Effect of antenatal thyrotropin-releasing hormone on uterine contractility, blood pressure, and maternal heart rate

Thyrotropin-releasing hormone added to corticosteroids for women at risk of preterm birth for preventing neonatal respiratory disease

BACKGROUND

Thyrotropin-releasing hormones (TRH) added to prenatal corticosteroids has been suggested as a way to further reduce breathing problems and neonatal lung disease in infants born preterm.

OBJECTIVES

To assess the effects of giving prenatal TRH in addition to corticosteroids to women at risk of preterm birth for the prevention of neonatal respiratory disease.

SEARCH METHODS

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (30 June 2013) and reference lists of retrieved studies. We also contacted trial authors.

SELECTION CRITERIA

Randomised controlled trials in women at sufficient risk of preterm birth to warrant the use of prenatal corticosteroids to promote lung maturity. TRH and corticosteroids were compared with corticosteroids, with or without placebo.

DATA COLLECTION AND ANALYSIS

All assessments of trial eligibility, risk of bias and data extractions were independently carried out by at least two review authors.

MAIN RESULTS

Over 4600 women were recruited into the 15 trials included in the review, however two trials did not contribute any outcome data to the review. The trials had a moderate risk of bias. Overall, prenatal TRH, in addition to corticosteroids, did not reduce the risk of death prior to hospital discharge (risk ratio (RR) 1.05, 95% confidence interval (CI) 0.86 to 1.27, six trials, 3694 infants), neonatal respiratory distress syndrome (average RR 1.05, 95% CI 0.91 to 1.22, nine trials, 3833 infants), or chronic lung disease (RR 1.01, 95% CI 0.85 to 1.19, five trials, 2511 infants), and did not improve any of the secondary fetal, neonatal or childhood outcomes assessed by intention-to-treat analyses.Indeed, the data showed prenatal TRH to have adverse effects for women and their infants. All side effects reported (nausea, vomiting, light headedness, urgency of micturition, facial flushing) were significantly more likely to occur in women receiving TRH. In the infants, prenatal TRH increased the risk of needing respiratory support (RR 1.16, 95% CI 1.03 to 1.29, three trials, 1969 infants), and of having a low Apgar score at five minutes (RR 1.48, 95% CI 1.14 to 1.92, three trials, 1969 infants). Only three trials provided data on childhood follow-up, and while one trial suggested poorer outcomes for infants who were exposed to prenatal TRH, the other two trials, that assessed infants using an established developmental instrument, showed no clear differences between groups in follow-up outcomes.Sensitivity analyses by trial quality, or subgroups with differing times from entry to birth, or different dose regimens of TRH, did not change these findings.

AUTHORS' CONCLUSIONS

Prenatal TRH in addition to corticosteroids, given to women at risk of preterm birth, does not improve infant outcomes and can cause maternal side effects.

Thyrotropin-releasing hormone added to corticosteroids for women at risk of preterm birth for preventing neonatal respiratory disease

BACKGROUND

Thyrotropin-releasing hormones (TRH) added to prenatal corticosteroids has been suggested as a way to further reduce breathing problems and neonatal lung disease in infants born preterm.

OBJECTIVES

To assess the effect of giving prenatal TRH in addition to corticosteroids to women at risk of very preterm birth for the prevention of neonatal respiratory disease.

SEARCH STRATEGY

We searched the Cochrane Pregnancy and Childbirth Group trials register (July 2003), the Cochrane Central Register of Controlled Trials (The Cochrane Library, Issue 3, 2003), MEDLINE (1965 to July 2003), EMBASE (1988 to July 2003), Current Contents (1997 to July 2003).

SELECTION CRITERIA

Randomised controlled trials in women at sufficient risk of preterm birth to warrant the use of prenatal corticosteroids to promote lung maturity. TRH and corticosteroids were compared with corticosteroids with or without placebo. The main outcomes considered were fetal and infant mortality, infant morbidity, childhood development and maternal morbidity.

DATA COLLECTION AND ANALYSIS

All assessments of trial eligibility, quality and data extractions were done by at least two authors independently.

MAIN RESULTS

Over 4600 women were recruited into the 13 included trials. Five trials were rated of high quality. Overall, prenatal TRH, in addition to corticosteroids, did not reduce the risk of neonatal respiratory disease or chronic oxygen dependence, and did not improve any of the fetal, neonatal or childhood outcomes assessed by intention to treat analyses.Indeed, the data showed prenatal TRH to have adverse effects for women and their infants. All side-effects monitored were more likely to occur in women receiving TRH. In the infants, prenatal TRH increased the risk of needing ventilation (relative risk (RR) 1.16, 95% confidence interval (CI) 1.03 to 1.29, 3 trials, 1969 infants), having a low Apgar score at five minutes (RR 1.48, 95% CI 1.14 to 1.92, 3 trials, 1969 infants) and, for the two trials providing data, was associated with poorer outcomes at childhood follow up. Sensitivity analyses by trial quality, or subgroups with differing times from entry to birth, or different dose regimens of TRH, did not change these findings.

REVIEWERS' CONCLUSIONS

Prenatal thyrotropin-releasing hormones, in addition to corticosteroids, given to women at risk of very preterm birth do not improve infant outcomes and can cause maternal side-effects.

Two trials of antenatal thyrotrophin-releasing hormone for fetal maturation: stopping before the due date. Antenatal TRH Trial and the Thyroneth Trial Groups

OBJECTIVES

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.

DESIGN

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.

SETTING

Hospital maternity units.

POPULATIONS

Pregnant women at risk of preterm delivery who had been prescribed a course of corticosteroids to enhance fetal maturation.

INTERVENTIONS

Antenatal administration of TRH 400 microg every eight hours for four doses versus matching placebo.

MAIN OUTCOME MEASURES

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.

RESULTS

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.

CONCLUSIONS

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.