A randomized, controlled trial of antepartum thyrotropin-releasing hormone and betamethasone in the prevention of respiratory disease in preterm infants

Long-Term Outcomes of 92 Cases of Fetal Hydrothorax Including Thoracoamniotic Shunting

BACKGROUND

There have been no previous reports on the postnatal course, especially long-term outcomes, of fetal hydrothorax patients, including those treated with thoracoamniotic shunting (TAS) using a double-basket catheter.The outcomes of cases from a single center are reported.

METHODS

Cases of fetal hydrothorax managed at our center between 2005 and 2015 were enrolled retrospectively. TAS was performed if indicated. Long-term outcomes such as cerebral palsy, developmental disabilities, and others were analyzed.

RESULTS

Ninety-two cases of fetal hydrothorax were included. The causes were primary chylothorax, transient abnormal myelopoiesis, cardiac disease, pulmonary sequestration, mediastinal neoplasm, and infection. TAS was performed in 36 cases. Early neonatal death occurred in 19 cases. The 28-day survival rates for all cases and for TAS cases were 70% (48/69) and 72% (26/36), respectively. Of the cases that underwent TAS, one was treated with home oxygen therapy, one was diagnosed with cerebral palsy and severe intellectual disability, and five were diagnosed with mild or moderate developmental disabilities.

CONCLUSIONS

The results showed that the survival rate and long-term outcomes of cases with hydrothorax have improved as TAS has become more prevalent. The reasons for these results need to be elucidated, and efforts are needed to further improve outcomes.

Lung development, regeneration and plasticity: From disease physiopathology to drug design using induced pluripotent stem cells

Lungs have a complex structure composed of different cell types that form approximately 17 million airway branches of gas-delivering bronchioles connected to 500 million gas-exchanging alveoli. Airways and alveoli are lined by epithelial cells that display a low rate of turnover at steady-state, but can regenerate the epithelium in response to injuries. Here, we review the key points of lung development, homeostasis and epithelial cell plasticity in response to injury and disease, because this knowledge is required to develop new lung disease treatments. Of note, canonical signaling pathways that are essential for proper lung development during embryogenesis are also involved in the pathophysiology of most chronic airway diseases. Moreover, the perfect control of these interconnected pathways is needed for the successful differentiation of induced pluripotent stem cells (iPSC) into lung cells. Indeed, differentiation of iPSC into airway epithelium and alveoli is based on the use of biomimetics of normal embryonic and fetal lung development. In vitro iPSC-based models of lung diseases can help us to better understand the impaired lung repair capacity and to identify new therapeutic targets and new approaches, such as lung cell therapy.

Timing of cord clamping in very preterm infants: more evidence is needed

In December 2012, the American College of Obstetricians and Gynecologists published a Committee Opinion entitled "Timing of umbilical cord clamping after birth." It stated that "evidence exists to support delayed cord clamping in preterm infants, when feasible. The single most important benefit for preterm infants is the possibility for a nearly 50% reduction in IVH." However, the Committee Opinion added that the ideal timing of umbilical cord clamping has yet to be determined and recommended that large clinical trials be conducted in the most preterm infants. Published randomized controlled trials include <200 infants of <30 weeks' gestation, with assessments of neurodevelopmental outcome in less than one-half of the children. This is a major gap in the evidence. Without reliable data from randomized controlled trials that optimally include childhood follow-up evaluations, we will not know whether delayed cord clamping may do more overall harm than good. Ongoing trials of delayed cord clamping plan to report childhood outcomes in >2000 additional very preterm infants. Current recommendations may need to change when these results become available. Greater international collaboration could accelerate resolution of whether this promising intervention will improve disability-free survival in about 1 million infants who will be born very preterm globally each year.

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.

Molecular mechanisms underlying the fetal programming of adult disease

Adverse events in utero can be critical in determining quality of life and overall health. It is estimated that up to 50 % of metabolic syndrome diseases can be linked to an adverse fetal environment. However, the mechanisms linking impaired fetal development to these adult diseases remain elusive. This review uncovers some of the molecular mechanisms underlying how normal physiology may be impaired in fetal and postnatal life due to maternal insults in pregnancy. By understanding the mechanisms, which include epigenetic, transcriptional, endoplasmic reticulum (ER) stress, and reactive oxygen species (ROS), we also highlight how intervention in fetal and neonatal life may be able to prevent these diseases long-term.

Modeling and Remodeling of the Lung in Neonatal Chronic Lung Disease

Neonatal chronic lung disease (CLD) is the major long-term pulmonary complication of preterm birth affecting about 20% of infants who need mechanical ventilation. CLD is the result of abnormal repair processes following inflammatory lung injury that lead to remodeling of the lung. Inflammation may be initiated by a variety of stimuli including mechanical ventilation, oxygen toxicity and infection. The resultant neutrophil chemotaxis and degranulation leads to the release of enzymes such as matrix metalloproteinases that can cause proteolysis of the lung extracellular matrix. Abnormal healing with remodeling leads to poorly compliant lungs with reduced capacity for gas exchange. Drugs can influence the normal process of lung modeling or remodeling. Fetal lung development can be influenced by glucocorticosteroids and inflammation. Both can cause abnormal lung modeling with fewer, larger alveoli and accelerated lung maturation, which confers benefits in terms of reduced morbidity and mortality from respiratory distress syndrome but potentially increases the risk of subsequent lung injury. Antioxidants, such as retinol (vitamin A), administered post-natally may reduce the effects of oxidative stress leading to a modest reduction in CLD but they require repeated intramuscular injections. Postnatal glucocorticosteroid therapy can modify the lung inflammatory response and reduce CLD but it can also have detrimental effects on the developing brain and lung, thereby creating a clinical dilemma for neonatologists. Proteinase inhibitors may be a rational therapy but more research is needed before they can be accepted as a treatment for preterm neonates.'Modeling' is defined as planning or forming that follows a set pattern. The term is used to describe the normal process of lung growth and development that culminates in mature branching alveolar air spaces surrounded by a network of capillaries. Normal lung modeling occurs under a variety of genetic and hormonal influences that can be altered, leading to abnormal patterns of growth. 'Remodeling' is defined as altering the structure of or re-making and, in the case of the lung, is used to describe the abnormal patterns of lung growth that occur after lung injury. Modeling and remodeling of the lungs occur to an extent throughout life but never more rapidly than during the fetal and early neonatal periods, and factors that influence this process may lead to development of neonatal CLD. Some of the factors involved in normal and abnormal lung modeling and inflammation and glucocorticosteroid-induced remodeling in the perinatal period, in the context of neonatal CLD, are reviewed with considerations of how various drugs may influence these processes.

Effects of betamethasone and thyroid releasing hormone on fetal lung maturation: an experimental and morphometric study

OBJECTIVE

To determine the effects of betamethasone and thyroid releasing hormone (TRH) on morphologic fetal rabbit lung maturation when administered separately and in combination.

MATERIAL AND METHODS

Twenty-five pregnant rabbits were divided into five groups. Study groups were as follows: TRH or betamethasone alone (between 24 and 27th days of gestation), TRH + betamethasone or betamethasone + TRH (second dose of drugs were added in the last 2 days), and the control. The pregnancies were terminated on the 27th day of gestation. Weights and volumes of the fetal lungs were determined and the results were compared.

RESULTS

Mean lung weights in all treatment groups were significantly heavier than controls (P < 0.05). The differences between mean lung weights of TRH alone, TRH + betamethasone, and betamethasone alone groups were not statistically significant (P > 0.05), but the mean lung weight of betamethasone + TRH group was significantly lower than the other treatment groups (P < 0.05). Mean lung volume of TRH alone group was significantly higher than control group; however, there were no significant differences between other treatment groups and the control. No correlation was found between the lung weights and volumes in all groups (r = 0.1, P > 0.05).

CONCLUSION

Only TRH alone treatment produced a significant increase in both fetal lung volume and weight compared to the control group. Administering TRH alone can lead to increased lung maturation. Combining TRH to corticosteroid treatment significantly decreased mean fetal lung weight, instead of an increase. According to these results combined used of these two substances probably counteract each others effect, instead of having a synergism.

Changing trends in the management of respiratory distress syndrome (RDS)

The management of respiratory distress syndrome (RDS) has advanced because of improvements in mechanical ventilators, promotion of antenatal steroids, availability of surfactant and overall advancements in neonatal intensive care. Intermittent mandatory ventilation still forms the mainstay of assisted ventilation. Newer modes of ventilation have not delivered the results as promised. Because of the continued high incidence of bronchopulmonary dysplasia, there is a renewed interest in non-invasive modes of ventilation like CPAP and nasal IPPV. The present trend is to follow gentle ventilatory strategies accepting higher arterial carbon dioxide and lower oxygen. The role of antenatal steroids has been established beyond doubt but still they fall short of universal acceptance. Surfactant replacement therapy is the standard of care for RDS but beyond the reach of majority in India. Postnatal steroids are out of vogue because of probable links with cerebral palsy and abnormal neurological outcomes.

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.

Therapies administered to mothers at risk for preterm birth and neurodevelopmental outcome in their infants

A decrease in the rate of preterm births and the prevention of prematurity-associated neurodevelopmental morbidity are critical for the reduction of neurodevelopmental disability. Efforts to reduce the overall preterm delivery rate have been unsuccessful. Although progress has been achieved in the prevention of short-term neonatal morbidity over the past several decades, the majority of the improvements have resulted from improved neonatal care. Whether obstetric interventions can improve neurodevelopmental outcome is unknown. The ability to adequately assess obstetric interventions is hampered by the limited number of interventional studies that included long-term outcome assessment. Thus, it is incumbent upon ongoing and future interventional studies to consider long-term outcome assessment as a critical component of the overall evaluation of efficacy of obstetric therapies.

Neurodevelopmental outcome of children treated with antenatal thyrotropin-releasing hormone

OBJECTIVE

To evaluate neurodevelopmental outcome until 2 years of age in children who participated in a multicenter antenatal thyrotropin-releasing hormone (TRH) trial to improve respiratory outcome and to lower mortality.

METHODS

Neurodevelopmental outcome was studied in infants whose mothers were admitted to the Academic Medical Center and enrolled in the European Antenatal TRH trial. Mothers were treated for imminent preterm delivery (before 30 weeks) with corticosteroids plus either placebo (placebo-group) or TRH (TRH-group). TRH treatment consisted of 400 micro g every 8 hours up to 4 doses. Assessments included neurologic development at 12 months and psychomotor development at 12 and 24 months using the Bayley developmental scales.

RESULTS

Sixty-two infants were included, 10 of whom died. Of the surviving infants, 24 received TRH and 28 received placebo. Ten infants were lost to follow-up. Each group consisted of 21 infants. Both groups were comparable regarding gestational age, birth weight, and time interval between trial medication and birth. However, in the TRH group, more respiratory problems, ventilator days, and chronic lung disease were found. Neurologic and motor outcome did not differ between the groups, but lower mental developmental index scores were found in the TRH group at both ages.

CONCLUSIONS

Antenatal TRH treatment is associated with a delay in mental development. This study demonstrates the importance of long-term follow-up of perinatal intervention trials with possible consequences for neurodevelopmental outcome of the infant.

Is there a role for antenatal TRH therapy for the prevention of neonatal lung disease?

Unfortunately, surfactant therapy is not routinely available to infants in some parts of the world because of its cost. It is the hypothesis of this article that in situations where surfactant is not available, there may be a role for antenatal thyrotropin-releasing hormone (TRH) plus glucocorticoid therapy. Data from randomized clinical trials, which compared therapy with antenatal glucocorticoid plus TRH to that with glucocorticoid alone were extracted and subjected to meta-analysis. The trials that incorporated surfactant therapy were analyzed separately from those in which surfactant was not used. In addition, because surfactant therapy was only available to some patients in the Australian ACTOBAT trial, each group analysis was performed with and without the ACTOBAT data. A characteristic of the earlier presurfactant trials is that few were designed for "intention to treat" analysis. In most of these studies, it was decided a priori to include babies who delivered within a specified time period after hormone therapy. The addition of TRH did not decrease respiratory distress syndrome in those trials in which surfactant therapy was used. In the presurfactant trials, respiratory distress syndrome was significantly decreased when "intention to treat" data were examined, as well as in those infants who delivered between 1 and 10 days after maternal therapy. There was also a significant decrease in oxygen dependency at 28 days after birth, and in oxygen dependency or death at this time, in those infants who delivered 1 to 10 days after treatment. Antenatal TRH had no significant effect of on neonatal complications such as air leak, intraventricular hemmorhage, patent ductus arteriosus, retinopathy of prematurity, or necrotizing enterocolitis. However, TRH did produce transient suppression of the pituitary thyroid axis. There were also a variety of transient complications in the mothers, including nausea, vomiting or flushing, light-headed feeling, and increased blood pressure. The authors conclude that the implementation of appropriate antenatal glucocorticoid treatment is the first priority. Once this has been established, the data presented here suggest that addition of antenatal TRH should be considered in those situations where surfactant is not available.

The controversy of the treatment of critically ill patients with thyroid hormone

There is currently a vast literature available on the changes in thyroid function tests that occur during non-thyroidal illness. The aetiology of these changes is, however, controversial, especially with respect to whether they play an adaptive role for the organism in order to cope with stress or whether they represent primary pathology of the pituitary-thyroid axis. This is particularly true for critically ill patients, in whom the most significant changes in thyroid function are observed. The changes include low levels of thyroxine and very low levels of tri-iodothyronine, which would, on the surface, appear to indicate hypothyroidism. Therapy with thyroid hormone, as either L-T4 or L-T3, has therefore been suggested because of these low values for thyroid hormones in the blood. It is, however, unclear whether treating these patients with thyroid hormone is beneficial or harmful. Multiple studies have addressed this issue with patients with cardiac disease, sepsis, pulmonary disease (e.g. acute respiratory distress syndrome) or severe infection, or with burn and trauma patients. In spite of a very large number of published studies, it is very difficult to form clear recommendations for treatment with thyroid hormone in the intensive care unit. Instead, we find the evidence far from compelling, and would advise withholding thyroid hormone therapy in the critical care setting in the absence of clear clinical or laboratory evidence for hypothyroidism.

A prospective, randomized trial comparing the efficacy of dexamethasone and betamethasone for the treatment of antepartum HELLP (hemolysis, elevated liver enzymes, and low platelet count) syndrome

OBJECTIVE

This study was undertaken to determine whether dexamethasone or betamethasone is superior for the antepartum treatment of HELLP (hemolysis, elevated liver enzymes, and low platelet count) syndrome.

STUDY DESIGN

This prospective, randomized, clinical investigation compared intravenously administered dexamethasone and intramuscularly administered betamethasone in the treatment of gravid women with HELLP syndrome. Efficacy end points included laboratory values (platelet count, lactate dehydrogenase activity, aspartate aminotransferase activity) and clinical parameters (mean arterial pressure, urinary output).

RESULTS

Forty patients were enrolled in the study, 19 in the dexamethasone arm and 21 in the betamethasone arm. The adjusted time-averaged changes from baseline were significant for aspartate aminotransferase activity (dexamethasone, -20.4 +/- 9.6 U/L; betamethasone, 9.9 +/- 8.9 U/L; P =.029), mean arterial pressure (dexamethasone, -15.6 +/- 1.4 mm Hg; betamethasone, -8.1 +/- 1.4 mm Hg; P <.001), and urinary output (dexamethasone, 12.9 +/- 8.6 mL/h; betamethasone, -11.9 +/- 8.2 mL/h; P =.043).

CONCLUSION

Intravenously administered dexamethasone appears to be more effective than intramuscularly administered betamethasone for the antepartum treatment of mothers with HELLP syndrome.

Strategies for prevention of neonatal chronic lung disease

Chronic lung disease (CLD) of prematurity remains a substantial problem despite modern perinatal and neonatal care. CLD remains related to gestational age and lung immaturity, although it has become clear that severe initial lung disease is not a prerequisite for CLD to develop. Attempts to prevent CLD to date have not adequately addressed the multifactorial nature of the complex pathophysiology that leads to CLD. Thus, results have been modest at best. Prevention of CLD will require a multifaceted approach with specific interventions and care practices focused on different aspects of the pathway that leads to CLD. This review considers new information related to causation of CLD and the magnitude of the effect of prevention strategies tested to date. This article also advances the hypothesis that CLD is preventable with a global strategy of minimizing inciting events, optimizing management, and specific therapies aimed at intrinsic vulnerabilities.

Prenatal thyrotropin-releasing hormone for preterm birth

BACKGROUND

Adding thyrotropin-releasing hormones (TRH) to corticosteroids has been suggested as a way of improving fetal lung development.

OBJECTIVES

The objective of this review was 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, Cochrane Controlled Trials Register, and bibliographies. Date of last search: January 1999.

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 neonatal mortality, neonatal 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 4500 women were recruited into the 11 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, chronic oxygen dependance, or improve fetal, neonatal or childhood outcome in any of the 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 infants needing ventilation (relative risk (RR) 1.16, 95% confidence interval (CI) 1.03-1.29), having a low Apgar score at five minutes (RR 1.80, 95% CI 1.14-1.92) and, for the one trial providing data, was associated with poorer outcomes at the 12 month follow up. Sensitivity analyses by trial quality, or subgroups with differing times from entry to delivery, or different dose regimens of TRH, did not change these findings.

REVIEWER'S CONCLUSIONS

On the basis of currently available evidence, prenatal TRH, in addition to corticosteroids, given to women at risk of very preterm birth cannot be recommended for clinical practice.

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.

Plasma thyroid hormones in premature infants: effect of gestational age and antenatal thyrotropin-releasing hormone treatment. TRH Collaborative Trial Participants

Thyroid hormones are important for both perinatal adaptation and long-term psychomotor development; however, there is limited information on the effects of extreme prematurity and antenatal TSH-releasing hormone (TRH) treatment on pituitary-thyroid function. In this study we assayed plasma triiodothyronine (T3) and TSH in infants who were part of a collaborative trial of antenatal maternal TRH therapy. Within the control population (n = 166), infants of 24-28-wk and 28-32-wk gestational age had comparable levels of T3 (0.94 and 1.06 nmol/L, respectively) and TSH (5.7 and 7.2 mU/L) at birth, but the increases at 2 h and subsequent T3 levels were less in the 24-28 wk versus 28-32-wk gestation infants. In the TRH-treated group (n = 131), T3 was lower in the first day for infants delivered 7-72 h after antenatal TRH compared with control infants. TSH at birth was approximately 3.5-fold greater for infants delivered at 0-6 h after the last TRH dose compared with the control group and was suppressed in infants delivering at 7-36 h. T3 and TSH levels were not different between control and TRH-treated groups at 3-28 d of age. In TRH stimulation tests on d 28, control and TRH-treated groups had similar peak levels of TSH and incidence of exaggerated response (TSH > or = 35 mU/L). We conclude that extremely premature infants have a reduced postnatal surge in TSH and T3 and maintain lower T3 concentrations, probably reflecting tertiary hypothyroidism. The stimulatory and suppressive effects of antenatal TRH treatment observed at birth are transient and do not affect pituitary-thyroid responsiveness at 28 d of age.

Differential effects in vivo of thyroid hormone on the expression of surfactant phospholipid, surfactant protein mRNA and antioxidant enzyme mRNA in fetal rat lung

Antenatal administration of triiodo-L-thyronine (T3) to late gestation rats resulted in decreased lung antioxidant enzyme (AOE) activity but increased surfactant phospholipids. In fetal rat lung explant cultures, T3 decreased the expression of surfactant proteins (SP) A and B. There have been no reported studies of the simultaneous in vivo developmental influence of T3 on both pulmonary AOE and SP gene expression. We hypothesized that antenatal T3 treatment would cause differential regulation of surfactant phospholipid, SP, and AOE genes in the late gestation fetal rat. Timed pregnant rats received intramuscular injections of either T3 (7 mg/kg) or placebo on days 19 and 20 of gestation and fetuses were delivered on day 21. Fetal lung SP-A, SP-B, SP-C, and AOE mRNA levels were studied by Northern analysis. AOE mRNA levels were further quantitated by solution hybridization. Total lung phospholipids (TPL) and disaturated phosphatidylcholine (DSPC) content were quantitated by a phosphorus assay. T3 significantly increased TPL and DSPC content, and significantly decreased the expression of SP-A, SP-C, CuZnSOD, and catalase genes. Because of a crucial interplay of these factors for normal lung function at the time of birth, the molecular mechanisms by which these apparently opposing changes are accomplished warrant further investigation.

Ambulatory management of multiple gestation

Ambulatory management of multiple gestation requires careful and continuing care by the obstetrician. The initial evaluation should include a comprehensive history, including use of fertility enhancing drugs and ART, family history, social history; a general physical examination, including a pelvic examination; laboratory evaluation, including complete blood cell count, dipstick urinalysis for protein and glucose, urine culture, blood type, Rh factor and irregular blood antibody determination, serology for rubella, syphilis, hepatitis B surface antigen and varicella (if there is no history). A Papanicolaou smear should be done at the time of the pelvic examination, as should evaluation for bacterial vaginosis. Ultrasound assessment of placentation should be done at 14 weeks' gestation, but vaginal or perineal ultrasound of cervical length should be done at the initial visit. Other testing procedures should include repeat ultrasound evaluation for fetal growth every 4 weeks in a dichorionic placentation and every 3 weeks if monochorionic placentation is present. Triple screen MSAFP at 16-18 weeks' gestation and blood sugar screening at 22-26 weeks should be performed. After the first trimester, the patient should schedule physician visits every 2 weeks or less. Routine medications should include one prenatal vitamin per day, additional folic acid supplementation of 1.0 mg per fetus, supplemental iron preparation, and additional calcium to equal 1500 mg/day. The use of low-dose aspirin to prevent preeclampsia in twin gestations has not been adequately studied. Continuing vigilance by the knowledgeable obstetrician should occur. Multiple gestations should not be cared for by non-physician providers or by family physicians. Referral to a maternal-fetal medicine unit is recommended.

Antenatal thyrotropin-releasing hormone to prevent lung disease in preterm infants. North American Thyrotropin-Releasing Hormone Study Group

BACKGROUND

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.

METHODS

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.

RESULTS

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.

CONCLUSIONS

In preterm infants at risk for lung disease, antenatal administration of thyrotropin-releasing hormone and glucocorticoid is no more beneficial than glucocorticoid alone.

Collaborative trial of prenatal thyrotropin-releasing hormone and corticosteroids for prevention of respiratory distress syndrome. Collaborative Santiago Surfactant Group

OBJECTIVE

Our purpose was to determine whether adding antenatal thyrotropin-releasing hormone to prenatal corticosteroids reduces the frequency of respiratory distress syndrome.

STUDY DESIGN

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.

RESULTS

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]).

CONCLUSIONS

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.

Thyrotropin-releasing hormone accelerates fetal mouse lung ultrastructural maturation via stimulation of extra thyroidal pathway

Maternal administration of TSH-releasing hormone (TRH) in the euthyroid mouse accelerates fetal lung ultrastructural maturation. However, the mechanism(s) of TRH in fetal lung development remains unclear; it could be due to its neuroendocrine and/or neurotransmitter effects. Although the neuroendocrine effect of TRH is mediated via stimulation of the fetal pituitary-thyroid axis, the neurotransmitter effect is mediated via stimulation of fetal autonomic nervous system activity. In the hyt/hyt mouse there is a point mutation in the beta subunit of the TSH receptor in the thyroid gland of the Balb-c mouse. In these mice TSH does not bind to its receptors, leading ultimately to the development of primary hypothyroidism, which is transmitted as an autosomal recessive trait. A maturational delay in the lung ultrastructure of the hyt/hyt mouse fetus has been observed. This investigation was undertaken to study the effect of maternal TRH treatment on lung ultrastructural maturation in the hyt/hyt mouse fetus. If the effect of TRH is mediated via stimulation of fetal pituitary-thyroid axis, TRH treatment should not enhance lung maturity in the hyt/hyt fetus and vice versa. Adult hyt/hyt mice made euthyroid by triiodothyronine supplementation were mated to carry hyt/hyt pups. Saline or TRH (0.4 or 0.6 mg/kg/dose) was administered to the mother (i.p.) on d 16 and 17 (b.i.d.) and on d 18 of pregnancy 1 h before killing (term, approximately 20 d). The fetal lung electron micrographs were subjected to ultrastructural morphometric analysis of the number of lamellar bodies and glycogen/nuclear ratio in type II cells, and the alveolar/parenchymal ratio by Chalkley point counting with an interactive computerized image analyzer (Optimas, Bioscan). Fetal lungs exposed to the lower dose of TRH (n = 7) showed no significant difference in their ultrastructural maturation when compared with saline-treated controls (n = 5). However, fetal lungs exposed to a higher dose of TRH (n = 6) showed increased numbers of lamellar bodies per type II cell, an increase in the alveolar/parenchymal ratio, larger air spaces, thinner alveolar septa, presence of tubular myelin, and increased numbers of air-blood barriers. We conclude that the effect of TRH in accelerating fetal mouse lung maturation is at least in part mediated via stimulation of extra thyroidal pathways.

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

OBJECTIVE

The goal was to study the effects on uterine contractility, blood pressure, and heart rate of thyrotropin-releasing hormone given antenatally in combination with glucocorticoids to accelerate fetal maturation.

STUDY DESIGN

A placebo-controlled, randomized, double-blind study was performed involving 30 women whose pregnancies were followed up at the University Hospital Gasthuisberg in 1994 and 1995.

RESULTS

Thyrotropin-releasing hormone induced a significant mean increase of nearly 6 mm Hg in systolic blood pressure and approximately 5 mm Hg in diastolic blood pressure. The duration of this raise was < 20 minutes. Thyrotropin-releasing hormone had no significant effect on maternal heart rate or uterine contractility: 4.2 +/- 1.6 contractions per hour before versus 4.7 +/- 1.7 contractions per hour after treatment.

CONCLUSIONS

Thyrotropin-releasing hormone induces a small (mean < 6 mm Hg) and brief mean (< 20 minutes) increase in blood pressure but appears to have no clinically detectable effect on uterine contractility.

Prenatal glucocorticoid and T4 effects on lung morphology in preterm lambs

Prenatal glucocorticoid plus T4 treatment of fetal sheep results in improvements in oxygenation, gas exchange, lung mechanics, and lung volumes after preterm delivery. We have evaluated the morphometric changes in the lungs of lambs exposed to betamethasone and T4 48 h before preterm delivery at 121 and 135 d gestation and related those changes to the physiologic improvements in lung function. The lungs used for the morphometric studies were from lambs with postnatal physiologic responses similar to those of the entire group of lambs reported previously (16). At both 121 and 135 d gestation, lung gas volumes and fixed tissue volumes increased, the percent of collapsed (nonaerated) parenchyma decreased, and the percent of perilobular connective tissue decreased with both gestational age and prenatal hormone exposure. Alveolar size, as estimated by mean linear intercept length, did not change with gestation or hormone exposure, but there was a decrease in alveolar wall thickness with advancing gestation and at each gestation with hormone exposure. The major anatomic effect of prenatal hormone exposure was a decrease in alveolar wall thickness and an increase in aerated parenchyma, effects that were consistent with the physiologic improvements in postnatal lung function.

Maternofetal transfer of thyrotrophin-releasing hormone: effect of concentration and mode of administration

We studied the effect of maternal concentration and mode of administration on transfer rate of TSH-releasing hormone (TRH) in an in vitro model of dually perfused isolated lobule of human term placenta. Varying concentrations (4-40 microg dL(-1)) of TRH were added either to the open maternal circulation to mimic an infusion or as a single bolus dose to the closed maternal circulation. TRH was measured by RIA. Perfusion efficiency in each experiment was determined by using antipyrine and creatinine as diffusable markers. At a concentration equivalent to the usual clinical dose of 400 microg, transplacental transfer of TRH was 0.4 +/- 0.1%, with an fetal/maternal ratio of 0.01 +/- 0.003. Placental clearance rate (y = 0.07x; R2 = 0.97; p < 0.001; n = 28) and uptake of TRH (y = 0.40x; R2 = 0.95; p < 0.001) in the closed experiments increased exponentially with increasing maternal concentration. Placental clearance (y = 0.05x; R2 = 0.99; p < 0.001; n = 30), and uptake of TRH (y = 0.35x; R2 = 0.98; p < 0.01) under steady state also correlated with maternal TRH concentration. For a given concentration, placental clearance and uptake of TRH was comparable whether given as a bolus or an infusion. We conclude that TRH is transferred sparingly across the human term placenta and its transfer rate is a function of the maternal concentration of TRH and not its mode of administration.

Australian Collaborative Trial of Antenatal Thyrotropin-Releasing Hormone: adverse effects at 12-month follow-up. ACTOBAT Study Group

OBJECTIVE

The Australian Collaborative Trial of Antenatal Thyrotropin-Releasing Hormone (ACTOBAT) assessed the efficacy of 200 microg of thyrotropin-releasing hormone (TRH) in combination with glucocorticoids in the prevention of neonatal lung disease. This paper reports the 12-month follow-up of the infants from the trial completed in 1994.

DESIGN

This was a double-blinded randomized controlled trial.

SETTING

Women were recruited from level 3 perinatal centers throughout Australia.

PARTICIPANTS

Mothers who had not withdrawn from treatment and whose infants were discharged alive (1262 infants). Extensive efforts were made to trace this entire cohort.

OUTCOME MEASURES

A questionnaire was mailed to parents for self-completion immediately before their baby's/babies' first birthday. The questionnaire included a checklist to assess sensory, motor, language, and social development, and use of health services.

RESULTS

Milestone scores were developed from items on the follow-up form. Treatment with TRH was associated with an increased risk of motor delay, social delay, fine motor delay, sensory impairment, and early language impairment. No differences were seen between treatment and placebo groups for motor impairment. Multivariate analyses were performed, adjusting for chronological age, duration of gestation at randomization, time from randomization to delivery, parity, history of perinatal death, history of preterm rupture of the membranes, infant sex, singleton or twin status, maternal age, and maternal blood pressure (systolic and diastolic) at randomization. For the total cohort (N = 1022), treatment with TRH was associated with motor delay (odds ratio [OR], 1.51; 95% confidence interval [CI] 1.11 to 2.05); social delay (OR 1.40; 95% CI 1.01 to 1.95); sensory impairment (OR, 2.00; 95% CI 1.06 to 3.74); severe impairment (OR, 1.75; 95% CI 1.07 to 2.87); and a trend toward motor impairment (OR, 1.50; 95% CI .97 to 2.33), early language impairment (OR, 1.27, 95% CI .90 to 1.79), and fine motor delay (OR, 1.15; 95% CI .83 to 1.60). There were no differences between the treatment groups in hospital admissions (OR, 1.08; 95% CI .83 to 1.42), doctors' visits (general practitioner OR adj, 1.09; 95% CI .79 to 1.50 or specialist OR adj 1.15; 95% CI .87 to 1.49), respiratory symptoms (OR adj, 1.16; 95% CI .88 to 1.53), or behavioral disturbances (OR adj, .93; 95% CI .71 to 1.21).

CONCLUSIONS

Because antenatal administration of TRH is associated with small, consistent deficits in major milestone achievements at 12 months of age, it is essential that additional planned trials make provision for long-term follow-up. Antenatal TRH should only be used in the context of a clinical trial.

Fetal drug therapy

As prenatal diagnosis has become more sophisticated, avenues for a variety of intrauterine therapies have been opened. Considerable experience has been gained with surgical and pharmacologic approaches. This article provides a review of intrauterine drug therapy aimed at preventing fetal and neonatal disease and treating existing fetal conditions. The future awaits the exciting applications of intrauterine hematopoietic transplants and genetic therapy.

Correlates of low thyroxine values at newborn screening among infants born before 32 weeks gestation

We assessed the relation of perinatal factors to severe hypothyroxinemia of prematurity, defined as thyroxine value more than 2.6 standard deviations below the mean for newborns. The 365 survivors of birth before 32 weeks gestation were enrolled in a population-based study of the correlates of neonatal brain injury. In this historical cohort study, mothers were interviewed; perinatal data were abstracted from medical records and neonatal data were collected prospectively. Neonatal thyroxine screening values were retrieved from the New Jersey State Department of Health. Associated with severe hypothyroxinemia were: gestational age 23-27 weeks vs. 31 weeks (OR = 5.1, 95% CI 1.7, 15.2), later age at thyroxine test (OR = 1.6 per day, 95% CI 1.2, 2.1), fraction inspired oxygen at age 24 h > 40% (OR = 3.2, 95% CI 1.1, 8.8), mechanical ventilation (OR = 5.1, 95% CI 1.3, 19.4), diastolic blood pressure < 20 mmHg (OR = 2.3, 95% CI 1.2, 4.3), and > 12 years of maternal education (OR = 0.4, 95% CI 0.22, 1.0). Infants with severe hypothyroxinemia had higher mortality, more days of oxygen supplementation, ventilation and hospitalization and were 11 times more likely to require oxygen supplementation at the postnatal age equivalent to 36 weeks gestational age (odds ratio 10.6, 95% CI 2.3, 48.8). In preterm infants, neonatal thyroxine levels obtained at newborn screening in the first week of life may convey important prognostic information about mortality, morbidity, and the risk for bronchopulmonary dysplasia.

Effect of absent end diastolic flow velocity in the fetal umbilical artery on subsequent outcome

Sixty babies, delivered over a six and a half year period, who had absent end diastolic frequency (AEDF) in the umbilical artery, were studied. Individually matched control pregnancies for gestational age, birth-weight, maternal clinical condition and date of delivery, in whom umbilical artery recordings showed end diastolic frequency, were also studied. Matching was achieved in 36 cases. Neonates from case pregnancies showed no increase in necrotising enterocolitis, intraventricular haemorrhage, pneumothorax, neonatal death or bronchopulmonary dysplasia. However, they were significantly less likely to require ventilation for respiratory distress syndrome (P = 0.02). Although AEDF indicates a fetus under vascular stress, this finding alone will include a spectrum of response in the baby, from the well compensated to the irreversibly damaged. Delivery at different points in the deteriorating fetal environment may explain discrepant study results. This intrauterine stress, by increasing fetal corticosteroid and thyroid hormones, may account for enhanced lung maturity. Predictions of neonatal course need to be based on more comprehensive awareness of fetal status.

[Prenatal corticotherapy and acceleration of fetal maturation. II. Results of clinical applications]

Numerous subsequent controlled trials and recent meta-analysis have confirmed the efficiency of antenatal glucocorticoid therapy in reducing both the incidence of respiratory distress syndrome (RDS) and perinatal mortality. Moreover, antenatal glucocorticoid administration reduces the odds of several severe complications relating to immaturity: intraventricular hemorrhage (IVH), ductus arteriosus patency, necrotising enterocolitis, and hemodynamic failure. Exogenous surfactant therapy has not ruled out the benefits of corticosteroids: on the contrary, a synergic effect is obtained when both antenatal and postnatal therapeutic approaches are combined. Very premature infants may also take advantage of the hormonal treatment: in this population, RDS occurrence, IVH incidence and perinatal mortality are also reduced. Unfortunately, despite convincing evidence, the incidence of antenatal steroids therapy has not yet achieved the optimal and desirable level. Obstetricians and pediatricians must be encouraged to ensure high maternal exposure to steroids when preterm delivery is likely to occur.

Antenatal steroids: miracle drug for preemies

Antenatal corticosteroid administration has been unequivocally demonstrated to reduce neonatal morbidity and mortality. In addition to its well-documented role in reducing respiratory distress syndrome, evidence is accumulating indicating the global maturational effect of this therapy in the growing fetus. New data demonstrates, the hitherto relatively not well known, beneficial effects of this mode of therapy on renal, cardiovascular, gastrointestinal, endocrinal and cerebral maturation. Despite its well proven efficacy and safety, this therapy is used only in a small fraction of eligible mothers. In this article, biological basis of antenatal steroids use, clinical benefits including those to extremely premature infants, indications for their administration, treatment regimens, practice variations in their administration, cost analysis, and some directions for future research are reviewed. It is hoped that given the evidence reviewed in this article, the use of antenatal steroids administration in proper clinical settings will increase with a significant impact in reducing the neonatal morbidity and mortality.

Thyrotropin-releasing hormone: does two hundred micrograms provide effective stimulation to the preterm fetal pituitary gland compared with four hundred micrograms?

OBJECTIVE

Our purpose was to compare the response of the fetal pituitary-thyroid axis to 200 and 400 micrograms of thyrotropin-releasing hormone administered to the mother immediately before delivery with a control group.

STUDY DESIGN

A randomized controlled trial was conducted of 26 women at gestational ages between 24 weeks and 33 weeks 6 days who had received one or more doses of betamethasone who were expected to be delivered within 1 to 4 hours. Women received either 200 or 400 micrograms of thyrotropin-releasing hormone or were in the control group.

RESULTS

Thyroid-stimulating hormone determinations on cord blood had a higher mean level in both treatment groups compared with the control group. No differences were seen in cord blood results between the two treatment groups for thyroid-stimulating hormone, thyroxine, triiodothyronine, free thyroxine, free triiodothyronine, and prolactin levels. The only other differences found were in a higher level in total thyroxine and a lower level of free thyroxine in the 400 micrograms thyrotropin-releasing hormone group compared with the 200 micrograms group in the 48-hour blood determinations.

CONCLUSION

Both 200 and 400 micrograms of thyrotropin-releasing hormone provided fetal pituitary stimulation, as reflected in fetal thyroid-stimulating hormone levels in cord blood, and both gave significantly higher levels compared with a control group.

Respiratory distress syndrome of the newborn infant

Pulmonary immaturity, including deficiency in the surfactant system, incomplete structural/functional development of lungs and high chest wall compliance contribute to the pathogenesis of respiratory distress syndrome (RDS). Pulmonary edema and overperfusion, resulting from a patent ductus arteriosus, may further worsen the respiratory failure, and aggravate the surfactant deficiency. Infants born prematurely present with respiratory distress within the first few minutes of life. This quickly becomes life-threatening, and may result in death from severe respiratory failure if appropriate respiratory and general supportive therapy are not immediately instituted. The oxygenation deficit in RDS is secondary to V/Q mismatch and right-left shunting of blood via pulmonary and extrapulmonary routes. Hypoxemia induced pulmonary vasoconstriction further contributes to V/Q mismatch and R-L shunting. Hypoventilation in RDS is due to decreased tidal volume, increased dead space ventilation, and finally, decreased minute ventilation. Characteristically, pulmonary compliance, both static and dynamic, are greatly reduced resulting in a high work of breathing, whereas airway resistance is normal or only slightly increased. This combination of abnormal pulmonary mechanics results in lower respiratory time constant in respiratory units, and helps in achieving ventilation and oxygenation by using low inspiratory time in the ventilator. Management of RDS starts with prenatal identification of the risk, prolongation of pregnancy by tocolysis and prenatal administration of pharmacological agents, like betamethasone. These agents increase the pulmonary gas exchange surface area and induce endogenous pulmonary surfactant in the fetus. Advances in ventilatory and general management techniques have strikingly improved the outcome and prognosis of children suffering from RDS since the 1960s. Recent advancements in the prevention and treatment of RDS, e.g., acceleration of lung development by prenatal pharmacological manipulations and postnatal provision of exogenous surfactant, have significantly contributed to the decrease in mortality from RDS. Pharmacological induction of lung maturation by drugs in combination, and improved technology in lung ventilation are expected to further improve the course and outcome of the disease in future.

Antenatal lung maturation--should we all be using thyrotropin-releasing hormone?

Thyrotropin-releasing hormone (TRH) appears to be a promising antenatal therapy to help reduce neonatal lung disease. Clinical trials, however, show differing results. At present the optimum dosage, frequency and method of administration have not been established. TRH has been shown significantly to elevate blood pressure in patients with preeclampsia suggesting it should not be used in this group. Moreover concerns over its use in growth retarded fetuses and its long-term neonatal effects have not been addressed. Further trials are needed before routine clinical use can be recommended.