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Relations between the fetal circulation and pituitary‐thyroid function
Author(s) -
THORPEBEESTON J. GUY,
NICOLAIDES KYPROS H.,
SNIJDERS ROSALINDE J. M.,
FELTON CARL V.,
VYAS SANJAY,
CAMPBELL STUART
Publication year - 1991
Publication title -
bjog: an international journal of obstetrics and gynaecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.157
H-Index - 164
eISSN - 1471-0528
pISSN - 1470-0328
DOI - 10.1111/j.1471-0528.1991.tb15371.x
Subject(s) - circulation (fluid dynamics) , fetal circulation , thyroid function , function (biology) , fetus , medicine , thyroid , endocrinology , biology , pregnancy , physics , microbiology and biotechnology , mechanics , placenta , genetics
Objective— To study the relation between changes in the fetal thyroid hormone and thyroid stimulating hormone (TSH) concentrations and alterations in the fetal circulation as assessed by Dopplcr ultrasound. Design— A cross‐sectional study of small for gestational age (SGA) and red‐cell isoimmunized fetuses undergoing cordocentesis and Dopplcr studies for the assessment and determination of fetal karyotype, acid‐base balance and hac‐moglobin concentration. Setting— Harris Birthright Research Centre for Fetal Medicine, King's College, London. Subjects— 38 growth retarded and 38 red‐cell isoimmunised fetuses. Interventions— Cordoccntesis. Main outcome measures— Serum TSH total and free thyroxine (T4, FT4) and total and free triiodothyronine (T3, FT3) concentrations; middle cerebral artery (MCAVm) and dcsccnding thoracic aorta (AoVm) mean blood velocities; fetal Po2 and haemoglobin concentration (Hb). Results— Delta values (8) calculated as the number of SDs from the respective normal mean for gestation were used to compare the results with those from a previous study of normal fetuses. Mean AoVm was increased in the isoimmu‐nized fetuses ( P < 0.001 ) but decreascd in the SGA fetuses ( P < 0.001 ). Mean MCAVm was increascd in both groups ( P < 0.01 ; P < 0.001 ). There were signifi‐cant associations between the gestational age adjusted values for TSH and MCAVm ( r = 0.23 , P < 0.05 ) and between T4, FT4 or FT3 and AoVm ( r = 0.41 , P < 0.01 ; r = 0.50 , P < 0.001 ; r = 0.36 , P < 0.01 respectively). In addition, T4 and FT4 were associated with 8Po2 and 8Hb. Conclusion— In the hypoxaemic hypoxia of growth retardation and the anaemic hypoxia of rhesus disease there are significant associations between changes in fetal thyroid hormone concentrations and changes in fetal blood flow as assessed by Dopplcr. Irrespective of whether altercd blood flow is the cause or cffect of changes in thyroid hormone concentrations, the observed changes could have beneficial effects for fetal survival, in the presence of a hostile intrauterine environment.