Departments of Obstetrics and Gynecology, University of Alabama at Birmingham, Birmingham, AL.
George Washington University Biostatistics Center, Washington, DC.
Am J Obstet Gynecol. 2018 Sep;219(3):296.e1-296.e8. doi: 10.1016/j.ajog.2018.05.011. Epub 2018 May 22.
Studies of early-term birth after demonstrated fetal lung maturity show that respiratory and other outcomes are worse with early-term birth (37-38 weeks) even after demonstrated fetal lung maturity when compared with full-term birth (39-40 weeks). However, these studies included medically indicated births and are therefore potentially limited by confounding by the indication for delivery. Thus, the increase in adverse outcomes might be due to the indication for early-term birth rather than the early-term birth itself.
We examined the prevalence and risks of adverse neonatal outcomes associated with early-term birth after confirmed fetal lung maturity as compared with full-term birth in the absence of indications for early delivery.
This is a secondary analysis of an observational study of births to 115,502 women in 25 hospitals in the United States from 2008 through 2011. Singleton nonanomalous births at 37-40 weeks with no identifiable indication for delivery were included; early-term births after positive fetal lung maturity testing were compared with full-term births. The primary outcome was a composite of death, ventilator for ≥2 days, continuous positive airway pressure, proven sepsis, pneumonia or meningitis, treated hypoglycemia, hyperbilirubinemia (phototherapy), and 5-minute Apgar <7. Logistic regression and propensity score matching (both 1:1 and 1:2) were used.
In all, 48,137 births met inclusion criteria; the prevalence of fetal lung maturity testing in the absence of medical or obstetric indications for early delivery was 0.52% (n = 249). There were 180 (0.37%) early-term births after confirmed pulmonary maturity and 47,957 full-term births. Women in the former group were more likely to be non-Hispanic white, smoke, have received antenatal steroids, have induction, and have a cesarean. Risks of the composite (16.1% vs 5.4%; adjusted odds ratio, 3.2; 95% confidence interval, 2.1-4.8 from logistic regression) were more frequent with elective early-term birth. Propensity scores matching confirmed the increased primary composite in elective early-term births: adjusted odds ratios, 4.3 (95% confidence interval, 1.8-10.5) for 1:1 and 3.5 (95% confidence interval, 1.8-6.5) for 1:2 matching. Among components of the primary outcome, CPAP use and hyperbilirubinemia requiring phototherapy were significantly increased. Transient tachypnea of the newborn, neonatal intensive care unit admission, and prolonged neonatal intensive care unit stay (>2 days) were also increased with early-term birth.
Even with confirmed pulmonary maturity, early-term birth in the absence of medical or obstetric indications is associated with worse neonatal respiratory and hepatic outcomes compared with full-term birth, suggesting relative immaturity of these organ systems in early-term births.
研究表明，在胎儿肺成熟的前提下，即使是 37-38 周的早期分娩（早产），其呼吸和其他结局也比 39-40 周的足月分娩更差。然而，这些研究纳入了医学指征的分娩，因此可能受到分娩指征的混杂因素的影响。因此，不良结局的增加可能是由于早产本身，而不是早产的指征。
我们研究了在没有早期分娩指征的情况下，确认胎儿肺成熟后的早产与足月分娩相比，新生儿不良结局的发生率和风险。
这是一项对美国 25 家医院 2008 年至 2011 年间 115502 名妇女分娩的观察性研究的二次分析。纳入 37-40 周、无明确分娩指征且无胎儿畸形的单胎非早产儿；将确认胎儿肺成熟后发生的早期分娩与足月分娩进行比较。主要结局是死亡、呼吸机使用≥2 天、持续气道正压通气、证实的败血症、肺炎或脑膜炎、治疗性低血糖、高胆红素血症（光疗）和 5 分钟 Apgar 评分<7。采用 logistic 回归和倾向评分匹配（1:1 和 1:2）。
共有 48137 例符合纳入标准；在没有医学或产科指征的情况下，胎儿肺成熟试验的发生率为 0.52%（n=249）。在确认肺成熟后，有 180 例（0.37%）早期分娩，47957 例足月分娩。前者组的产妇更可能是非西班牙裔白人、吸烟、接受过产前类固醇治疗、引产和剖宫产。复合结局（16.1%比 5.4%；调整优势比，2.1-4.8，logistic 回归）的风险在选择性早期分娩中更高。倾向评分匹配也证实了选择性早期分娩中主要复合结局的增加：调整优势比，1:1 匹配为 4.3（95%可信区间，1.8-10.5），1:2 匹配为 3.5（95%可信区间，1.8-6.5）。主要结局的组成部分中，CPAP 使用和需要光疗的高胆红素血症明显增加。新生儿呼吸窘迫综合征、新生儿重症监护病房入院和新生儿重症监护病房住院时间延长（>2 天）也随着早产而增加。
即使胎儿肺成熟，在没有医学或产科指征的情况下进行早期分娩，与足月分娩相比，新生儿呼吸和肝脏结局也较差，这表明这些器官系统在早期分娩时相对不成熟。
