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. 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. 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. 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. 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.

中文翻译：

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单剂量和标准剂量的产前皮质类固醇对于晚期早产新生儿结局的等效性：二次分析的见解

最近用产前皮质类固醇治疗有晚期早产风险的个体的范式转变需要对单剂量的效果进行评估。比较单剂量产前皮质类固醇与安慰剂后早产晚期（34.0-36.6 周）出生的新生儿的结局。我们对产前晚期早产类固醇试验进行了二次分析。所有参加母体试验、仅接受单剂产前皮质类固醇或安慰剂并在 24 小时内分娩的个体均被纳入。主要结局是 72 小时呼吸支持的综合结果，包括持续气道正压或高流量鼻插管≥2 小时、吸入分数≥30% 的吸氧≥4 小时或机械通气。在家长试验的 2831 人中，1083 人（38.3%）符合纳入标准；其中，539 人（49.8%）接受单剂产前皮质类固醇，544 人（50.2%）接受单剂安慰剂。安慰剂组和产前皮质类固醇组具有相似的人口统计学和临床​​特征。主要呼吸系统结局发生率（调整后风险比，1.12；95%置信区间，0.85-1.47）或呼吸窘迫综合征发生率（调整后风险比，1.47；95%置信区间，0.95-1.47）没有差异。 2.26）在接受单次产前皮质类固醇剂量和安慰剂的患者之间进行比较。通过以 12 小时为增量的随机分娩间隔进行的探索性分层也显示与较低的主要呼吸系统结局率没有关联。在晚期早产妊娠的个体中，接受产前皮质类固醇治疗并在第二次给药前分娩的个体中，与安慰剂相比，新生儿呼吸道疾病的发病率没有差异。然而，这项研究并不能检测治疗效果。