Plasma thyroid hormones and prolactin in premature infants and their mothers after prenatal treatment with thyrotropin-releasing hormone.
We assayed TSH, triiodothyronine, free thyroxine, and prolactin (PRL) in plasma of women and infants participating in a trial of prenatal thyrotropin-releasing hormone (TRH) treatment for prevention of newborn lung disease. Women in labor at 26-34 wk of gestation received 400 micrograms of TRH i.v. every 8 h (one to four doses) plus 12 mg betamethasone (one or two doses); controls received saline plus betamethasone. Mean cord concentrations in control infants were TSH 9.7 mU/L, triiodothyronine 0.6 nmol/L (40.2 ng/dL), free thyroxine 14.4 pmol/L (1.13 ng/dL), and PRL 67.6 micrograms/L. TRH increased maternal plasma TSH by 100% at 2-4 h after treatment and decreased levels by 28-34% at 5-36 h. In cord blood of treated infants delivered at 2-6 h, TSH, triiodothyronine, and PRL were all increased about 2-fold versus control, and free thyroxine was increased 19%; the response was similar after one, two, three, or four doses of TRH. In treated infants delivered at 13-36 h, cord TSH and triiodothyronine levels were decreased 62 and 54%, respectively, and all thyroid hormones were lower after birth at 2 h of age versus control. We conclude that prenatal TRH administration increases thyroid hormones and PRL in preterm fetuses to levels similar to those normally occurring at term. Pituitary-thyroid function is transiently suppressed after treatment to a greater extent in fetus than mother, and infants born during the early phase of suppression do not have the normal postnatal surge in thyroid hormones.
Ballard
P L
PL
Department of Pediatrics and Obstetrics and Gynecology, Mount Zion Hospital, San Francisco, California 94143.
Ballard
R A
RA
Creasy
R K
RK
Padbury
J
J
Polk
D H
DH
Bracken
M
M
Moya
F R
FR
Gross
I
I
D001623:Betamethasone / Q000008:administration & dosage; D005260:Female; D005312:Fetal Blood / Q000378:metabolism; D006801:Humans; D007230:Infant, Low Birth Weight; D007231:Infant, Newborn; D007234:Infant, Premature; D008431:Maternal-Fetal Exchange; D011247:Pregnancy; D011388:Prolactin / Q000097:blood*; D012127:Respiratory Distress Syndrome, Newborn / Q000517:prevention & control; D013963:Thyroid Hormones / Q000097:blood*; D013972:Thyrotropin / Q000097:blood; D013973:Thyrotropin-Releasing Hormone / Q000008:administration & dosage / Q000494:pharmacology*; D013974:Thyroxine / Q000097:blood; D014284:Triiodothyronine / Q000097:blood
D013963:Thyroid Hormones; D014284:Triiodothyronine; D013973:Thyrotropin-Releasing Hormone; D011388:Prolactin; D013972:Thyrotropin; D001623:Betamethasone; D013974:Thyroxine