Home blood pressure monitoring in higher risk pregnancy does not improve hypertension detection or control compared with usual care, two UK randomised controlled trials found.

The BUMP 1 and 2 studies were the largest randomised controlled trials of blood pressure self-monitoring to date in pregnancy, the authors wrote in JAMA, and were designed to discover whether home monitoring could help early identification of hypertension in pregnancy (BUMP 1) or control of blood pressure for women with pregnancy hypertension (BUMP 2).

In the BUMP 1 trial, which recruited 2,441 pregnant women at higher risk of preeclampsia at a mean of 20-weeks gestation, researchers found no significant difference in the time between randomisation and clinic-based detection of hypertension between the group who self-monitored blood pressure with telemonitoring plus usual care (104 days) and the group who had usual care alone (106 days).

There were no significant differences in either maternal or perinatal outcomes or serious adverse events, they added.

In the BUMP 2 trial, which enrolled 850 pregnant individuals with chronic hypertension or gestational hypertension, researchers found compared with usual care alone, self-monitoring plus telemonitoring resulted in an adjusted mean difference in clinic-based systolic blood pressure of 0.03 mm Hg for chronic hypertension and -0.03 mm Hg for gestational hypertension, neither of which were a statistically significant difference.

Researchers noted that almost 25% of participants recorded only normal blood pressure at home, despite elevated clinic readings, which suggested a white coat effect that might have diluted any effect of self-monitoring on blood pressure control as measured in the clinic.

In a linked editorial in JAMA, Dr Laura E Riley, of the Department of Obstetrics and Gynecology at Weill Cornell Medicine, New York, and colleagues, said individuals at risk of a hypertensive disorder of pregnancy or gestational or chronic hypertension could not be treated with a single approach.

More research was needed to see whether individuals at the highest risk of preeclampsia may benefit from home monitoring, they said, as well as the effects on perinatal outcomes for those with higher blood pressures.

They also cautioned there were issues around equitable access to self-monitoring, noting it required a reliable BP cuff, a smartphone to record data in an app and the ability to communicate with the clinician providing prenatal care.

Co-author Professor Richard McManus, practising GP and Professor of Primary Care at the Nuffield Department of Primary Care Health Sciences at the University of Oxford, said the studies had a broad inclusion criteria and good representation across different ethnicities and levels of social deprivation across England.

‘While we found that self-monitoring made no difference to timing of diagnosis or control of high blood pressure, it does appear to be safe and well tolerated,’ he said in a statement.

Co-author Professor Lucy Chappel, Professor of Obstetrics at King’s College London, said

investigators wanted to consider how to develop the interventions further so they could understand how we can improve health outcomes for women with pregnancy hypertension.

In the meantime, women and pregnant people who wish to self-monitor can continue to do this and are advised to share their readings with their midwives/other clinicians,” she said in a statement.

The National Institute for Health and Care Research funded the trials.