Effect of Self-monitoring of Blood Pressure on Diagnosis of Hypertension During Higher-Risk Pregnancy

Importance: Inadequate management of elevated blood pressure (BP) is a significant contributing factor to maternal deaths. Self-monitoring of BP in the general population has been shown to improve the diagnosis and management of hypertension; however, little is known about its use in pregnancy. Objective: To determine whether self-monitoring of BP in higher-risk pregnancies leads to earlier detection of pregnancy hypertension. Design, Setting, and Participants: Unblinded, randomized clinical trial that included 2441 pregnant individuals at higher risk of preeclampsia and recruited at a mean of 20 weeks' gestation from 15 hospital maternity units in England between November 2018 and October 2019. Final follow-up was completed in April 2020. Interventions: Participating individuals were randomized to either BP self-monitoring with telemonitoring (n = 1223) plus usual care or usual antenatal care alone (n = 1218) without access to telemonitored BP. Main Outcomes and Measures: The primary outcome was time to first recorded hypertension measured by a health care professional. Results: Among 2441 participants who were randomized (mean SD age, 33 5.6 years; mean gestation, 20 1.6 weeks), 2346 (96%) completed the trial. The time from randomization to clinic recording of hypertension was not significantly different between individuals in the self-monitoring group (mean SD, 104.3 32.6 days) vs in the usual care group (mean SD, 106.2 32.0 days) (mean difference, -1.6 days 95% CI, -8.1 to 4.9; P = .64). Eighteen serious adverse events were reported during the trial with none judged as related to the intervention (12 1% in the self-monitoring group vs 6 0.5% in the usual care group). Conclusions and Relevance: Among pregnant individuals at higher risk of preeclampsia, blood pressure self-monitoring with telemonitoring, compared with usual care, did not lead to significantly earlier clinic-based detection of hypertension. Trial Registration: ClinicalTrials.gov Identifier: NCT03334149.