Home Blood Pressure Levels in Pregnant Women with Chronic Hypertension

Home blood pressure monitoring in the diagnosis and treatment of hypertension in pregnancy: a systematic review and meta-analysis

BACKGROUND

Home blood pressure monitoring is increasingly used for pregnant individuals; however, there are no guidelines on such monitoring in this population. We assessed current practices in the prescription and use of home blood pressure monitoring in pregnancy.

METHODS

We conducted a systematic review and meta-analysis of observational studies and randomized controlled trials (RCTs). We conducted a structured search through the MEDLINE (from 1946), Embase (from 1974) and CENTRAL (from 2018) databases up to Oct. 19, 2020. We included trials comparing office and home blood pressure monitoring in pregnant people. Outcomes included patient education, home blood pressure device, monitoring schedule, adherence, diagnostic thresholds for home blood pressure, and comparison between home and office measurements of blood pressure.

RESULTS

We included in our review 21 articles on 19 individual studies (1 RCT, 18 observational) that assessed home and office blood pressure in pregnant individuals (n = 2843). We observed variation in practice patterns in terms of how home monitoring was prescribed. Eight (42%) of the studies used validated home blood pressure devices. Across all studies, measurements were taken 3 to 36 times per week. Third-trimester home blood pressure corresponding to office blood pressure of 140/90 mm Hg after application of a conversion factor ranged from 118 to 143 mm Hg (systolic) and from 76 to 92 mm Hg (diastolic), depending on the patient population and methodology. Systolic and diastolic blood pressure values measured at home were lower than office values by 4 (95% confidence interval [CI] -6 to -3) mm Hg and 3 (95% CI -4 to -2) mm Hg, respectively.

INTERPRETATION

Many issues related to home blood pressure monitoring in pregnancy are currently unresolved, including technique, monitoring schedule and target values. Future studies should prioritize the use of validated home measuring devices and standardized measurement schedules and should establish treatment targets.

PROSPERO REGISTRATION

CRD42020147352.

Home blood pressure in pregnancy-the upper reference limit

OBJECTIVES

To investigate whether the upper home blood pressure reference limit in healthy pregnant women correspond to 135/85 mmHg as used when diagnosing white coat hypertension outside pregnancy.

METHODS

In this prospective observational study 103 healthy, singleton pregnant women with a mean age of 32 ± 4 (±SD) years and with a median pre-pregnancy body mass index of 21 (interquartile range 20-24) kg/m were included. Home blood pressure was measured with the device Microlife® BP 3A Plus twice daily for three days (18 measurements in total) in addition to routine office blood pressure measurements in early (median 12 (weeks)), mid (20) and late pregnancy (35). Upper blood pressure reference limits were calculated as mean +2 SD.

RESULTS

Office blood pressure versus home blood pressure were 115 ± 11/72 ± 7 versus 103 ± 7/64 ± 5 mmHg in early pregnancy, 112 ± 11/74 ± 7 versus 102 ± 7/63 ± 5 mmHg in mid pregnancy and 118 ± 11/75 ± 8 versus 107 ± 8/66 ± 6 mmHg in late pregnancy. The mean difference between office blood pressure and home blood pressure was 10 mmHg. In late pregnancy, the upper reference limit was 140/91 mmHg for office blood pressure and 123/78 mmHg for home blood pressure with slightly lower values in early and mid pregnancy, respectively.

CONCLUSION

In late pregnancy, the upper home blood pressure reference limit in a population of healthy women was 123/78 mmHg. This value questions the generally proposed level of 135/85 mmHg to define white coat hypertension in pregnancy.

Out-of-office blood pressure measurement for the diagnosis of hypertension in pregnancy: Survey of Canadian Obstetric Medicine and Maternal Fetal Medicine specialists

Background

Multiple hypertension guidelines recommend out-of-office measurements for the diagnosis of hypertension in non-pregnant adults, whereas pregnancy guidelines recommend in-office blood pressure measurements. The objective of our study was to determine how Canadian Obstetric Medicine and Maternal Fetal Medicine specialists measure blood pressure in pregnancy.

Methods

An email survey was sent to 69 Canadian Obstetric Medicine and Maternal Fetal Medicine specialists in academic centers across Canada to explore the practice patterns of blood pressure measurement in pregnant women.

Results

The response rate was 48%. The majority of respondents (63.6%) preferred office blood pressure measurement for diagnosing hypertension, but relied on home blood pressure readings for ongoing monitoring and management of hypertension during pregnancy (59.4%). The preferred method of out-of-office blood pressure measurement was home monitoring; 24-hour ambulatory blood pressure monitoring was not used due to limited availability and cost.

Conclusions

There is wide practice variation in methods of measuring blood pressure among Canadian specialists managing hypertension in pregnancy.

Out of Office Blood Pressure Measurement in Pregnancy and the Postpartum Period

PURPOSE

Hypertensive disorders of pregnancy are increasing in prevalence and associated with significant maternal and perinatal morbidity and mortality.

RECENT FINDINGS

Increased emphasis has been placed recently on the use of out-of-office (i.e., home and ambulatory) blood pressure (BP) monitoring to diagnose and manage hypertension in the general population. Current guidelines offer limited recommendations on the use of out-of-office BP monitoring during pregnancy and postpartum. This review will discuss the recent literature on BP measurement outside of the office and its use for screening, diagnosis, and treatment in pregnancy and postpartum, and will illuminate areas for future research.

Is home blood-pressure monitoring in hypertensive disorders of pregnancy consistent with clinic recordings?

OBJECTIVE

To assess the agreement between home blood-pressure monitoring (HBPM) and blood-pressure measurements in a clinic setting, in a cohort of pregnant women with hypertensive disorders of pregnancy (HDP).

METHODS

This was a cohort study of 147 pregnant women with HDP conducted at St George's Hospital, University of London, London, UK, between 2016 and 2017. Inclusion criteria were chronic hypertension, gestational hypertension or high risk of developing pre-eclampsia, no significant proteinuria and no hematological or biochemical abnormalities. Each included patient was prescribed a personalized schedule of hospital visits and blood-pressure measurements, according to their individual risk as per UK National Institute for Health and Care Excellence guidelines. The blood-pressure measurement at the clinic and the HBPM reading obtained closest to that hospital visit were paired for analysis. Only one pair of measurements was used per patient. Differences between home and clinic blood-pressure measurements were tested using the Wilcoxon signed rank test or paired t-test, and were also assessed visually using Bland-Altman plots. Comparison of the binary outcomes was performed using McNemar's chi-square test. Subgroup analysis was performed in the following gestational-age windows: < 14 weeks, 15-22 weeks, 23-32 weeks and 33-42 weeks' gestation.

RESULTS

A total of 294 blood-pressure measurements from 147 women were included in the analysis. Median systolic HBPM measurements were significantly lower than clinic measurements (132.0 (interquartile range (IQR), 123.0-140.0) mmHg vs 138.0 (IQR, 132.0-146.5) mmHg; P < 0.001). When stratified according to gestational age, systolic blood-pressure measurements obtained at home were significantly lower than those at clinic in all gestational-age periods except 23-32 weeks' gestation (P = 0.057). Median diastolic blood-pressure measurements at home were also significantly lower than those at clinic (85.0 (IQR, 77.0-90.0) mmHg vs 89.0 (IQR, 82.0-94.0) mmHg; P < 0.001). When stratified according to gestational age, diastolic HBPM measurements were significantly lower in the periods 5-14 weeks (P < 0.001), 15-22 weeks (P = 0.008) and 33-42 weeks (P < 0.001), compared with clinic measurements. The incidence of clinically significant systolic and diastolic hypertension based on clinic blood-pressure measurements was four to five times higher than that based on HBPM measurements (P < 0.001 and P = 0.005, respectively).

CONCLUSIONS

Our study shows that, in women with HDP, blood pressure measured at home is lower than that measured in a clinic setting. This is consistent with observations in non-pregnant adults, in whom home and ambulatory monitoring of hypertensive patients is recommended. As such, HBPM has the potential to reduce the number of false-positive diagnoses of severe hypertension and unnecessary medical interventions in women with HDP. This must be carefully weighed against the risk of missing true-positive diagnoses. Prospective studies investigating the use of HBPM in pregnant women are urgently needed to determine the relevant blood-pressure thresholds for HBPM, and interval and frequency of monitoring. Copyright © 2018 ISUOG. Published by John Wiley & Sons Ltd.

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

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.

Blood pressure self-monitoring in pregnancy: examining feasibility in a prospective cohort study

BACKGROUND

Raised blood pressure (BP) affects approximately 10% of pregnancies worldwide, and a high proportion of affected women develop pre-eclampsia. This study aimed to evaluate the feasibility of self-monitoring of BP in pregnancy in women at higher risk of pre-eclampsia.

METHODS

This prospective cohort study of self-monitoring BP in pregnancy was carried out in two hospital trusts in Birmingham and Oxford and thirteen primary care practices in Oxfordshire. Eligible women were those defined by the UK National Institute for Health and Care Excellence (NICE) guidelines as at higher risk of pre-eclampsia. A total of 201 participants were recruited between 12 and 16 weeks of pregnancy and were asked to take two BP readings twice daily three times a week through their pregnancy. Primary outcomes were recruitment, retention and persistence of self-monitoring. Study recruitment and retention were analysed with descriptive statistics. Survival analysis was used to evaluate the persistence of self-monitoring and the performance of self-monitoring in the early detection of gestational hypertension, compared to clinic BP monitoring. Secondary outcomes were the mean clinic and self-monitored BP readings and the performance of self-monitoring in the detection of gestational hypertension and pre-eclampsia compared to clinic BP.

RESULTS

Of 201 women recruited, 161 (80%) remained in the study at 36 weeks or to the end of their pregnancy, 162 (81%) provided any home readings suitable for analysis, 148 (74%) continued to self-monitor at 20 weeks and 107 (66%) at 36 weeks. Self-monitored readings were similar in value to contemporaneous matched clinic readings for both systolic and diastolic BP. Of the 23 who developed gestational hypertension or pre-eclampsia and self-monitored, 9 (39%) had a raised home BP prior to a raised clinic BP.

CONCLUSIONS

Self-monitoring of BP in pregnancy is feasible and has potential to be useful in the early detection of gestational hypertensive disorders but maintaining self-monitoring throughout pregnancy requires support and probably enhanced training.

Provisional criteria for the diagnosis of hypertension in pregnancy using home blood pressure measurements

Most guidelines for the management of hypertension define it as a home blood pressure (HBP) value >135/85 mm Hg. However, there is no reference HBP value to diagnose hypertension in pregnant women. Therefore, in this study, we analyzed HBP measurements of pregnant women to determine whether it is appropriate to use the criteria for non-pregnant subjects for pregnant women. The participants of this study were 100 singleton pregnant women who visited our hospital between September 2013 and September 2016. We lent sphygmomanometers to the patients so they could measure their BP at home twice daily, and we measured their clinical BP when they visited the hospital. Six patients developed hypertensive disorders in pregnancy, whereas there were 63 women without hypertension or other complications that may affect BP. In the normotensive pregnant women, HBP values significantly correlated with the clinical BP values. HBP values equivalent to a clinical BP of 140/90 mm Hg, determined using the standard major axis method, were 120.8/83.5 mm Hg, 126.0/85.2 mm Hg and 136.3/89.3 mm Hg in the first, second and third trimesters, respectively. In normotensive pregnant women, HBP levels that indicate a risk of hypertensive disorder in pregnancy may be lower than 135/85 mm Hg before 28 weeks of gestation.

Diagnosis, evaluation, and management of the hypertensive disorders of pregnancy

OBJECTIVE

This guideline summarizes the quality of the evidence to date and provides a reasonable approach to the diagnosis, evaluation and treatment of the hypertensive disorders of pregnancy (HDP).

EVIDENCE

The literature reviewed included the previous Society of Obstetricians and Gynaecologists of Canada (SOGC) HDP guidelines from 2008 and their reference lists, and an update from 2006. Medline, Cochrane Database of Systematic Reviews (CDSR), Cochrane Central Registry of Controlled Trials (CCRCT) and Database of Abstracts and Reviews of Effects (DARE) were searched for literature published between January 2006 and March 2012. Articles were restricted to those published in French or English. Recommendations were evaluated using the criteria of the Canadian Task Force on Preventive Health Care and GRADE.