How Do Home and Clinic Blood Pressure Readings Compare in Pregnancy?

Abstract

Hypertensive disorders during pregnancy result in substantial maternal morbidity and are a leading cause of maternal deaths worldwide. Self-monitoring of blood pressure (BP) might improve the detection and management of hypertensive disorders of pregnancy, but few data are available, including regarding appropriate thresholds. This systematic review and individual patient data analysis aimed to assess the current evidence on differences between clinic and self-monitored BP through pregnancy. MEDLINE and 10 other electronic databases were searched for articles published up to and including July 2016 using a strategy designed to capture all the literature on self-monitoring of BP during pregnancy. Investigators of included studies were contacted requesting individual patient data: self-monitored and clinic BP and demographic data. Twenty-one studies that utilized self-monitoring of BP during pregnancy were identified. Individual patient data from self-monitored and clinic readings were available from 7 plus 1 unpublished articles (8 studies; n=758) and 2 further studies published summary data. Analysis revealed a mean self-monitoring clinic difference of ≤1.2 mm Hg systolic BP throughout pregnancy although there was significant heterogeneity (difference in means, I² >80% throughout pregnancy). Although the overall population difference was small, levels of white coat hypertension were high, particularly toward the end of pregnancy. The available literature includes no evidence of a systematic difference between self and clinic readings, suggesting that appropriate treatment and diagnostic thresholds for self-monitoring during pregnancy would be equivalent to standard clinic thresholds.

Keywords: blood pressure; hypertension; pre-eclampsia; pregnancy; white coat hypertension.

Figure 1.

Flow diagram of the systematic review. Studies included in the analysis of clinic and self-monitored blood pressure during pregnancy.

Figure 2.

Comparison of clinic and self-monitored systolic blood pressure (BP). Forest plots were constructed to examine the difference in mean BP (clinic–home) by the type of monitoring and study group. Data were analyzed as continuous variables and presented here in mm Hg, plotted by gestational stage. CI indicates confidence interval.

Figure 3.

Agreement between clinic and self-monitored blood pressure (BP) readings during pregnancy. Bland-Altman plots were used to examine the influence of mean BP on the clinic−self difference. The mean clinic and self-monitored readings were plotted against clinic−self monitored readings (complete cases). At 5 to 14 wk, there was a mean difference of 1.403, 6.8% (17 of 250) readings were outside limits of agreement, and 95% limits of agreement were −16.943, 19.750. At 15 to 22 wk, a mean difference of 1.550 was observed, 6.26% (27 of 431) readings were outside limits of agreement, and the 95% limits of agreement were −18.576, 21.677. At 23 to 32 wk gestation, there was a mean difference of 1.067, 4.82% (25 of 519) readings were outside limits of agreement, and the 95% limits of agreement were −20.736, 22.871. At 33 to 42 wk gestation, there was a mean difference of 1.494, 4.66% (22 of 472) readings were outside limits of agreement, and 95% limits of agreement were −19.429, 22.417. Diastolic plots are shown in Figure S6.