Maternal administration of 400μg of TRH determines maximal response of EPTA and this dose has been used in the majority of the randomized clinical trials to induce fetal pulmonary maturation. It remains unclear whether lower hormonal doses determine a similar response in FPTA. With the purpose of studying the response of FPTA to increasing doses of TRH, 32 pregnant women in preterm labor (25-34 weeks of gestation) were studied. Women were randomized to receive intravenously normal saline (n=6), 100μg (N=5), 200μg (n=12), 400μg (n=9) of TRH, administered 1-6 hours before delivery. The concentrations of thyrotropin (TSH), triodothyronine (T3), thyroxine(T4), prolactin (PRL), and growth hormone (GH) were determined in cord blood by RIA. Values are mean ± SD.*p<0.01 by ANCOVA (time as a covariate), Table Fetal TSH increased proportionally, correlating with the increasing doses of TRH. The different doses of TRH increased T3 above control levels, but no changes of T4 were observed. No correlation was seen in PRL and GH possibly because of the large dispersion of values. Although no significant differences were observed between groups with TRH, data suggests a proportional response of TSH at increasing doses of TRH. To conclude if this tendency is definitely significant a larger sample is required Supported by FONDECYT Grant N°193-0854.

Table
Full size table