(209) The effect of the ARRIVE trial on hypertensive disease of pregnancy rates among low-risk primigravidas

The ARRIVE trial suggested that 39^th week induction in low-risk nulliparas would lower the rate of gestational hypertension and preeclampsia (i.e. hypertensive disorders of pregnancy (HDP)). Recent studies showed that obstetrical practices in this low-risk group changed to reflect a nationwide response to its findings. Here we sought to determine if HDP rate also decreased over this time in this low-risk group

Study Design:

We conducted a population-based, cohort study of low-risk nulliparous patients delivered between 39+0 and 41+6 weeks using data from the US Natality database. Pre-ARRIVE group was births between Jan-2015 to Dec-2018 and post-ARRIVE group was births between Jan-2019 to Dec-2020. We compared the mean HDP rate in the two groups among women induced and delivered by 39^th week using chi-square test. A logistic regression model was used to project the HDP rate over time based on the pre-ARRIVE rate. Wald confidence intervals were used to compare the predicted vs the actual rates of HDP

Results:

Of the 2,120,044 births in the pre-ARRIVE group, 244,665 (11.5%) were 39^th week inductions and of the 987,494 in the post-ARRIVE group, 157,494 (16%) were 39^th week inductions. The overall HDP rate for all deliveries, deliveries among 39^th week inductions, and all other deliveries (excluding 39^th week inductions) is summarized in Figure 1. The mean HDP rate in the post-ARRIVE group was significantly lower compared to pre-ARRIVE group (p < 0.001). A projection of the HDP rate based on pre-ARRIVE trends showed a significant change in the HDP rate among the 39^th week induction group. But, the trend of HDP in the total cohort continued to rise

Conclusion:

There was a decrease in HDP among 39^th week inductions in the years after the ARRIVE trial. Despite a significant decline in the HDP rate in this low-risk group, the overall HDP rate continued to increase. Thus, the 39^th week induction group in the post-ARRIVE years may have included a higher percentage of patients induced who may have been at low risk for HDP, whereas in the pre-ARRIVE group many may have more inductions and deliveries because of HDP