US Incidence of Late-Preterm Steroid Use and Associated Neonatal Respiratory Morbidity After Publication of the Antenatal Late Preterm Steroids Trial, 2015-2017

Antenatal Late Preterm Steroids: The Evolution of the ALPS Trial

The Antenatal Late Preterm Steroids (ALPS) trial was designed to address respiratory morbidity common in infants born late preterm. The study was published in April, 2016 and, shortly thereafter, changed clinical practice in obstetrics in the United States. The following chapter describes the ALPS trial study design in detail, including the background leading to the trial, the study outcomes, and the initial findings of the long-term follow-up study. The ALPS story would not be complete without Elizabeth Thom, PhD, who died before her time. Her brilliance largely contributed to the design of the ALPS trial.

Antenatal corticosteroids: an updated assessment of anticipated benefits and potential risks

Antenatal steroid therapy is increasingly central to the obstetrical management of women at imminent risk of preterm birth. For women likely to deliver between 24 and 34 weeks' gestation, antenatal steroid therapy is the standard of care, conferring sizable benefits and few risks in high-resource environments when appropriately targeted. Recent studies have focused on antenatal steroid use in periviable and late preterm populations, and in term cesarean deliveries. As a result, antenatal steroid therapy has now been applied from 22 to 39+6 weeks of estimated gestational age. There is also an increased appreciation that the vast majority of randomized control data informing the use of antenatal steroids are derived from predominantly high-resource, White populations. Accordingly, a sizable amount of work has recently been undertaken to test how to safely use antenatal steroids in low- and middle-resource environments, wherein the often high rates of preterm birth make these low-cost, easily administered interventions an attractive proposition. It is likely underappreciated by the obstetrical and neonatal communities that the overall efficacy of antenatal steroid therapy is highly variable (including when preterm risk is accurately assessed), the treatment regimens used are largely arbitrary, dosing is suprapharmacologic for effect, and the benefit-risk balance is significantly and differentially modified by gestation. It is also very likely that the patients consenting to receive these treatments are similarly unaware of the complex balance of potential benefits and harms. Although a small number of follow-up studies present a generally benign picture of long-term antenatal steroid risk, several large, population-based retrospective studies have identified associations between antenatal steroid use, childhood mental disease, and newborn infections that warrant urgent attention. Of particular contemporary importance are emergent efforts to optimize antenatal steroid regimens on the basis of the pharmacokinetics and pharmacodynamics of the agents themselves, the need for better targeting of these potent drugs, and clear articulation of the potential benefits and harms of antenatal steroid use at differing stages of pregnancy and in different delivery contexts.

Gestational diabetes mellitus and late preterm birth: outcomes with and without antenatal corticosteroid exposure

BACKGROUND

Unlike pregestational diabetes mellitus, the American College of Obstetricians and Gynecologists recommends antenatal corticosteroids in those with gestational diabetes mellitus at risk for preterm birth. However, this recommendation is based on limited data, only 10.6% of the Antenatal Late Preterm Steroids study sample had gestational diabetes mellitus. There is a paucity of data on the risk of neonatal respiratory and other morbidity in this population.

OBJECTIVE

This study aimed to examine respiratory outcomes in parturients with gestational diabetes mellitus who received antenatal corticosteroids and delivered during the late preterm period vs those who did not.

STUDY DESIGN

This population-based cohort study used the US Vital Statistics dataset between 2016 to 2020. The inclusion criteria were singleton, nonanomalous individuals who delivered between 34.0 to 36.6 weeks with gestational diabetes mellitus and known status of antepartum corticosteroid exposure. The primary outcome, a composite neonatal adverse outcome, included Apgar score <5 at 5 minutes, immediate assisted ventilation, assisted ventilation >6 hours, surfactant use, seizure, or neonatal mortality. The secondary outcome was a composite maternal adverse outcome, including maternal blood transfusion, ruptured uterus, unplanned hysterectomy, and admission to the intensive care unit. Multivariable Poisson regression models were used to estimate adjusted relative risks and 95% confidence intervals. Average annual percent change was calculated to assess changes in rates of corticosteroid exposure over the study period.

RESULTS

Of 19 million births during the study period, 110,197 (0.6%) met the inclusion criteria, and among them, 23,028 (20.9%) individuals with gestational diabetes mellitus received antenatal corticosteroids. The rate of antenatal steroid exposure remained stable over the 5 years (APC=10.7; 95% confidence interval, -5.4 to 29.4). The composite neonatal adverse outcome was significantly higher among those who received corticosteroids than among those who did not (137.1 vs 216.5 per 1000 live births; adjusted relative risk 1.24; 95% confidence interval, 1.20-1.28). Three components of the composite neonatal adverse outcome-immediate assisted ventilation, intubation >6 hours, and surfactant use-were significantly higher with exposure than without. In addition, the composite maternal adverse outcome was significantly higher among those who received corticosteroids (adjusted relative risk, 1.34; 95% confidence interval, 1.18-1.52). Three components of the composite maternal adverse outcome-admission to intensive care unit, blood transfusion, and unplanned hysterectomy-were significantly higher among the exposed group. Subgroup analysis, among large for gestational age, by gestational age, and race and ethnicity, confirm the trend of increased likelihood of adverse outcomes with exposure to corticosteroid.

CONCLUSION

Individuals with gestational diabetes mellitus and antenatal corticosteroid exposure, who delivered in the late preterm, were at higher risk of neonatal and maternal adverse outcomes than those unexposed to corticosteroid.

The impact of volume and neonatal level of care on outcomes of moderate and late preterm infants

OBJECTIVE

Evaluate the relationship of neonatal unit level of care (LOC) and volume with mortality or morbidity in moderate-late preterm (MLP) (32-36 weeks' gestation) infants.

DESIGN

Retrospective cohort study of 650,865 inborn MLP infants in 4976 hospitals-years using 2003-2015 linked administrative data from 4 states. Exposure was combined neonatal LOC and MLP annual volume. The primary outcome was death or morbidity (respiratory distress syndrome, severe intraventricular hemorrhage, necrotizing enterocolitis, sepsis, infection, pneumothorax, extreme length of stay) with components as secondary outcomes. Poisson regression models adjusted for patient characteristics with a random effect for unit were used.

RESULTS

In adjusted models, high-volume level 2 units had a lower risk of the primary outcome compared to low-volume level 3 units (aIRR 0.90 [95% CI 0.83-0.98] vs. aIRR 1.13 [95% CI 1.03-1.24], p < 0.001) CONCLUSION: MLP infants had improved outcomes in high-volume level 2 units compared to low-volume level 3 units in adjusted analysis.

Antenatal steroids and neonatal outcomes in late preterm births with pregestational diabetes

OBJECTIVE

To evaluate if antenatal steroid use was associated with a lower rate of respiratory complications in neonates born late preterm to patients with pregestational diabetes mellitus (PGDM).

METHODS

This was a retrospective cohort study of live, singleton, non-anomalous, late preterm births complicated by PGDM using data from the Centers for Disease Control and National Vital Statistics System from 2017 to 2021. The primary (assisted ventilation use >6 h) and secondary neonatal outcomes (immediate assisted ventilation, Apgar score, neonatal intensive care unit [NICU] admission, and surfactant use) were compared between births that received steroids and those that did not. Multivariable analyses were performed to adjust for differences in demographic and clinical characteristics.

RESULTS

There were 24 323 late preterm births with PGDM, of which 4613 received antenatal steroids and 19 710 did not receive steroids. After adjusting for the differences among the two groups, the need for assisted neonatal ventilation for more than 6 h (adjusted odds ratio [aOR] 1.69, 95% confidence interval [CI] 1.53-1.86), immediate assisted neonatal ventilation (aOR 1.67, 95% CI 1.55-1.80), NICU admission (aOR 1.95, 95% CI 1.81-2.10), and surfactant use (aOR 1.68, 95% CI 1.40-2.02) were higher in the births that received steroids compared with those that did not. These findings did not differ when examining outcomes at each gestational week of delivery between 34 weeks 0 days and 36 weeks 6 days.

CONCLUSIONS

Antenatal steroid use in late preterm births complicated with PGDM was associated with worse immediate respiratory neonatal outcomes. Our findings support current recommendations against the use of steroids in the late preterm period in pregnancies with PGDM.

Regional Variation in Antenatal Late Preterm Steroid Use Following the ALPS Trial

Importance

The publication of the Antenatal Late Preterm Steroids (ALPS) trial in February 2016 demonstrated that antenatal administration of betamethasone in the late preterm period (between 34 to 36 weeks of gestation) for individuals with a high risk of delivery decreased neonatal respiratory morbidity. National estimates have suggested the trial did change obstetric practice, but little is known if the evidence was adopted uniformly or equitably.

Objective

To assess regional variation in the use of late preterm steroids after the publication of the Antenatal Late Preterm Steroids (ALPS) Trial and to understand factors associated with a region's pace of adoption.

Design, Setting, and Participants

This cross-sectional study used US natality data from February 2015 to October 2017 from hospital referral regions (HRRs) within the US. Inclusion criteria included live-born, nonanomalous, singleton, late preterm (34 to 36 completed weeks of gestation) neonates born to individuals without pregestational diabetes. This study was conducted from November 15, 2022, to January 13, 2023.

Main Outcome and Measures

HRRs were categorized as either a slower adopter or faster adopter of antenatal late preterm steroids based on the observed vs expected pace of antenatal steroid adoption in a 1-year period after the trial's dissemination. Patient and regional factors hypothesized a priori to be associated with the uptake of late preterm steroids were compared between faster and slower adopters. Comparisons were made using Student t test or Wilcoxon rank-sum test, as appropriate. A multivariable logistic regression was constructed to identify factors associated with faster adopter status in the postperiod.

Results

There were 666 097 late preterm births in 282 HRRs. The mean (SD) maternal age in HRRs was 27.9 (1.2) years. The median (IQR) percentage of births by race categories in HRRs for patients identifying as American Indian or Alaskan Native was 0.5% (0.2%-1.3%); Asian or Pacific Islander, 3.0% (1.7%-5.3%); Black, 12.9% (5.1%-29.1%); and White, 78.6% (66.6%-87.0%). The median percentage of births in HRRs to patients of Hispanic ethnicity was 11.2% (6.3%-27.4%). In this study, 136 HRRs (48.2%) were classified as faster adopters and 146 (51.8%) were classified as slower adopters. Faster adopters increased their steroid use by 12.1 percentage points (from 5.9% to 18.0%) compared with a 5.5 percentage point increase (from 3.7% to 9.2%) among slower adopters (P < .001). Most examined patient and regional factors were not associated with a region's pace of adoption, with the exception of the regional prevalence of prior preterm birth (adjusted odds ratio [aOR], 2.04 [95% CI, 1.48-2.82]) and the percentage of deliveries at 34 to 35 weeks of gestation (aOR, 0.68 [95% CI, 0.47-0.99]) compared with 36 weeks.

Conclusions and Relevance

In this cross-sectional study, there was widespread geographic variation in the adoption of antenatal steroid administration for late preterm births that largely remained unexplained by population factors. These findings should prompt further investigations to barriers to timely or equitable access to new evidence-based practices and guide future dissemination strategies with the goal of more uniform adoption.

The effect of time interval between antenatal corticosteroid administration and delivery on outcomes in late preterm neonates born to mothers with diabetes: a retrospective cohort study

Objectives

The study aims to investigate whether the time interval between administering antenatal corticosteroids (ACS) and delivery influences the neonatal outcomes in late preterm (LPT) neonates (34 + 0 to 36 + 6 weeks) born to mothers with diabetes.

Study design

This retrospective cohort study included women with any type of diabetes who gave birth between 34 + 0 weeks and 36 + 6 weeks of gestation. Based on the time interval between the first dose of corticosteroid and delivery, the cases were stratified into the following groups: <2, 2-7, and >7 days. Women unexposed to ACS served as the control group. The primary outcomes included the incidence of neonatal hypoglycemia and respiratory distress syndrome/transient tachypnea of the newborn. Multivariate logistic regression was used to assess the relationship between the time interval and neonatal outcomes and adjust for potential confounders.

Results

The study enrolled a total of 636 parturients. Among them, 247 (38.8%) delivered within 2 days after ACS administration, 169 (26.6%) within 2-7 days, and 126 (19.8%) at >7 days. Baseline characteristics such as type of diabetes, methods of glycemic control, preterm premature rupture of membrane, placenta previa, cesarean delivery, indication for delivery, percentage of large for gestational age, birth weight, and HbA1c in the second or third trimester were significantly different among the four groups. The multivariate analysis showed no statistically significant difference in the incidence of primary or secondary neonatal outcomes between the case and control groups.

Conclusions

ACS treatment was not associated with neonatal hypoglycemia and respiratory outcomes in LPT neonates born to diabetic mothers, regardless of the time interval to delivery.

Post Antenatal Late Preterm Steroids trial: interrupted time series analysis of respiratory outcomes in twin and pregestational diabetes

BACKGROUND

The Antenatal Late Preterm Steroids trial found that corticosteroid administration decreased respiratory complications by 20% among late preterm singleton deliveries. After the Antenatal Late Preterm Steroids trial, corticosteroid administration increased by 76% among twin pregnancies and 113% among singleton pregnancies complicated by pregestational diabetes mellitus compared with expected rates based on the pre-Antenatal Late Preterm Steroids trial trend. However, the effect of corticosteroids on twin pregnancies and pregnancies complicated by pregestational diabetes mellitus is not well studied, as the Antenatal Late Preterm Steroids trial excluded twin pregnancies and pregnancies complicated by pregestational diabetes mellitus.

OBJECTIVE

This study aimed to examine the change in the incidence rate of immediate assisted ventilation use and ventilation use for more than 6 hours among 2 populations after the dissemination of the Antenatal Late Preterm Steroids trial at the population level.

STUDY DESIGN

This study was a retrospective analysis of publicly available US birth certificate data. The study period was from August 1, 2014, to April 30, 2018. The dissemination period of the Antenatal Late Preterm Steroids trial was from February 2016 to October 2016. Population-based interrupted time series analyses were performed for 2 target populations: (1) twin pregnancies not complicated by pregestational diabetes mellitus and (2) singleton pregnancies complicated by pregestational diabetes mellitus. For both target populations, analyses were limited to individuals who delivered nonanomalous live neonates between 34 0/7 and 36 6/7 weeks of gestation (vaginal or cesarean delivery). As a sensitivity analysis, a total of 23 placebo tests were conducted before (5 tests) and after (18 tests) the dissemination period.

RESULTS

For the analysis of late preterm twin deliveries, 191,374 individuals without pregestational diabetes mellitus were identified. For the analysis of late preterm singleton pregnancy with pregestational diabetes mellitus, 21,395 individuals were identified. After the dissemination period, the incidence rate of immediate assisted ventilation use for late preterm twin deliveries was significantly lower than the expected value based on the pre-Antenatal Late Preterm Steroids trial trend (11.6% observed vs 13.0% expected; adjusted incidence rate ratio, 0.87; 95% confidence interval, 0.78-0.97). The incidence rate of ventilation use for more than 6 hours among late preterm twin deliveries did not change significantly after the dissemination of the Antenatal Late Preterm Steroids trial. A significant increase in the incidence rate of immediate assisted ventilation use and ventilation use for more than 6 hours was found among singleton pregnancies with pregestational diabetes mellitus. However, the results of placebo tests suggested that the increase in incidence was not necessarily due to the dissemination period of the Antenatal Late Preterm Steroids trial.

CONCLUSION

The dissemination of the Antenatal Late Preterm Steroids trial was associated with decreased incidence of immediate assisted ventilation use, but no change in ventilation use for more than 6 hours, among late preterm twin deliveries in the United States. In contrast, the incidence of neonatal respiratory outcomes among singleton deliveries with pregestational diabetes mellitus did not decrease after the dissemination of the Antenatal Late Preterm Steroids trial.

Antenatal Steroid Exposure Among Term Newborns

This cross-sectional study evaluates the association between dissemination of the Antenatal Late Preterm Steroid trial and changes in steroid exposure among term newborns.