妊娠中のコルチコステロイドと脳性麻痺のリスク：回帰不連続性研究

To use a natural experiment to investigate the effect of antenatal corticosteroids on the risk of cerebral palsy.

We included singleton livebirths with a maternal admission for delivery from 31+0 through 36+6 weeks of gestation, in British Columbia, Canada, between 2000-2015. Guidelines recommended antenatal corticosteroids through 33+6 weeks, and we estimated the effect of the corresponding sharp drop in the proportion treated at 34+0 weeks on the risk of a composite of death before age 2 or cerebral palsy. We defined cerebral palsy using diagnostic codes in hospital and physician-billing records through age five years and corrected for misclassification using external estimates of the sensitivity and specificity. We used logistic regression to estimate marginal effects at 34+0 weeks.

There were 20,009 children in our study sample. The crude and misclassification-corrected risks of cerebral palsy were 6.2 and 5.6 per 1,000, respectively. The risk of death before age 2 or cerebral palsy declined with increasing gestational age at maternal admission for delivery, but we found no convincing evidence of an abrupt change just before vs just after 34+0 weeks (risk ratio: 0.98, 95% CI: 0.50 to 1.98). Results were similar using a composite outcome of in-hospital newborn death or cerebral palsy, and cerebral palsy alone.

We did not find evidence that the lower likelihood of being treated with antenatal corticosteroid at 34+0 weeks affected the risk of cerebral palsy, but the estimates were imprecise and compatible with benefits or harms.