased significantly with the length of gestation (P less than 0.001). The only significant association among these variables, independent of the length of gestation, was between thyroid-stimulating hormone and free T4 (P less than 0.0001). Maternal serum concentrations of these variables did not change during gestation, and there was no significant relation between fetal and maternal values. Most fetal serum concentrations of thyroid-stimulating hormone were higher, whereas most serum total and free T3 concentrations were lower than the respective values for normal adults. The fetal serum total T4, free T4, and thyroxine-binding globulin values reached the level of the mean adult values at approximately 36 weeks of gestation. CONCLUSIONS. The increases in fetal serum concentrations of thyroid-stimulating hormone, thyroxine-binding globulin, and total and free T4 and T3 during gestation reflect increasing maturation of the pituitary, thyroid, and liver. The finding of increasing fetal serum concentrations of thyroid-stimulating hormone in the presence of increasing thyroid hormone concentrations suggests that the sensitivity of the fetal pituitary gland to negative feedback is limited or is counterbalanced by increasing stimulation by thyrotropin-releasing hormone from the hypothalamus.


Source Information

Department of Obstetrics and Gynaecology, Harris Birthright Research Centre for Fetal Medicine, London, United Kingdom.


This article has been cited by other articles:



HOME  |  SUBSCRIBE  |  SEARCH  |  CURRENT ISSUE  |  PAST ISSUES  |  COLLECTIONS  |  PRIVACY  |  HELP  |  beta.nejm.org

Comments and questions? Please contact us.

The New England Journal of Medicine is owned, published, and copyrighted © 2008 Massachusetts Medical Society. All rights reserved.