Division of Epidemiology, UC Berkeley School of Public Health, Berkeley, CA; Stanford University School of Medicine, Stanford, CA.
Johns Hopkins Bloomberg School of Public Health, Department of Population, Family and Reproductive Health, Baltimore, MD.
Ann Epidemiol. 2020 Sep;49:8-12. doi: 10.1016/j.annepidem.2020.07.002. Epub 2020 Jul 8.
We use data from California, where 13% of US births occur, to address two questions arising from efforts in the first decade of this century to avoid stillbirths before 25 6/7 weeks of gestation (i.e., in the periviable period). First, did stillbirths decline in the first decade of this century? Second, if stillbirths did decline, did periviable live births increase simultaneously? Answering these questions is important given that periviable infants represent less than 1% of live births but account for roughly 40% of infant mortality and 20% of hospital-based obstetric costs in the United States.
We constructed 240 monthly conception cohorts, starting with that conceived in January 1991, from 9,880,536 singleton pregnancies that reached the 20 0/7 week of gestation. We used time-series design and Box-Jenkins methods that address confounding by autocorrelation, including secular trends and seasonality to answer our questions.
We detected a downward shift in stillbirths in April 2007 that coincided with an upward shift in periviable live births.
Our findings imply that, since 2007, fewer Californians than expected from history and from the size of conception cohorts reaching 20 0/7 weeks of gestation have had to contend with the sequelae of stillbirths, but more than expected likely have had to contend with those of periviable births.
我们利用来自加利福尼亚州的数据（该州占美国出生人口的 13%）来回答本世纪初避免在 25 6/7 周之前（即围产前期）发生死产的努力中出现的两个问题。首先，本世纪初死产是否有所下降？其次，如果死产确实有所下降，围产前期的活产是否同时增加？鉴于围产前期婴儿占活产儿的比例不到 1%，但在美国占婴儿死亡率的 40%左右，占产科住院费用的 20%左右，因此回答这些问题很重要。
我们从 9880536 例达到 20 0/7 周妊娠的单胎妊娠中构建了 240 个每月受孕队列，从 1991 年 1 月受孕的队列开始。我们使用时间序列设计和 Box-Jenkins 方法来回答我们的问题，这些方法可以解决自相关引起的混杂，包括长期趋势和季节性。
我们发现，2007 年 4 月死产出现了下降趋势，同期围产前期活产出现了上升趋势。
我们的研究结果表明，自 2007 年以来，加利福尼亚州的死产后果比预期的要少，因为从历史和达到 20 0/7 周妊娠的受孕队列的规模来看，有更多的人可能不得不应对围产前期出生的后果。
