Uncontrolled and masked uncontrolled blood pressure in treated pregnant women with chronic hypertension and risk for preeclampsia/eclampsia.

To analyze the relationship between the level of BP achieved with treatment and the risk for development of preeclampsia/eclampsia (PE), we conducted a historical cohort study on 149 consecutive pregnant women with treated chronic hypertension, evaluated between January 1, 2016, and November 31, 2022. According to office BP readings and ambulatory blood pressure monitoring (ABPM) performed after 20 weeks of gestation, the cohort was classified in controlled hypertension, white-coat uncontrolled hypertension, masked uncontrolled hypertension and sustained hypertension. Risks for the development of PE were estimated using logistic regression. One hundred and twenty-four pregnant women with a control BP evaluation were included in this analysis. The rates of PE were 19.4%, 27.3%, 44.8% and 47.1% for controlled, white-coat uncontrolled, masked uncontrolled and sustained uncontrolled hypertension, respectively. Compared with women with controlled hypertension, the relative risk for PE increased markedly in women with sustained uncontrolled (OR 3.69, 95% CI, 1.19-11.45) and masked uncontrolled (OR 3.38, 95% CI, 1.30-11.45) hypertension, but not in those with white-coat uncontrolled (OR 1.56 95% CI, 0.36-6.70); adjustment for covariates did not modify the results. Each mmHg higher of systolic and diastolic daytime ABPM increased the relative risk for PE ~4% and ~5%, respectively. Each mmHg higher of systolic and diastolic nocturnal BP increased the risk ~5% and ~6%, respectively. When these risks were adjusted for ABPM values in opposite periods of the day, only nocturnal ABPM remained as a significant predictor. In conclusion, masked uncontrolled hypertension implies a substantial risk for the development of PE, comparable to those of sustained uncontrolled. The presence of nocturnal hypertension seems important.