Self-monitoring blood pressure during pregnancy with hypertension

Katherine Tucker, PhD

“We know that self-monitoring of blood pressure is effective at detecting and lowering blood pressure in the general population, but little was known about its usefulness in pregnancy,” said co-author Katherine Tucker, PhD, senior researcher at the University of Oxford in the United Kingdom.

Tucker noted that roughly 1 in 10 pregnant women will develop high blood pressure, and about half of those women will go on to develop preeclampsia, which puts both mother and baby at risk.

“High blood pressure in pregnancy is relatively common and, potentially, very serious. Self-monitoring of BP might help with both detection and management of such hypertension,” Tucker said.

The unblinded, randomized BUMP 2 (Blood Pressure Monitoring in High-Risk Pregnancy to Improve the Detection and Monitoring of Hypertension 2) clinical trial recruited 850 women with chronic hypertension at up to 37 weeks’ gestation, or with gestational hypertension between 20 and 37 weeks’ gestation from 15 hospital maternity units in England from November 2018 to September 2019. Final follow-up was in May 2020.

Participants were randomized to either self-monitor their blood pressure with a validated monitor and a secure telemonitoring system in addition to usual care (n = 430) or to usual care alone (n = 420).

The primary maternal outcome was the difference in mean systolic blood pressure recorded by health care professionals between randomization and birth.

In the chronic hypertension cohort, researchers found no statistically significant difference in mean systolic blood pressure between the self-monitoring group and the usual care group: 133.8 mm Hg vs. 133.6 mm Hg, respectively; adjusted mean difference = 0.03 mm Hg; 95% confidence interval (CI): −1.73 to 1.79.

In the gestational hypertension cohort, there was no significant difference in mean systolic blood pressure: 137.6 mm Hg vs. 137.2 mm Hg, respectively; adjusted mean difference = −0.03 mm Hg; 95% CI: −2.29 to 2.24.

There were 8 serious adverse events in the self-monitoring group (4 in each of the 2 cohorts) and 3 in the usual care group (2 in the chronic hypertension cohort and 1 in the gestational hypertension cohort).

“We were disappointed that we did not see any improvements in blood pressure control, between women who self-monitored using the BUMP app and those that did not,” Tucker told Contemporary OB/GYN®. “But perhaps this is not surprising. Changes to care pathways are not straightforward. We know that in the general population, self-monitoring of blood pressure is more effective when combined with further intervention, such as education, self-management of medication or clinical checks.”

The findings suggest that self-monitoring of blood pressure in pregnancy is safe and well tolerated, which Tucker said should reassure clinical teams going forward. “Therefore, pregnant women who wish to self-monitor can do so, and are advised to share their readings with their midwives or other clinicians,” she said.

The linked BUMP1 randomized clinical trial found that over half of the higher-risk women who self-monitored their blood pressure recorded a raised blood pressure reading at home, “on average around 1 month prior to their clinic diagnosis,” Tucker said. “While this was not reflected in the overall results of our current analysis, it provides a future direction for our research.”

The authors plan to further research and develop the pathways and support around self-monitoring of blood pressure, so they can understand how to improve health outcomes for women with pregnancy hypertension.

Reference

1. Chappell LC, Tucker KL, Galal U, et al. Effect of self-monitoring of blood pressure on blood pressure control in pregnant individuals with chronic or gestational hypertension: the BUMP 2 randomized clinical trial. JAMA. Published online May 3, 2022. doi:10.1001/jama.2022.4726