Antenatal corticosteroids in the late preterm period: A prospective cohort study

The World Health Organization Antenatal CorTicosteroids for Improving Outcomes in preterm Newborns (ACTION-III) Trial: study protocol for a multi-country, multi-centre, double-blind, three-arm, placebo-controlled, individually randomized trial of antenatal corticosteroids for women at high probability of late preterm birth in hospitals in low- resource countries

BACKGROUND

Preterm birth complications are the leading cause of newborn and under-5 mortality. Over 85% of all preterm births occur in the late preterm period, i.e. between 34 and < 37 weeks of gestation. Antenatal corticosteroids (ACS) prevent mortality and respiratory morbidity when administered to women at high risk of an early preterm birth, i.e. < 34 weeks' gestation. However, the benefits and risks of ACS in the late preterm period are less clear; both guidelines and practices vary between settings. Emerging evidence suggests that the benefits of ACS may be achievable at lower doses than presently used. This trial aims to determine the efficacy and safety of two ACS regimens compared to placebo, when given to women with a high probability of late preterm birth, in hospitals in low-resource countries.

METHODS

WHO ACTION III trial is a parallel-group, three-arm, individually randomized, double-blind, placebo-controlled trial of two ACS regimens: dexamethasone phosphate 4 × 6 mg q12h or betamethasone phosphate 4 × 2 mg q 12 h. The trial is being conducted across seven sites in five countries-Bangladesh, India, Kenya, Nigeria, and Pakistan. Eligible women are those with a gestational age between 34 weeks 0 days and 36 weeks 5 days, who have a high probability of preterm birth between 12 h and 7 days (up to 36 weeks 6 days gestation). The primary outcome is a composite of stillbirth or neonatal death within 72 h of birth or use of newborn respiratory support within 72 h of birth or prior to discharge from hospital, whichever is earlier. Secondary outcomes include safety and health utilization measures for both women and newborns. The sample size is 13,500 women.

DISCUSSION

This trial will evaluate the benefits and possible harms of ACS when used in women likely to have a late preterm birth. It will also evaluate a lower-dose ACS regimen based on literature from pharmacokinetic studies. The results of this trial will provide robust critical evidence on the safe and appropriate use of ACS in the late preterm period internationally.

TRIAL REGISTRATION

ISRCTN11434567 . Registered on 7 June 2021.

Equivalence of single and standard doses of antenatal corticosteroids for late preterm neonatal outcomes: insights from a secondary analysis

BACKGROUND

The recent paradigm shift of treating individuals at risk of late preterm birth with antenatal corticosteroids warrants an assessment of the effect of single dosage.

OBJECTIVE

To compare outcomes of neonates born in the late preterm period (34.0-36.6 weeks) after a single dose of antenatal corticosteroids vs placebo.

STUDY DESIGN

We performed a secondary analysis of the Antenatal Late Preterm Steroids trial. All individuals enrolled in the parent trial who received only a single dose of either antenatal corticosteroids or placebo and delivered within 24 hours were included. Primary outcome was a composite of respiratory support at 72 hours, including continuous positive airway pressure or high-flow nasal cannula ≥2 hours, oxygen with an inspired fraction of ≥30% for ≥4 hours, or mechanical ventilation.

RESULTS

Of the 2831 individuals in the parent trial, 1083 (38.3%) met inclusion criteria; of them, 539 (49.8%) received a single dose of antenatal corticosteroids and 544 (50.2%) a single placebo dose. The placebo and antenatal corticosteroids groups had similar demographic and clinical characteristics. There was no difference in the rate of the primary respiratory outcome (adjusted risk ratio, 1.12; 95% confidence interval, 0.85-1.47) or in the rate of respiratory distress syndrome (adjusted risk ratio, 1.47; 95% confidence interval, 0.95-2.26) between those who received a single antenatal corticosteroids dose and placebo. An exploratory stratification by randomization-to-delivery intervals of 12-hour increments also showed no association with lower primary respiratory outcome rates.

CONCLUSION

In individuals with late preterm birth pregnancies who received antenatal corticosteroids and delivered before a second dose, there were no differences in neonatal respiratory morbidities compared with placebo. However, this study is not powered to detect treatment efficacy.

The role of antenatal corticosteroids in twin pregnancy

Twin pregnancy was associated with significantly higher rates of adverse neonatal and perinatal outcomes. One of the underlying causes is that twins are prone to preterm birth. Antenatal corticosteroids are widely used for reducing the incidence of neonatal respiratory distress syndrome initially and other neonatal mortality and morbidities subsequently. As it is widely used as a prophylactic treatment for potential premature births, there remain controversies of issues relating to twin gestations, including window for opportunity, timing of use, repeat course, optimal administration-to-delivery intervals, dosage, and type of corticosteroid. Thus, we present a thorough review of antenatal corticosteroids usage in twin gestation, emphasizing the aforementioned issues and attempting to offer direction for future investigation and clinical practice.

Impact on neonatal morbidities after a change in policy to administer antenatal corticosteroids to mothers at risk for late preterm delivery

OBJECTIVES

Antenatal corticosteroids (ACS) administered to mothers at risk for preterm delivery before 34 weeks has been standard care to improve neonatal outcomes. After introducing a new obstetric policy based on updated recommendations advising the administration of ACS to pregnant women at risk for late preterm (LPT) delivery (34-36 6/7 weeks), we set out to determine the short-term clinical impact on those LPT neonates.

METHODS

Retrospective chart review of LPT neonates delivered at NYU Langone Medical Center both one year before and after the policy went into place. We excluded subjects born to mothers with pre-gestational diabetes, multiple gestations, and those with congenital/genetic abnormalities. We also excluded subjects whose mothers already received ACS previously in pregnancy. Subjects were divided into pre-policy and post-policy groups. Neonatal and maternal data were compared for both groups.

RESULTS

388 subjects; 180 in the pre-policy and 208 in the post-policy group. This policy change resulted in a significant increase in ACS administration to mothers who delivered LPT neonates (67.3 vs. 20.6%, p<0.001). In turn, there was a significant reduction in LPT neonatal intensive care unit (NICU) admissions (44.2 vs. 54.4%, p=0.04) and need for respiratory support (27.9 vs. 42.8%, p<0.01). However, we also found an increased incidence of hypoglycemia (49.5 vs. 28.3%, p<0.001).

CONCLUSIONS

This LPT ACS policy appears effective in reducing the need for LPT NICU level care overall. However, clinicians must be attentive to monitor for adverse effects like hypoglycemia, and there remains a need for better understanding of potential long-term impacts.

Does antenatal corticosteroid therapy improve neonatal outcomes in late preterm birth?

BACKGROUND

Infants who are born at 34°^/7 to 36^6/7weeks of gestation (late preterm) are at greater risk for respiratory and other neonatal morbidities. The objective of this study was to examine the effects of the administration of antenatal corticosteroids (ACS) to women at risk for late preterm delivery on the incidence of neonatal outcomes.

METHOD

This was a prospective cohort study of singleton gestations at risk of imminent delivery between 34°^/7 and 36^6/7weeks. Neonatal outcomes were compared between mothers who received ACS and those who did not. The primary outcome was the rate of composite respiratory morbidity defined as the need for treatment within 72 h of life (continuous positive airway pressure or high flow nasal cannula for least 2 h or supplemental oxygen with a fraction of inspired oxygen of at least 0.30 for at least four continuous hours or mechanical ventilation).

RESULTS

During the 3-year study period, 595 subjects were included in this study, comprising 234 subjects that received ACS and 361 that did not. Administration of ACS significantly reduced the rates of composite respiratory morbidity (aOR 0.63 95% CI 0.40-0.99), the use of CPAP or HFNC for at least 2 h (aOR 0.57 95% CI 0.35-0.94), and transient tachypnea of the newborn (aOR 0.48 95% CI 0.28-0.82). Neonatal hypoglycemia was more significantly increased in the ACS group compared with controls (aOR 1.64 95% CI 1.04-2.59). We found no significant between-group differences in the rate of respiratory distress syndrome, surfactant use, need for resuscitation, jaundice requiring phototherapy, admission to neonatal intensive care or special care nursery, and duration of hospitalization.

CONCLUSION

Administration of ACS during the late preterm period decreased neonatal respiratory complications, however, increased the rate of hypoglycemia.

Comparison of neonatal outcomes with and without the administration of betamethasone in late preterm births

OBJECTIVE

To evaluate the effects of antenatal steroid administration on neonatal outcomes in late preterm births.

METHODS

Demographic and neonatal data from women who gave birth between May 2018 and March 2021 at 34⁺⁰ -36⁺⁶  weeks of gestation were screened from the information system of the hospital. The patients were assigned to two groups: those who were and those who were not given steroids. All parameters were compared between the two groups.

RESULTS

The 1-minute (9 versus 8) and 5-minute (10 versus 9) Apgar scores, need for a neonatal intensive care unit (NICU) stay (23.7% versus 27.8%), length of stay (Day) in the NICU (1.97 ± 0.24 versus 2.45 ± 0.16), rate of transient tachypnea of the newborn (3.3% versus 7.8%), respiratory distress syndrome (2.5% versus 5.2%), need for mechanical ventilation (1.2% versus 3.8%), and neonatal sepsis (1% versus 2.6%) were lower in the group that received betamethasone compared with the group that did not; the differences between the two groups were statistically significant.

CONCLUSION

Based on the results of the present study, we believe that antenatal steroid administration would be beneficial before late preterm births occurring between 34⁺⁰ and 36⁺⁶  weeks of pregnancy, considering the significant reduction in various respiratory complications, especially in respiratory distress syndrome and the need for an NICU stay.

Antenatal dexamethasone use and respiratory distress in late preterm infants: results from first Vietnamese matched cohort study

BACKGROUND

Respiratory distress syndrome (RDS) is one of the leading causes of early neonatal morbidity and mortality in late preterm infants (LPIs) worldwide. This matched cohort study aimed to assess how the antenatal dexamethasone use affect the respiratory distress (RD) proportion in preterm newborns between 34 0/7 weeks and 36 6/7 weeks of gestation.

METHODS

This was a prospective cohort study on 78 women with singleton pregnancy who were in threatened preterm birth and had not received prior dexamethasone, who were admitted between 34 0/7 weeks and 36 6/7 weeks at Hue University of Medicine and Pharmacy Hospital from June 2018 to May 2020. The matched control group without dexamethasone use included 78 pregnant women diagnosed with threatened late preterm births who were at similar gestational ages and estimated fetal weights as the treatment group. The treatment group received 6 mg intramuscular dexamethasone every 12 h for a total of 4 doses or until delivery. Primary outcome was the rate of neonatal RD. Secondary neonatal outcomes included the need for respiratory support, neonatal intensive care unit (NICU) admission, hypoglycemia, necrotizing enterocolitis, intraventricular hemorrhage, and neonatal death. Statistical analyses were performed by using SPSS software, version 26.0.

RESULTS

The proportion of RD in LPI was significantly lower in the treatment group than in the matched control group (10.3% vs. 23.1%, respectively), adjusted Odds Ratio [aOR] 0.29; 95% confidence interval [CI] 0.10 - 0.83 and p = 0.021. Neonatal hypoglycemia was more common in the dexamethasone group than in the matched group (25.6% vs. 12.8%, respectively; aOR, 2.59; 95% CI, 1.06 - 6.33; p = 0.037). There were no significant between-groups differences in the incidence of respiratory support, NICU admission or length of hospital stay.

CONCLUSIONS

Administration of antenatal dexamethasone to women at risk for late preterm birth could help to lower the proportion of respiratory distress in late preterm infants.

Antenatal corticosteroids affecting enteral feeding and growth of preterm infants: A retrospective cohort study

BACKGROUND

Treatment of antenatal corticosteroids (ACSs) to women at risk of preterm labor can decrease neonatal mortality and morbidity. However, effect of ACS exposure on enteral feeding and body growth of preterm infants remains elusive.

METHODS

This retrospective study collected information of eligible singleton infants born between 22⁺⁰ and 36⁺⁶ weeks' gestation from 2017 to 2019. Logistic regression and multivariate linear regression were adopted to examine the associations of the ACS exposure with various outcomes of enteral feeding and growth considering potential confounders. Stratified analysis was performed based on gestational age (GA) (<34 vs ≥34 weeks).

RESULTS

Of the 1694 preterm infants included, 1222 (72.1%) were exposed to ACSs. Infants with ACS exposure had a higher incidence of feeding intolerance (odds ratio 1.51; 95% CI, 1.05 to 2.20; P = .03), slower advancement of enteral feeding (β coefficient -0.86; 95% CI, -1.48 to -0.25; P = .01), and lower delta body-weight z-scores (β coefficient-0.13; 95% CI, -0.18 to -0.08; P < .001). Unlike in infants with GA <34 weeks, ACS exposure was associated with slower advancement of enteral feeding, longer time to regain birth weight, and lower delta body-weight z-scores in the ones with GA ≥34 weeks.

CONCLUSION

ACS exposure is associated with poorer enteral feeding process and body growth in our study population, which is more prominent in late preterm infants. A multicenter prospective study and mechanistic studies using animal models are required.

Neonatal hypoglycemia after initiation of late preterm antenatal corticosteroids

OBJECTIVE

To compare the frequency and severity of neonatal hypoglycemia in pregnancies treated with and without late preterm antenatal corticosteroids.

STUDY DESIGN

We conducted a retrospective cohort study of late preterm deliveries at LAC + USC (2015-2018). Neonatal outcomes were compared between pregnancies treated with and without corticosteroids.

RESULTS

93 pregnancies (39.9%) received corticosteroids and 140 (60.1%) did not. Neonates born to women given corticosteroids were more likely to be hypoglycemic (47.3 vs. 29.3%, OR_adj 2.25, p_adj = 0.01). The mean initial glucose (45.6 mg/dL vs. 51.9 mg/dL, p = 0.01) and glucose nadir (39.1 mg/dL vs. 45.4 mg/dL, p < 0.001) were significantly lower if the neonates received corticosteroids. Neonates admitted to the NICU solely for hypoglycemia were more likely to be born to women treated with corticosteroids (OR_adj 4.71, p_adj = 0.01).

CONCLUSION

Administration of late preterm corticosteroids was associated with an increased incidence and severity of neonatal hypoglycemia.

Does antenatal corticosteroid therapy improve neonatal outcomes in late preterm birth?

BACKGROUND

Infants who are born at 34^0/7 to 36^6/7 weeks of gestation (late preterm) are at greater risk for respiratory and other neonatal morbidities. The objective of this study was to examine the effects of administration of antenatal corticosteroids (ACSs) to women at risk for late preterm delivery on the incidence of neonatal outcomes.

METHODS

This was a prospective cohort study of singleton gestations at risk of imminent delivery between 34^0/7 and 36^6/7 weeks. Neonatal outcomes were compared between mothers who received ACS and those who did not. Primary outcome was the rate of composite respiratory morbidity defined as the need for treatment within 72 h of life (continuous positive airway pressure or high flow nasal cannula for least 2 h or supplemental oxygen with a fraction of inspired oxygen of at least 0.30 for at least four continuous hours or mechanical ventilation).

RESULTS

During the 3-year study period, 595 subjects were included in this study, comprising 234 subjects that received ACS and 361 that did not. Administration of ACS significantly reduced the rates of composite respiratory morbidity (adjusted odds ratio (aOR) 0.63, 95% confidence interval (CI) 0.40-0.99), the use of CPAP or HFNC for at least 2 h (aOR 0.57, 95% CI 0.35-0.94) and transient tachypnea of newborn (aOR 0.48, 95% CI 0.28-0.82). Neonatal hypoglycemia was more significantly increased in the ACS group compared with controls (aOR 1.64, 95% CI 1.04-2.59). We found no significant between-group differences in the rate of respiratory distress syndrome, surfactant use, need for resuscitation, jaundice requiring phototherapy, admission to neonatal intensive care or special care nursery and duration of hospitalization.

CONCLUSION

Administration of ACS during the late preterm period decreased neonatal respiratory complications, however, increased the rate of hypoglycemia.

Determinants of neonatal hypoglycemia after antenatal administration of corticosteroids (ACS) for lung maturation: Data from two referral centers and review of the literature

BACKGROUND

A correlation between ACS and neonatal hypoglycemia has been recently demonstrated.

AIMS

The aim of the study was to evaluate the determinants of neonatal hypoglycemia in women exposed to ACS for respiratory distress syndrome prevention.

MATERIAL AND METHODS

Retrospective, multicenter, cohort study conducted in two Tertiary University Units. All fetuses delivered from 2016 to 2017 after ACS (two doses i.m. of Betamethasone 12 mg 24 h apart) were considered eligible for the study purpose. The primary outcome was the incidence of hypoglycemia, defined as a glycemic value ≤45 mg/dl within the first 48 h of neonatal life. The effect on neonatal glycaemia due to timing (interval from exposure to delivery) and type (single completed, single partial or repeated course) of ACS administration was also assessed.

RESULTS

Overall, 99 neonates met the inclusion criteria. Hypoglycemia occurred in 38/99 (38.4%) of the included newborns. Compared to normoglycemic neonates, those with hypoglycemia had lower gestational age at delivery (33.06 ± 3.37 vs. 35.94 ± 3.17 g; p < 0.0001). Lower birthweight (1747.28 ± 815.29 vs. 2499.24 ± 780.51 g; p < 0.0001), a shorter interval time from administration to delivery (1.85 ± 2.59 vs. 3.34 ± 3.39 weeks; p = 0.02) and a higher incidence of single partial course (23.7 vs. 8.72%; p = 0.03). Multivariate logistic regression found that only birthweight was significantly associated with neonatal hypoglycemia (OR 0.4 95% CI -1.16/-0.04; p < 0.038).

CONCLUSION

Hypoglycemia occurs in a large proportion of fetuses exposed to ACS independently from the type of exposure (single partial/single completed) and from the time interval between ACS administration and delivery. Birthweight seems to be the strongest determinant for the occurrence neonatal hypoglycemia after antenatal administration of steroids for lung maturation.

The place of antenatal corticosteroids in late preterm and early term births

Infants born in the late preterm period and via non-labour caesarean section in the early term period are at increased risk of respiratory morbidity when compared to their term-born counterparts. The morbidity in these infants is less frequent and severe than in early preterm infants. Antenatal corticosteroids reduce respiratory morbidity in these populations; however, the magnitude of the reduction appears to be small and predominantly in the self-limiting condition of transient tachypnoea of the neonate. The smaller benefit, along with possible harmful effects of corticosteroids, raises a question about the role of antenatal corticosteroids in this population. Special obstetric populations such as twin pregnancies and pregnancies complicated by diabetes and growth restriction are at increased risk of prematurity and more vulnerable to its complications. Nevertheless, there is limited evidence regarding the benefits of corticosteroids in these populations and potential concern regarding adverse effects. We recommend an individualised approach when administering corticosteroids at later gestations. In these specific obstetric populations, we do not currently recommend administering corticosteroids in the late preterm/early term periods until more evidence is available.

Evaluation of the effect of antenatal betamethasone on neonatal respiratory morbidities in late preterm deliveries (34-37 weeks)

Background: Since late preterm neonates (34-36 weeks) are more at risk of respiratory morbidities, the present study was conducted to evaluate the effect of antenatal betamethasone on neonatal respiratory morbidities in women with late preterm delivery.Methods: This randomized clinical trial was performed on 240 women with single pregnancy that was at high risk of late preterm delivery (34-37 weeks). The patients were randomly assigned to either betamethasone (intramuscular injection of 12 mg of betamethasone in two doses with an interval of 24 hours) or the control group. The two groups were compared with each other in terms of respiratory morbidities, NICU admission and its cause and duration, hospitalization in the neonatal ward for more than 6 hours, and the duration of hospitalization.Results: Of all, 79 neonates (33%) had one or more respiratory morbidities. The observed morbidities in the betamethasone group were significantly less prevalent than those in the control group (19 neonates (16%) and 60 neonates (50%), respectively, p < .001). The most frequently observed respiratory morbidity was needed for oxygen for more than an hour (34 infants, 14%). The need for oxygen for more than an hour, the need for continuous positive airway pressure (CPAP), respiratory distress syndrome (RDS), and the need for surfactant were significantly less observed in betamethasone group than in the control group. A total of 43 neonates (18%) were admitted to NICU and then hospitalized in the neonatal ward; the number of admitted neonates were significantly lower in the betamethasone group than in the control group (11 neonates (9%) and 32 neonates (27%), respectively, p < .001). Moreover, 15 neonates (6%) were admitted to the neonatal ward and there were no significant differences between the betamethasone and control groups (10 neonates (8%) and 5 neonates (4%), respectively, p = .182). Totally, 58 neonates (24%) were hospitalized; the number of hospitalized neonates was significantly lower in the betamethasone group than in the control group (21 neonates (18%) and 37 neonates (31%), respectively, p = .016).Conclusion: The results of this study showed that the antenatal administration of betamethasone in late preterm delivery (34-37 weeks) can improve respiratory morbidities and decrease the frequency of NICU admission.

Antenatal corticosteroid therapy: Historical and scientific basis to improve preterm birth management

OBJECTIVE

The purpose of this review is to describe the historical and scientific basis of antenatal corticosteroids (ACS) therapy, to improve the management of preterm birth and decreasing rates of respiratory distress syndrome, intraventricular hemorrhage, necrotizing enterocolitis and perinatal mortality in premature infants.

STUDY DESIGN

We searched MEDLINE/PubMed electronic database, the Cochrane Library, using medical subheading search words such as "ACS", "corticosteroids", "betamethasone" or "dexamethasone", matching with "preterm birth".

RESULTS

This practice was initiated by Liggins and Howie in 1972 and is supported by the initial comprehensive meta-analysis of Crowley, Chambers and Keirse, in 1990, the NIH Consensus Development Conference in 1994, the second Consensus Conference to evaluate repeated courses of corticosteroids in 2000 and the practice recommendations of obstetric societies worldwide. ACS therapy before anticipated preterm birth is one of the most important antenatal therapies and an important evidence-based practice for reducing mortality, and decreasing rates of complications in premature infants.

CONCLUSIONS

Today, there is no controversy that women with preterm birth <34 weeks should be ACS treated. Actually, rescue courses are recommended; while multiple, serial, repeated or weekly courses, are not recommended. In any clinical conditions, as preterm premature rupture of membranes, multiple pregnancies, severe preeclampsia/HELLP syndrome and fetal growth restriction; ACS is recommended.

Impact of preterm birth on the developing myocardium of the neonate

BackgroundGlobally, ∼10% of infants are born before full term. Preterm birth exposes the heart to the demands of postnatal cardiovascular function before cardiac development is complete. Our aim was to examine, in hearts collected from infants at autopsy, the effects of preterm birth on myocardial structure and on cardiomyocyte development.Methods and resultsHeart tissue was collected at perinatal autopsies of 16 infants who died following preterm birth between 23 and 36 weeks of gestation, and survived for 1-42 days; the hearts of 37 appropriately grown stillborn infants, aged 20-40 weeks of gestation, were used for comparison. Using confocal microscopy and image analysis, cardiomyocyte proliferation, maturation, ploidy, and size were quantified, and interstitial collagen and myocardial capillarization were measured. Preterm birth resulted in a marked reduction in the proliferation of cardiomyocytes relative to age-matched stillborn infant controls (preterm vs. control P<0.0001). In contrast, preterm birth did not affect heart weight, capillarization, interstitial collagen or cardiomyocyte maturation, ploidy, and size.ConclusionsPreterm birth appears to lead to an abrupt reduction in cardiomyocyte cell division. This reduced cardiomyocyte proliferation in preterm infants may adversely impact upon the final number of cardiomyocytes which may reduce cardiac functional reserve, and impair the reparative capacity of the myocardium.

Evaluation of prenatal corticosteroid use in spontaneous preterm labor in the Brazilian Multicenter Study on Preterm Birth (EMIP)

OBJECTIVE

To evaluate prenatal corticosteroid use in women experiencing spontaneous preterm labor and preterm delivery.

METHODS

The present cross-sectional multicenter study analyzed interview data from patients attending 20 hospitals in Brazil owing to preterm delivery between April 1, 2011 and July 30, 2012. Patients were stratified based on preterm delivery occurring before 34 weeks or at 34-36⁺⁶  weeks of pregnancy, and the frequency of prenatal corticosteroid use at admission was compared. Prenatal corticosteroid use, sociodemographic data, obstetric characteristics, and neonatal outcomes were examined.

RESULTS

There were 1455 preterm deliveries included in the present study; 527 (36.2%) occurred before 34 weeks of pregnancy and prenatal corticosteroids were used in 285 (54.1%) of these pregnancies. Among neonates delivered at 32-33⁺⁶  weeks, prenatal corticosteroid use was associated with lower pneumonia (P=0.026) and mortality (P=0.029) rates. Among neonates delivered at 34-36⁺⁶  weeks, prenatal corticosteroid use was associated with longer neonatal hospital admission (P<0.001), and an increased incidence of 5-minute Apgar scores below 7 (P=0.010), endotracheal intubation (P=0.042), surfactant use (P=0.006), neonatal morbidities (P=0.048), respiratory distress (P=0.048), and intraventricular hemorrhage (P=0.023).

CONCLUSION

Preterm labor and late preterm delivery were associated with worse neonatal outcomes following prenatal corticosteroids. This could reflect a sub-optimal interval between administration and delivery.

Antenatal corticosteroids beyond 34 weeks gestation: What do we do now?

The practice of antenatal corticosteroid administration in pregnancies of 24-34 weeks of gestation that are at risk of preterm delivery was adopted over 20 years after the first randomized clinical trial in humans. It is biologically plausible that antenatal corticosteroid in pregnancies beyond 34 weeks of gestation would reduce rates of respiratory morbidity and neonatal intensive care admission. Mostly guided by the results of a large multicenter randomized trial of antenatal corticosteroid in late preterm infants, the Antenatal Late Preterm Steroids Trial, the American Congress of Obstetricians and Gynecologists has released a practice advisory that the "administration of betamethasone may be considered in women with a singleton pregnancy between 34 0/7 and 36 6/7 weeks of gestation at imminent risk of preterm birth within 7 days." However, many unanswered questions about the risks and benefits of antenatal corticosteroids in this population remain and should be considered with the adoption of this treatment recommendation. This review of the literature indicates that the greatest effect is in the reduction of transient tachypnea of the newborn infant, which is a mostly self-limited condition. This benefit must be weighed against unanticipated outcomes, such as neonatal hypoglycemia, and unknowns about long-term neurodevelopmental follow up and metabolic risks. Amelioration of respiratory morbidity in late preterm infants does not preclude these infants from having other complications that are related to prematurity that require intensive care. Other possible morbidities of prematurity may be magnified if these babies no longer have respiratory symptoms. Conversely, if these late preterm babies no longer exhibit respiratory symptoms and "look good," they may be discharged before other morbidities of prematurity have resolved and be at risk for readmission. Furthermore, it is also important to ensure that unintended consequences are avoided to achieve a minor benefit. Some of these consequences may include treatment with multiple steroid courses or "treatment creep" in women at 34 to <37 weeks of gestation who do not meet the inclusion/exclusion criteria of the Antenatal Late Preterm Steroids Trial, particularly when a high percentage of women do not receive antenatal corticosteroid within 7 days of delivery. Finally, we believe that caution should be exercised before wide-scale universal adoption of antenatal corticosteroid for pregnancies that are at risk of preterm birth at 34 to <37 weeks of gestation, when it is unclear whether there are long-term effects. For a more balanced rationale for the decision to use antenatal corticosteroid treatment in pregnancies at >34 weeks of gestation, we urge for ongoing research into the risks and benefits of antenatal corticosteroid use in preterm infants overall, for better prediction of preterm birth so that antenatal corticosteroid can be administered within the ideal time frame, and for long-term neurodevelopmental follow-up of the participants in the large randomized Antenatal Late Preterm Steroids Trial.