A randomized, controlled trial of antepartum thyrotropin-releasing hormone and betamethasone in the prevention of respiratory disease in preterm infants. Results of controlled double-blind study of thyroid replacement in very low-birth-weight premature infants with hypothyroxinemia. Antenatal thyrotropin-releasing hormone to prevent lung disease in preterm infants. North American Thyrotropin-Releasing Hormone Study Group. Postnatal triiodothyronine replacement and respiratory distress syndrome of the preterm infant. Respiratory disease in very-low-birthweight infants after prenatal thyrotropin-releasing hormone and glucocorticoid. TRH Study Group. The effect of antenatal corticosteroid therapy on pregnancies complicated by premature rupture of membranes. Collaborative trial of prenatal thyrotropin-releasing hormone and corticosteroids for prevention of respiratory distress syndrome. Collaborative Santiago Surfactant Group. Postnatal thyroxine supplementation in infants less than 32 weeks' gestation: effects on pulmonary morbidity. Two trials of antenatal thyrotrophin-releasing hormone for fetal maturation: stopping before the due date. Antenatal TRH Trial and the Thyroneth Trial Groups.
The objective was to investigate whether the addition of thyrotropin-releasing hormone to antepartum betamethasone further reduces the incidence of respiratory disease in preterm infants.
                A randomized, placebo-controlled, double-blind trial of antepartum thyrotropin-releasing hormone (400 micrograms given intravenously four times) and betamethasone (5 mg given intramuscularly four times) was conducted in 378 mothers likely to be delivered between 24 and 32.6 weeks' gestation. Statistical analysis was by relative risk, chi 2, t tests, and multiple logistic regression analysis.
                Four hundred five live-born infants were delivered. In infants without lethal abnormalities delivered between 24 hours and 10 days from entry (n = 175) the incidence of respiratory distress syndrome was reduced from 52% to 31% (relative risk 0.61, 95% confidence interval 0.41 to 0.89) and that of severe respiratory distress syndrome from 42% to 20% (relative risk 0.48, 95% confidence interval 0.29 to 0.78) in the placebo and thyrotropin-releasing hormone groups, respectively. The number of deaths fell from 14 to one (relative risk 0.08, 95% confidence interval 0.01 to 0.63). The incidence of chronic lung disease was not significantly different, but that of an adverse outcome (chronic lung disease or death by 36 weeks' gestation) fell from 29% in the placebo group to 16% with thyrotropin-releasing hormone (relative risk 0.55, 95% confidence interval 0.31 to 0.99).
                The addition of thyrotropin-releasing hormone to antepartum glucocorticoid treatment reduces the incidence of respiratory distress syndrome and improves survival in preterm infants. The nature of hypothyroxinemia in sick very low-birth-weight (VLBW) infants was evaluated by assessment of the hypothalamic-pituitary axis and by the clinical response to thyroxine (T4) therapy. Twenty-three very low-birth-weight infants of gestational age 26 to 28 weeks, whose serum T4 concentrations were 4 micrograms/dL on two occasions, and thyrotropin less than 20 microU/mL, were included in a double-blind study. Following a thyrotropin-releasing hormone stimulation test, babies were given either T4 or placebo. Nine babies were thyrotropin-releasing hormone tested prior to therapy; four babies, two from each group, were tested 1 to 2 weeks after therapy. In 11 untreated babies, mean base line serum thyrotropin of 7.0 +/- 1.4 rose to 23.7 +/- 4.1 microU/mL in 30 minutes. This response was not significantly greater than the observed response in full-term babies, 23.7 +/- 4.1 v 16.6 +/- 0.97 microU/mL, respectively, P greater than .05. In two babies treated with T4 the thyrotropin response to thyrotropin-releasing hormone was completely suppressed. Serial serum T4 determinations showed normalization in both groups after a similar time interval. There was no beneficial effect of T4 therapy on growth of head circumference, length, or weight. Developmental data revealed no significant differences in the mental, motor, or gross neurologic outcome in the treated and nontreated infants after 1 year of follow-up. These observations imply that hypothyroxinemia in sick preterm infants is not a direct consequence of hypothyroidism. Despite the lack of demonstrable short-term beneficial effects of T4 therapy, follow-up studies are necessary to resolve the question of long-term benefits. Pulmonary disease is common in preterm infants, despite antenatal glucocorticoid therapy. The addition of antenatal thyrotropin-releasing hormone therapy has been reported to decrease pulmonary morbidity in these infants.
                We enrolled 996 women at 13 North American centers who were in preterm labor at <30 weeks' gestation in a double-blind, placebo-controlled, randomized trial of antenatal thyrotropin-releasing hormone, given intravenously in four doses of 400 microg each at eight-hour intervals. The primary outcome was chronic lung disease or death of the infant on or before the 28th day after delivery, and secondary outcomes were respiratory distress syndrome and chronic lung disease or death at 36 weeks' postmenstrual age. Complete data were available for 981 women and their 1134 live-born infants. The 769 infants born at < or = 32 weeks' gestation were defined as the group at risk.
                There were no significant differences between the at-risk treatment and placebo groups in mean (+/-SD) birth weight (1109+/-354 vs. 1097+/-355 g), gestational age (27.9+/-2.1 vs. 27.9+/-2.1 weeks), sex, or race. The frequencies of respiratory distress syndrome (66 percent vs. 65 percent), death at 28 days (11 percent vs. 11 percent), chronic lung disease or death at 28 days (45 percent vs. 42 percent) and at 36 weeks (32 percent vs. 34 percent), and other neonatal complications as well as the severity of lung disease were not significantly different in the at-risk treatment and placebo groups. Similarly, there were no differences in outcome between the treatment and placebo groups for the infants born at >32 weeks' gestation.
                In preterm infants at risk for lung disease, antenatal administration of thyrotropin-releasing hormone and glucocorticoid is no more beneficial than glucocorticoid alone. Improvements in the management of respiratory distress syndrome (RDS) include pre- and postnatal stimulation of pulmonary maturity, and triiodothyronine (T3) is believed to influence directly surfactant production. Its circulating levels are low in premature infants with RDS probably due to a low thyroxine T4-T3 hepatic conversion mechanism. While a state of hypotriiodothyroninemia exists at birth, we studied the influence of postnatal intravenous T3 administration on the course of RDS in preterm infants of less than 32 weeks' gestation. Fifty preterm infants with RDS were studied (mean gestational age 30.4 +/- 1.2 weeks and birth weight 1,180 +/- 220 g). They were at random assigned to treatment with 50 micrograms L-T3 (Thyrotardin) or to the control group. Mortality rate, peak oxygen concentrations, duration of artificial ventilation and development of major complications of RDS were the criteria to estimate the influence of T3 treatment on RDS. We failed to detect a statistically significant difference between the two groups in all of the mentioned criteria except for FiO2 concentrations required to maintain PaO2 between 50 and 60 mm Hg (p less than 0.05). These observations suggest a relative beneficial effect of T3 replacement on the course of RDS in preterm infants of less than 32 weeks of gestation. Although prenatal glucocorticoid treatment reduces neonatal respiratory morbidity, respiratory distress syndrome and chronic lung disease (CLD) develop in many very-low-birthweight infants despite therapy. To investigate the effect of additional prenatal treatment with thyrotropin-releasing hormone (TRH), we did a multicentre, blinded, randomised trial. 404 women with threatened preterm delivery at less than 32 weeks' gestation received betamethasone plus TRH (4 doses of 400 micrograms 8-hourly) or betamethasone plus placebo. 103 infants who were fully treated and of less than 1500 g birthweight were evaluated during the neonatal period. TRH treatment (55 infants) did not affect the total incidence of respiratory distress syndrome (47% vs 58% in controls) or of severe respiratory distress syndrome (13% vs 25% in controls, p = 0.11). CLD (defined as requirement for supplemental oxygen at 28 days after birth) developed in significantly fewer TRH-treated infants (18% vs 44% of controls, p less than 0.01). The unadjusted relative risk of CLD with TRH therapy was 0.40 (95% CI 0.26-0.80, p less than 0.05), and this was not materially changed after adjustment for potentially modifying variables. There were significantly fewer adverse outcomes, defined as death or continuing oxygen requirement, in the TRH group than in the steroid-alone group both at 28 days and when infants reached 36 weeks' postconceptional age. The incidence of other complications of prematurity was similar in the two groups. Prenatal TRH reduces the incidence of chronic lung disease among betamethasone-treated infants. This study was carried out to examine the effect of antenatal corticosteroid therapy on pregnancies complicated by premature rupture of membranes (PROMs). For this purpose, 139 patients with a singleton pregnancy (27-34 weeks of gestation) complicated by PROMs were evaluated prospectively during the period January 1997 to February 1999 at two Jordanian military hospitals (Prince Rhashed and Prince Zaid). Patients were allocated into two groups; Group 1 included 72 patients treated with dexamethsone (24 mg divided into 4 doses 12 hours apart), and Group 2 which included 67 patients whoreceived no treatment (control group). All women were examined clinically and the diagnosis of PROMs was demonstrated using vaginal speculum, nitrazine paper examination and ultrasonography. All neonates were evaluated clinically, radiologically, and by laboratory investigations. Pearson's Chi-square and Fisher's exact tests were used to assess the significance of differences between the two study groups. Respiratory distress syndrome (RDS), necrotizing enterocolitis (NEC), intraventricular haemorrhage (IVH), and days of hospital stay were significantly reduced in premature infants of the corticosteroid treated women compared with the controls (p<0.04, p<0.04, p<0.04, and p<0.05, respectively). The perinatal mortality was significantly decreased among the corticosteroid treated group in the gestational subgroups 31-32 and 33-34 weeks (p<0.04), and in all birth weight subgroups (p<0.03). RDS was statistically a significant factor which resulted in increased perinatal mortality in the control group (p=0.02). Regarding the occurrence of postpartum endometritis there was a statistically significant increase among the corticosteroid treated group compared with the controls (p<0.04). Conclusion: Antenatal corticosteroid therapy in pregnancies complicated by PROMs has a positive influencing effect on premature infants between 31 and 34 weeks of gestation, decreasing significantly the perinatal morbidity and mortality. It should be used with particular relevance to the developing world where surfactant is not available or where neonatal intensive care units are lacking. Our purpose was to determine whether adding antenatal thyrotropin-releasing hormone to prenatal corticosteroids reduces the frequency of respiratory distress syndrome.
                A randomized, multicenter, double-blind, placebo-controlled trial was conducted of thyrotropin-releasing hormone (400 micrograms intravenously every 8 hours four times) in women with singleton pregnancies < 33 weeks of gestation who received antenatal betamethasone (12 mg intramuscularly every 24 hours two times). Neonates weighing < 1.0 kg received prophylactic surfactant and those above that weight received rescue therapy.
                One hundred ninety women received thyrotropin-releasing hormone and 180 were given placebo. There were no differences in the frequency of respiratory distress syndrome (relative risk 1.17 [95% confidence interval 0.93 to 1.48]), use of oxygen at age 28 days (1.14 [0.80 to 1.62]), or neonatal mortality (1.05 [0.79 to 1.38]). Air leaks were more frequent in the thyrotropin-releasing hormone group (1.57 [1.23 to 2.01]).
                The combination of antenatal thyrotropin-releasing hormone and corticosteroids does not reduce the frequency of respiratory distress syndrome or improve the outcome of preterm neonates compared with the use of corticosteroids alone. Transient hypothyroxinemia in premature newborns has been linked with poor neonatal outcomes. We designed this study to evaluate the effects of early thyroxine (T4) administration in the premature infant.
                A total of 49 newborns less than 32 weeks' gestation, were randomized in a double-blind, placebo-controlled trial. Within the first 48 hours of life, T4 (10 or 20 micrograms/kg; intravenous or through nasogastric tube, respectively) was administered for a total of 21 days. Chronic lung disease, the primary outcome variable, was defined by oxygen dependency at 28 days of life.
                The incidence of chronic lung disease, death, grade III or IV intraventricular hemorrhage, periventricular leukomalacia, and sepsis was not different in the placebo and treated groups.
                Early T4 supplementation in preterm newborns less than 32 weeks' gestation does not decrease the incidence of chronic lung disease or other complications of prematurity. To determine whether the addition of antenatal thyrotrophin-releasing hormone (TRH) to corticosteroids, given to women at risk of preterm delivery, would decrease the risk of death and severe morbidity associated with prematurity.
                Two concurrent multicentre, double blind, randomised, placebo-controlled trials were designed with a common core dataset to be analysed as a single large pragmatic trial.
                Hospital maternity units.
                Pregnant women at risk of preterm delivery who had been prescribed a course of corticosteroids to enhance fetal maturation.
                Antenatal administration of TRH 400 microg every eight hours for four doses versus matching placebo.
                Primary: death of the baby or chronic lung disease (defined as oxygen dependency at 28 days after birth). Secondary: other measures of respiratory morbidity, in particular respiratory distress syndrome. Other measures of short term neonatal morbidity including intraventricular haemorrhage and necrotising enterocolitis. Measures of maternal side effects.
                The antenatal TRH trial was halted early on the basis of external evidence. Overall a total of 225 women were recruited who delivered 275 babies. The primary outcome of death or chronic lung disease occurred in 33 babies in the TRH group and 43 babies in the placebo group (RR 0.8, 95% CI 0.5-1.2). There were no other differences between the two groups. Stratified analysis did not reveal any differences between the two groups depending on how long before the time of delivery the mother had received the TRH or placebo.
                These trials are too small to provide convincing evidence of the effect of antenatal TRH on neonatal outcome. When added to the existing systematic review and meta-analysis, however, these data should provide evidence on which subsequent practice can be based. The process by which the trials were monitored and stopped is of relevance to future trials.
This review does not support the use of thyroid hormones in preterm infants to reduce neonatal mortality, improve neurodevelopmental outcome or to reduce the severity of respiratory distress syndrome. An analyses of data from one study (van Wassenaer 1997) which showed benefits in infants 24-25 weeks gestation was not prespecified and should be treated with caution. 
The small number of infants included in trials incorporated in this review limits the power of the meta-analysis to detect clinically important differences in neonatal outcomes.
Future trials are warranted and should be of sufficient size to detect clinically important differences in neurodevelopmental outcomes. They should consider enrolling those infants most likely to benefit from thyroid hormone treatment such as infants born at less than 27 weeks gestation.