(1067) Trends in Adverse Pregnancy Outcomes Following Publication of the CHAP Trial

Objective:
In 2022, the CHAP (Chronic Hypertension and Pregnancy) trial was published demonstrating active treatment of mild chronic hypertension (CHTN) during pregnancy to a goal of < 140/90 reduces a composite of adverse pregnancy outcomes (APOs) < 35 weeks. We assess national trends in these APOs since CHAP’s publication.

Study Design:
This retrospective cohort study included all individuals with CHTN and birth hospitalizations from 1/2020-6/2025 identified from a national data network aggregating records from > 1,600 hospitals. The primary outcome was a composite of APOs including PTB < 35 weeks, superimposed preeclampsia with severe features, placental abruption/antepartum hemorrhage, and stillbirth or neonatal demise. Outcomes were compared between pre-CHAP (1/2020-4/2022) and post-CHAP (1/2023-6/2025), excluding 5/2022-12/2022 as a washout period following CHAP publication. Chi-squared tests assessed outcome differences by period. Unadjusted and adjusted logistic regression models evaluated the effect of the intervention period, adjusting for maternal race, payor, pre-delivery body mass index, multiparity, pregestational diabetes, and smoking. Sensitivity analyses were stratified by whether individuals delivered in one or both periods.

Results:
During the study period, 322,434 births met inclusion criteria with 123,820 (38.7%) occurring in the pre-CHAP and 197,614 (61.3%) in the post-CHAP period. Post-CHAP births had a higher prevalence of composite APOs (18.8% vs. 17.9%, p< 0.01) compared to pre-CHAP births. PTB < 35 weeks decreased significantly from 10.3% to 9.9%, while the other individual components increased significantly (Figure 1). After adjustment, births in the post-CHAP period had a 6% higher likelihood of composite APOs (aOR 1.06, 95% CI: 1.04, 1.08) compared to those in the pre-CHAP period (Table 1). Sensitivity analyses noted similar findings.

Conclusion:
In this national analysis, the incidence of the CHAP APO composite increased from pre- to post-CHAP but PTB < 35 weeks decreased. Further investigation may elucidate opportunities for achieving the outcomes of CHAP in a real-world setting.