PDF(Pubmed)
Abstract：
Objective: To examine how changes in induction of labor (IOL) and cesarean deliveries between 1990 and 2017 affected gestational age distributions of births in the United States. Materials and Methods: Singleton first births were drawn from the National Vital Statistics System Birth Data for years 1990-2017. Separate analytic samples were created (1) by maternal race/ethnicity (Hispanic, non-Hispanic Black, non-Hispanic Asian, and non-Hispanic white), (2) by maternal age (15-19, 20-24, 25-29, 30-34, 35-39, 40-49), (3) by U.S. states, and (4) for women at low risk for obstetric interventions (e.g., age 20-34, no hypertension, no diabetes, no tobacco use). Gestational age was measured in weeks, and obstetric intervention status was measured as: (1) no IOL, vaginal delivery; (2) no IOL, cesarean delivery; and (3) IOL, all deliveries. The joint probabilities of birth at each gestational week by obstetric intervention status for years 1990-1991, 1998-1999, 2007-2008, and 2016-2017 were estimated. Results: Between 1990 and 2017, the percent of singleton first births occurring between 37 and 39 weeks of gestation increased from 38.5% to 49.5%. The changes were driven by increases in IOL and a shift in the use of cesarean deliveries toward earlier gestations. The changes were observed among all racial/ethnic groups and all maternal ages, and across all U.S. states. The same changes were also observed among U.S. women at low risk for interventions. Conclusion: Changes in gestational age distributions of U.S. births and their underlying causes are likely national-level phenomena and do not appear to be responding to increases in maternal risk for interventions.
摘要：
目的：研究1990年至2017年间引产（IOL）和剖宫产分娩的变化如何影响美国新生儿的胎龄分布。材料和方法：单胎第一胎来自1990-2017年的国家生命统计系统出生数据。单独创建分析样本(1)按母亲种族/种族(西班牙裔，非西班牙裔黑人,非西班牙裔亚洲人，和非西班牙裔白人)，（2）按产妇年龄（15-19、20-24、25-29、30-34、35-39、40-49），（3）美国各州，和(4)产科干预风险较低的妇女(例如，20-34岁无高血压,没有糖尿病,不使用烟草)。以周为单位测量孕龄，产科干预状态测量为：（1）无人工晶状体，阴道分娩;(2)无人工晶状体,剖宫产；和（3）人工晶状体，所有交付。根据1990-1991年，1998-1999年，2007-2008年和2016-2017年的产科干预状况，估计了每个孕周的联合出生概率。结果：在1990年至2017年之间，在妊娠37至39周之间发生的单胎第一胎的百分比从38.5％增加到49.5％。这些变化是由IOL的增加和剖宫产的使用向妊娠早期的转变所驱动的。在所有种族/族裔群体和所有母亲年龄中观察到了变化，在美国所有州。在低干预风险的美国女性中也观察到了同样的变化。结论：美国新生儿胎龄分布的变化及其根本原因很可能是国家一级的现象，似乎并不能应对孕产妇干预风险的增加。
