Does implementing a regime of dexamethasone before planned cesarean section at term reduce admission with respiratory morbidity to neonatal intensive care unit? A randomized controlled trial

PRECeDe Pilot: Prevention of neonatal respiratory distress with antenatal corticosteroids before elective caesarean section in women with diabetes - a feasibility randomised trial

OBJECTIVE

The PRECeDe Pilot Trial was designed to determine the feasibility of undertaking a multicentre, randomised controlled trial (RCT) to assess the efficacy of antenatal corticosteroids administration within 7 days before elective caesarean section (CS) in women with pre-gestational diabetes (PGDM) or gestational diabetes (GDM).

DESIGN

Triple blind, parallel group, placebo-controlled, pilot RCT.

SETTING

Single-centre tertiary maternity hospital in Melbourne, Australia.

POPULATION

Pregnant women with PGDM (type 1 or type 2 diabetes) or GDM booked for a planned CS scheduled between 35+0 and 38+6  weeks of gestation.

METHODS

Eligible participants were randomised to receive two injections of either betamethasone 11.4 mg or normal saline placebo, 24 hours apart within 7 days before CS scheduled between 35+0 and 38+6  weeks of gestation.

MAIN OUTCOME MEASURE

The proportion of eligible women who consented and were randomised.

TRIAL REGISTRATION

Australian and New Zealand Clinical Trials Registry ACTRN12619001475134.

RESULTS

Of 537 women eligible, 182 were approached and 47 (26%) were recruited. Of these, 22 were allocated to the betamethasone group and 25 were allocated to the placebo group. There were no serious adverse events related to participation.

CONCLUSION

It is feasible to undertake a triple-blind, placebo-controlled RCT investigating the efficacy of antenatal corticosteroids in preventing respiratory morbidity in infants of women with PGDM or GDM who are undergoing an elective CS between 35+0 and 38+6  weeks.

The Use of Antenatal Dexamethasone in Late Preterm and Term Pregnancies to Improve Neonatal Morbidity and Mortality: A Systematic Review and Meta-Analysis

There are no acceptable worldwide recommendations regarding the use of dexamethasone in late-preterm newborns delivered either vaginally or via cesarean section and term gestation that are performed via cesarean section. The present study aims to compare the effectiveness of antenatal intramuscular dexamethasone versus placebo/no-treatment in reducing neonatal respiratory complications in high-risk for imminent preterm birth in late preterm pregnancies and term pregnancies undergoing elective cesarean section. The PubMed, Scopus, and Cochrane Library databases were searched to assess the effectiveness of dexamethasone during late preterm and term gestation. The last literature search was performed on March 20th, 2022. Randomized controlled trials compared antenatal dexamethasone administration with placebo or no treatment. The outcomes of interest were: the incidence of Respiratory Distress Syndrome; Transient Tachypnea of the Newborn, Neonatal Intensive Care Unit admissions; and the need for ventilatory support or mechanical ventilation.

A standardized data form and three independent investigators performed the data extraction. Ten RCTs fulfilled our inclusion criteria. No statistically significant difference was found regarding all of the outcomes in the 34th-36th gestational week group. In the >37th gestational week group, a statistically significant difference was found regarding the incidence of RDS [RR (95% CI); p-value: 0.56 (0.36, 0.87); 0.01], TTN [RR (95% CI); p-value: 0.54 (0.42, 0.71); <0.00001], need for ventilatory support [RR (95% CI); p-value: 0.71 (0.52, 0.96); 0.03] and need for mechanical ventilation [RR (95% CI); p-value: 0.56 (0.33, 0.95); 0.03]. To conclude, the antenatal administration of dexamethasone can be considered to prevent neonatal complications and reduce perinatal morbidity in term pregnancies.

Antenatal Corticosteroids Decrease the Risk of Composite Neonatal Respiratory Morbidity in Planned Early Term Cesarean Deliveries

OBJECTIVE

While administration of antenatal corticosteroids prior to term elective cesarean deliveries has been shown in international randomized controlled trials to decrease the rates of respiratory distress syndrome and transient tachypnea of the newborn, this is not a standard practice in the United States. We aim to determine if the administration of antenatal corticosteroids for fetal lung maturation within 1 week of scheduled early term cesarean delivery resulted in decreased composite respiratory morbidity.

STUDY DESIGN

Historical cohort study including women who underwent scheduled early term cesarean delivery of a singleton, non-anomalous neonate at Mount Sinai Hospital between May 2015 and August 2019, comparing those who completed a course of antenatal corticosteroids within 1 week of delivery to those who did not. The primary outcome was composite respiratory morbidity defined as respiratory distress syndrome, transient tachypnea of the newborn, and neonatal intensive care unit admission for respiratory morbidity. Maternal and neonatal characteristics were compared between groups using t-tests or Wilcoxon-Rank Sum tests for continuous measures and Chi-square or Fisher's exact tests for categorical measures, as appropriate. The outcomes were assessed using logistic regression.

RESULTS

History of preterm birth was significantly higher in those who received antenatal corticosteroids compared with those who did not (24.0 vs. 10.9%, p = 0.01). Neonates who were not exposed to antenatal corticosteroids were more likely to experience the composite respiratory morbidity compared with those who were exposed (RR 4.1, 95% CI 1.2-13.7; p = 0.02). Between 37 and 38 weeks, neonates who did not receive steroids were at increased risk of composite respiratory morbidity (RR 11.7, 95% CI 1.5-89.0, p < 0.01), however, there was no difference for those born between 38 and 39 weeks.

CONCLUSION

Betamethasone course administered prior to planned early term cesarean delivery was associated with a statistically significant reduction in the neonatal composite respiratory morbidity compared with routine management.

KEY POINTS

· Steroids administered prior to scheduled cesarean lead to decreased neonatal respiratory morbidity.. · Steroid administration was not associated with increased adverse neonatal outcomes.. · Steroid administration was most beneficial between 37 and 38 weeks..

Antenatal corticosteroids prior to planned caesarean at term for improving neonatal outcomes

BACKGROUND

Infants born at term by elective caesarean section are more likely to develop respiratory morbidity than infants born vaginally. Prophylactic corticosteroids in singleton preterm pregnancies accelerate lung maturation and reduce the incidence of respiratory complications. It is unclear whether administration at term gestations, prior to caesarean section, improves the respiratory outcomes for these babies without causing any unnecessary morbidity to the mother or the infant.

OBJECTIVES

The objective of this review was to assess the effect of prophylactic corticosteroid administration before elective caesarean section at term, as compared to usual care (which could be placebo or no treatment), on fetal, neonatal and maternal morbidity. We also assessed the impact of the treatment on the child in later life.

SEARCH METHODS

For this update, we searched Cochrane Pregnancy and Childbirth's Trials Register, ClinicalTrials.gov (20 January 2021) and reference lists of retrieved studies.

SELECTION CRITERIA

We included randomised controlled trials comparing prophylactic antenatal corticosteroid administration (betamethasone or dexamethasone) with placebo or with no treatment, given before elective caesarean section at term (at or after 37 weeks of gestation). Quasi-randomised and cluster-randomised controlled trials were also eligible for inclusion.

DATA COLLECTION AND ANALYSIS

We used standard Cochrane Pregnancy and Childbirth methods for data collection and analysis. Two review authors independently assessed trials for inclusion, assessed risk of bias, evaluated trustworthiness (based on predefined criteria developed by Cochrane Pregnancy and Childbirth), extracted data and checked them for accuracy and assessed the certainty of the evidence using the GRADE approach. Our primary outcomes were respiratory distress syndrome (RDS), transient tachypnoea of the neonate (TTN), admission to neonatal special care for respiratory morbidity and need for mechanical ventilation. We planned to perform subgroup analyses for the primary outcomes according to gestational age at randomisation and type of corticosteroid (betamethasone or dexamethasone). We also planned to perform sensitivity analysis, including only studies at low risk of bias.

MAIN RESULTS

We included one trial in which participants were randomised to receive either betamethasone or usual care. The trial included 942 women and 942 neonates recruited from 10 UK hospitals between 1995 and 2002. This review includes only trials that met predefined criteria for trustworthiness. We removed three trials from the analysis that were included in the previous version of this review. The risk of bias was low for random sequence generation, allocation concealment and incomplete outcome data. The risk of bias for selective outcome reporting was unclear because there was no published trial protocol, and therefore it is unclear whether all the planned outcomes were reported in full. Due to a lack of blinding we judged there to be high risk of performance bias and detection bias. We downgraded the certainty of the evidence because of concerns about risk of bias and because of imprecision due to low event rates and wide 95% confidence intervals (CIs), which are consistent with possible benefit and possible harm Compared with usual care, it is uncertain if antenatal corticosteroids reduce the risk of RDS (relative risk (RR) 0.34 95% CI 0.07 to 1.65; 1 study; 942 infants) or TTN (RR 0.52, 95% CI 0.25 to 1.11; 1 study; 938 infants) because the certainty of evidence is low and the 95% CIs are consistent with possible benefit and possible harm. Antenatal corticosteroids probably reduce the risk of admission to neonatal special care for respiratory complications, compared with usual care (RR 0.45, 95% CI 0.22 to 0.90; 1 study; 942 infants; moderate-certainty evidence). The proportion of infants admitted to neonatal special care for respiratory morbidity after treatment with antenatal corticosteroids was 2.3% compared with 5.1% in the usual care group. It is uncertain if antenatal steroids have any effect on the risk of needing mechanical ventilation, compared with usual care (RR 4.07, 95% CI 0.46 to 36.27; 1 study; 942 infants; very low-certainty evidence). The effect of antenatal corticosteroids on the maternal development of postpartum infection/pyrexia in the first 72 hours is unclear due to the very low certainty of the evidence; one study (942 women) reported zero cases. The included studies did not report any data for neonatal hypoglycaemia or maternal mortality/severe mortality.

AUTHORS' CONCLUSIONS

Evidence from one randomised controlled trial suggests that prophylactic corticosteroids before elective caesarean section at term probably reduces admission to the neonatal intensive care unit for respiratory morbidity. It is uncertain if administration of antenatal corticosteroids reduces the rates of respiratory distress syndrome (RDS) or transient tachypnoea of the neonate (TTN). The overall certainty of the evidence for the primary outcomes was found to be low or very low, apart from the outcome of admission to neonatal special care (all levels) for respiratory morbidity, for which the evidence was of moderate certainty. Therefore, there is currently insufficient data to draw any firm conclusions.  More evidence is needed to investigate the effect of prophylactic antenatal corticosteroids on the incidence of recognised respiratory morbidity such as RDS. Any future trials should assess the balance between respiratory benefit and potential immediate adverse effects (e.g. hypoglycaemia) and long-term adverse effects (e.g. academic performance) for the infant. There is very limited information on maternal health outcomes to provide any assurances that corticosteroids do not pose any increased risk of harm to the mother.  Further research should consider investigating the effectiveness of antenatal steroids at different gestational ages prior to caesarean section. There are nine potentially eligible studies that are currently ongoing and could be included in future updates of this review.

Effectiveness of antenatal corticosteroids at term: Can we trust the data that 'inform' us?

Randomized controlled trials (RCTs) are a cornerstone for the assessment of the effectiveness of interventions. Appropriate randomization, design, sample size, statistical analyses, and conduct that reduces the risk of bias, enhance the chance they will deliver true research findings. The credibility of RCTs is difficult to assess without objective evidence of compliance with Good Clinical Practice standards. Remarkably, no mechanisms are in place both in the initial peer review process and during meta-analysis to assess these, and little guidance on how to assess data where research integrity cannot be confirmed (e.g. where data originated from a setting without established infrastructure or an era preceding current standards). We describe the case of the use of antenatal steroids. When these drugs are used in early preterm birth, their benefits outweigh the harms. However, later in pregnancy, and specifically at term, this balance is less clear. We describe that the four randomised clinical trials that inform clinical practice through the Cochrane meta-analysis, for various reasons, lack clear governance which makes it difficult to verify provenance and reliability of the data. We conclude that transparency and assessment of data credibility need to be inbuilt both at the time of publication and at the time of meta-analysis. This will drive up standards and encourage appropriate interpretation of results and the context from which they were derived.

Is there a Role for Antenatal Corticosteroids in Term Infants before Elective Cesarean Section?

OBJECTIVE

 Cesarean section (CS) delivery, especially without previous labor, is associated with worse neonatal respiratory outcomes. Some studies comparing neonatal outcomes between term infants exposed and not exposed to antenatal corticosteroids (ACS) before elective CS revealed that ACS appears to decrease the risk of respiratory distress syndrome (RDS), transient tachypnea of the neonate (TTN), admission to the neonatal intensive care unit (NICU), and the length of stay in the NICU.

METHODS

 The present retrospective cohort study aimed to compare neonatal outcomes in infants born trough term elective CS exposed and not exposed to ACS. Outcomes included neonatal morbidity at birth, neonatal respiratory morbidity, and general neonatal morbidity. Maternal demographic characteristics and obstetric data were analyzed as possible confounders.

RESULTS

 A total of 334 newborns met the inclusion criteria. One third of the population study (n = 129; 38.6%) received ACS. The present study found that the likelihood for RDS (odds ratio [OR] = 1.250; 95% confidence interval [CI]: 0.454-3.442), transient TTN (OR = 1.,623; 95%CI: 0.556-4.739), and NIUC admission (OR = 2.155; 95%CI: 0.474-9.788) was higher in the ACS exposed group, although with no statistical significance. When adjusting for gestational age and arterial hypertension, the likelihood for RDS (OR = 0,732; 95%CI: 0.240-2.232), TTN (OR = 0.959; 95%CI: 0.297-3.091), and NIUC admission (OR = 0,852; 95%CI: 0.161-4.520) become lower in the ACS exposed group.

CONCLUSION

 Our findings highlight the known association between CS-related respiratory morbidity and gestational age, supporting recent guidelines that advocate postponing elective CSs until 39 weeks of gestational age.

Antenatal corticosteroid administration for foetal lung maturation

Antenatal corticosteroids are an essential component in the management of women at risk for preterm labour. They promote lung maturation and reduce the risk of other preterm neonatal complications. This narrative review discusses the contentious issues and controversies around the optimal use of antenatal corticosteroids and their consequences for both the mother and the neonate. The most recent evidence base is presented.

Controversies in antenatal corticosteroid treatment

Antenatal corticosteroids are now established as one of the cornerstones of therapy in the prevention of neonatal morbidity and mortality prior to preterm birth. Although this practice is widely accepted, a significant number of controversies exist. This review explores the knowledge gaps regarding the use of antenatal corticosteroids in the preterm, late preterm and term populations. Furthermore, the role of antenatal corticosteroids in special populations, such as diabetes, multiple pregnancies and periviable gestations, where high-quality data from randomized controlled trials are lacking, is also considered.

No. 364-Antenatal Corticosteroid Therapy for Improving Neonatal Outcomes

OBJECTIVE

To assess the benefits and risks of antenatal corticosteroid therapy for women at risk of preterm birth or undergoing pre-labour Caesarean section at term and to make recommendations for improving neonatal and long-term outcomes.

OPTIONS

To administer or withhold antenatal corticosteroid therapy for women at high risk of preterm birth or women undergoing pre-labour Caesarean section at term.

OUTCOMES

Perinatal morbidity, including respiratory distress syndrome, intraventricular hemorrhage, bronchopulmonary dysplasia, infection, hypoglycemia, somatic and brain growth, and neurodevelopment; perinatal mortality; and maternal morbidity, including infection and adrenal suppression.

INTENDED USERS

Maternity care providers including midwives, family physicians, and obstetricians.

TARGET POPULATION

Pregnant women.

EVIDENCE

Medline, PubMed, Embase, and the Cochrane Library were searched from inception to September 2017. Medical Subject Heading (MeSH) terms and key words related to pregnancy, prematurity, corticosteroids, and perinatal and neonatal mortality and morbidity were used. Statements from professional organizations including that of the National Institutes of Health, the American College of Obstetricians and Gynecologists, the Society for Maternal Fetal Medicine, the Royal College of Obstetricians and Gynaecologists, and the Canadian Pediatric Society were reviewed for additional references. Randomized controlled trials conducted in pregnant women evaluating antenatal corticosteroid therapy and previous systematic reviews on the topic were eligible. Evidence from systematic reviews of non-experimental (cohort) studies was also eligible.

VALIDATION METHODS

This Committee Opinion has been reviewed and approved by the Maternal-Fetal Medicine Committee of the SOGC and approved by SOGC Council.

BENEFITS, HARMS, AND/OR COSTS

A course of antenatal corticosteroid therapy administered within 7 days of delivery significantly reduces perinatal morbidity/mortality associated with preterm birth between 24 + 0 and 34 + 6 weeks gestation. When antenatal corticosteroid therapy is given more than 7 days prior to delivery or after 34 + 6 weeks gestation, the adverse effects may outweigh the benefits. Evidence on long-term effects is scarce, and potential neurodevelopment harms are unquantified in cases of late preterm, term, and repeated exposure to antenatal corticosteroid therapy.

GUIDELINE UPDATE

Evidence will be reviewed 5 years after publication to evaluate the need for a complete or partial update of the guideline. If important evidence is published prior to the 5-year time point, an update will be issued to reflect new knowledge and recommendations.

SPONSORS

The guideline was developed with resources provided by the Society of Obstetricians and Gynaecologists of Canada with support from the Canadian Institutes of Health Research (APR-126338).

SUMMARY STATEMENTS

RECOMMENDATIONS: Gestational Age Considerations Agents, Dosage, Regimen, and Target Timing Subpopulations and Special Consideration.

N° 364 - La Corticothérapie Prénatale Pour Améliorer Les Issues Néonatales

OBJECTIF

Évaluer les avantages et les risques de la corticothérapie prénatale chez les femmes qui présentent un risque d'accouchement prématuré ou qui subissent une césarienne à terme avant début de travail, et formuler des recommandations visant l'amélioration des issues néonatales et des issues à long terme.

OPTIONS

Administrer ou ne pas administrer une corticothérapie prénatale aux femmes qui présentent un risque élevé d'accouchement prématuré ou qui subissent une césarienne avant travail à terme. RéSULTATS: Morbidité périnatale, notamment le syndrome de détresse respiratoire, l'hémorragie intraventriculaire, la dysplasie bronchopulmonaire, l'infection, l'hypoglycémie, ainsi que les troubles de la croissance somatique et cérébrale et du neurodéveloppement; mortalité périnatale; et morbidité maternelle, notamment l'infection et la suppression surrénalienne.

UTILISATEURS CIBLES

Fournisseurs de soins de maternité, notamment les sages-femmes, les médecins de famille et les obstétriciens.

POPULATION CIBLE

Femmes enceintes. ÉVIDENCE: Nous avons interrogé les bases de données Medline, PubMed et Embase ainsi que la Bibliothèque Cochrane, de leur création au mois de septembre 2017. Nous nous sommes servis de Medical Subjet Headings (MeSH) et de mots clés en lien avec la grossesse, la prématurité, les corticostéroïdes ainsi que la mortalité et la morbidité périnatales et néonatales. Nous avons également consulté les déclarations d'organismes professionnels tels que les National Institutes of Health, l'American College of Obstetricians and Gynecologists, la Society for Maternal-Fetal Medicine, le Royal College of Obstetricians and Gynaecologists et la Société canadienne de pédiatrie pour obtenir des références additionnelles. Les essais cliniques randomisés évaluant la corticothérapie prénatale menés sur des femmes enceintes et les revues systématiques antérieures sur le sujet étaient admissibles, tout comme les données venant de revues systématiques d'études non expérimentales (études de cohorte).

VALEURS

La présente opinion de comité a été révisée et approuvée par le Comité de médecine fœto-maternelle de la SOGC, et approuvée par le Conseil de la SOGC. AVANTAGES, INCONVéNIENTS ET COûTS: L'administration d'une corticothérapie prénatale dans les sept jours précédant l'accouchement réduit significativement la morbidité et la mortalité périnatales associées à la naissance prématurée survenant entre 24+0 et 34+6 semaines de grossesse. Si la corticothérapie prénatale est administrée plus de sept jours avant l'accouchement ou après 34+6 semaines de grossesse, les effets indésirables peuvent surpasser les avantages. Les données probantes sur l'impact à long terme de la corticothérapie prénatale sont rares. Par ailleurs, les effets neurodéveloppementaux néfastes potentiels de l'exposition répétée à la corticothérapie prénatale ou de l'administration de corticostéroïdes en période préterme tardive ou à terme n'ont pas été quantifiés. MIS-à-JOUR à LA DIRECTIVE: Une revue des données probantes sera menée cinq ans après la publication de la présente directive clinique afin d'évaluer si une mise à jour complète ou partielle s'impose. Si de nouvelles données probantes importantes sont publiées avant la fin de ces cinq ans, une mise à jour tenant compte des nouvelles connaissances et recommandations sera publiée.

COMMANDITAIRES

La présente directive clinique a été élaborée à l'aide de ressources fournies par la Société des obstétriciens et gynécologues du Canada et avec l'appui des Instituts de recherche en santé du Canada (APR-126338). MOTS CLéS: Corticothérapie prénatale, maturation fœtale, prématurité, période préterme tardive, césarienne avant travail DÉCLARATION SOMMAIRES: RECOMMANDATIONS: Considérations relatives à l'âge gestationnel.

Corticosteroids for preventing neonatal respiratory morbidity after elective caesarean section at term

BACKGROUND

Infants born at term by elective caesarean section are more likely to develop respiratory morbidity than infants born vaginally. Prophylactic corticosteroids in singleton preterm pregnancies accelerate lung maturation and reduce the incidence of respiratory complications.

OBJECTIVES

The objective of this review was to assess the effect of prophylactic corticosteroid administration before elective caesarean section at term, as compared to usual management without corticosteroids, in reducing neonatal respiratory morbidity and admission to special care with respiratory complications.

SEARCH METHODS

We searched Cochrane Pregnancy and Childbirth's Trials Register (14 June 2017), and reference lists of retrieved studies.

SELECTION CRITERIA

Randomised controlled trials comparing prophylactic antenatal corticosteroid administration (betamethasone or dexamethasone) with placebo or with no treatment, given before elective caesarean section at term (at or after 37 weeks of gestation).

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed trials for inclusion and risk of bias, extracted data and checked them for accuracy. We assessed the quality of the evidence using the GRADE approach.

MAIN RESULTS

We included four trials (3956 women and 3893 neonates) at a moderate risk of bias, comparing prophylactic administration of betamethasone or dexamethasone versus placebo or usual treatment without steroids in term elective caesarean section. Women randomised to treatment group received either two intramuscular doses of betamethasone in the 48 hours before delivery, or intramuscular dexamethasone (two or four doses) prior to delivery (at 37 weeks' gestation or 48 hours before delivery), and were compared to the control group who received a saline placebo or treatment as usual.Prophylactic antenatal corticosteroid administration appeared to decrease the risk of respiratory distress syndrome (RDS) (risk ratio (RR) 0.48; 95% confidence interval (CI) 0.27 to 0.87; 4 studies; 3817 participants; low-quality evidence), transient tachypnoea of the neonate (TTN) (RR 0.43; 95% CI 0.29 to 0.65; 4 studies; 3821 participants; low-quality evidence), admission to the neonatal intensive care unit (NICU) for respiratory morbidity (RR 0.42; 95% CI 0.22 to 0.79; 3 studies; 3441 participants), and admission to neonatal special care (all levels) for respiratory complications (RR 0.45; 95% CI 0.22 to 0.90; 1 study; 942 participants; low-quality evidence). Administration of antenatal corticosteroids also appeared to reduce admission to neonatal special care (RR 0.62; 95% CI 0.43 to 0.89; 2 studies; 2169 participants) and neonatal intensive care (RR 0.14; 95% CI 0.03 to 0.61; 1 study; 452 participants) for any indication, compared to placebo or usual care. Finally, prophylactic antenatal corticosteroids also appeared to reduce the length of stay in NICU by 2.70 days (mean difference (MD) -2.70; 95% CI -2.76 to -2.64; 2 studies; 32 participants).No reduction was found in the need for mechanical ventilation (RR 0.67; 95% CI 0.27 to 1.68; 3 studies; 3441 participants; very-low quality), perinatal death (RR 0.67; 95% CI 0.11 to 4.10; 4 studies; 3893 participants) or neonatal sepsis (RR 1.00; 95% CI 0.06 to 15.95; 2 studies; 2214 participants) .There were no reported events of neonatal respiratory complications (other than RDS and tachypnoea of the newborn (TTN)), chronic lung disease, duration of mechanical ventilation or maternal postpartum infection, therefore results on these outcomes are non-estimable. The studies did not provide data on other pre-defined outcomes.The quality of evidence, as assessed using GRADE was low for the outcomes of RDS, TTN and admission to NICU for respiratory morbidity, indicating that the true effect could potentially be substantially different from our estimate of effect.

AUTHORS' CONCLUSIONS

The results from the four trials are promising, but more high-quality studies with larger sample sizes that are adequately powered to detect the effect of prophylactic antenatal corticosteroids on outcomes of respiratory morbidity are needed, given the potential of the current studies for bias. Consideration should be given to the balance between statistical significance and clinical significance, particularly in view of the low event rates of significant respiratory morbidity (RDS or admission to NICU for respiratory complications) in this population. In addition, further trials on the long-term outcomes of these infants are needed to identify any potential harms and complications of antenatal corticosteroid administration at term.

Antenatal corticosteroids: an assessment of anticipated benefits and potential risks

Antenatal corticosteroids are standard of care for pregnancies at risk of preterm delivery between 24-34 weeks' gestational age. Recent trials demonstrate modest benefits from antenatal corticosteroids for late preterm and elective cesarean deliveries, and antenatal corticosteroids for periviable deliveries should be considered with family discussion. However, many women with threatened preterm deliveries receive antenatal corticosteroids but do not deliver until >34 weeks or at term. The net effect is that a substantial fraction of the delivery population will be exposed to antenatal corticosteroids. There are gaps in accurate assessments of benefits of antenatal corticosteroids because the randomized controlled trials were performed prior to about 1990 in pregnancies generally >28 weeks. The care practices for the mother and infant survival were different than today. The randomized controlled trial data also do not strongly support the optimal interval from antenatal corticosteroid treatment to delivery of 1-7 days. Epidemiology-based studies using large cohorts with >85% of at-risk pregnancies treated with antenatal corticosteroids probably overestimate the benefits of antenatal corticosteroids. Although most of the prematurity-associated mortality is in low-resource environments, the efficacy and safety of antenatal corticosteroids in those environments remain to be evaluated. The short-term benefits of antenatal corticosteroids for high-risk pregnancies in high-resource environments certainly justify antenatal corticosteroids as few risks have been identified over many years. However, cardiovascular and metabolic abnormalities have been identified in large animal models and cohorts of children exposed to antenatal corticosteroids that are consistent with fetal programming for adult diseases. These late effects of antenatal corticosteroids suggest caution for the expanded use of antenatal corticosteroids beyond at-risk pregnancies at 24-34 weeks. A way forward is to develop noninvasive fetal assessments to identify pregnancies across a wider gestational age that could benefit from antenatal corticosteroids.