Daily Serial Hemodynamic Data During Pregnancy and Seasonal Variation: The BOSHI Study

A multicenter prospective study of home blood pressure measurement (HBPM) during pregnancy in Japanese women

In the near future, hypertensive disorders of pregnancy (HDP) have been diagnosed by home blood pressure monitoring (HBPM) instead of clinic BP monitoring. A multicenter study of HBPM was performed in pregnant Japanese women in the non-high risk group for HDP. Participants were women (n = 218), uncomplicated pregnancy who self-measured and recorded their HBP daily. Twelve women developed HDP. HBP was appropriate (100 mmHg in systole and 63 mmHg in diastole), bottoming out at 17 to 21 weeks of gestation. It increased after 24 weeks of gestation and returned to non-pregnant levels by 4 weeks of postpartum. The upper limit of normal HBP was defined as the mean value +3 SD for systolic and mean +2 SD for diastolic with reference to the criteria for non-pregnant women. Using the polynomial equation, the hypertensive cut-off of systolic HBP was 125 mmHg at 15 weeks and 132 mmHg at 30 weeks of gestation, while it for diastolic HBP was 79 mmHg at 15 weeks and 81 mmHg at 30 weeks of gestation. Systolic HBP in women who developed HDP was higher after 24 weeks of gestation, and diastolic HBP was higher during most of the pregnancy compared to normal pregnancy. When the variability of individual HBP in women developed HDP compared to normal pregnant women was examined using the coefficient of variation (CV), the CV was lower in HDP before the onset of HDP. HBPM can be used not only for HDP determination, but also for early detection of HDP.

Epidemiological studies regarding hypertensive disorders of pregnancy: A review

A hypertensive disorder of pregnancy (HDP) is defined as hypertension emerging after 20 weeks of gestation and resolving up to 12 weeks post-partum, and occurs in about 5% of all pregnancies. Complications associated with HDP have poor prognoses, and maternal deaths attributable to HDP are predicted to exceed 70 000 per year worldwide. Understanding the pathogenesis and risk factors of hypertensive disorders of pregnancy is important, and they are often investigated in observational studies. Given that therapeutic interventions cannot be controlled in observed studies, it is necessary to interpret which factors correspond to exposure and which factors correspond to confounding and intermediate factors in each study. From the Babies and their parents' longitudinal observation in the Suzuki Memorial Hospital on Intrauterine period study, blood pressure in early pregnancy was not only predictive of a child's birthweight, but the trajectory was also associated with the birthweight. From the larger-scale birth cohort studies currently conducted in Japan will provide the novel potential risk factors of hypertensive disorders of pregnancy and preventive strategies of them. In Japan, observational or intervention studies are just beginning to emerge. The continuation of both a distinctive cohort and a large cohort is needed, and the development of good quality intervention trials based on the results of observational studies is important.

Blood pressure measurement by oscillometric and auscultatory methods in normotensive pregnant women

OBJECTIVE

to compare blood pressure values obtained by auscultatory and oscillometric methods in different gestational periods, considering cuff width.

METHOD

it is a cross-sectional and quasi-experimental study approved by the Research Ethics Committee. The sample consisted of 108 low-risk pregnant women. Blood pressure measurements were performed in gestational periods of 10-14, 19-22 and 27-30 weeks.

RESULTS

The oscillometric device presented values similar to the auscultatory method in systolic blood pressure, but overestimated diastolic blood pressure. Underestimation of blood pressure occurred when using the standard width cuff rather than the correct width cuff in both measuring methods.

CONCLUSION

Verification of brachial circumference and use of adequate cuffs in both methods are indispensable to obtain reliable blood pressure values in pregnant women. We recommend performance of additional studies to evaluate diastolic blood pressure overestimation by the Microlife 3BTO-A.

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.

Differences in home blood pressure and pulse rates between singleton and twin pregnancies

Objectives

To evaluate home blood pressure (HBP) measurements during pregnancy and postpartum and investigate differences between singleton and twin pregnancies.

Methods

This prospective study involved normotensive, pregnant women who were planning to give birth at Saitama Medical Centre, Saitama, Japan between September 2013 and March 2017. HBP and pulse rate were measured twice daily and clinical blood pressure values were determined from patient records.

Results

HBP values were available from 101 participants; 69 women with singleton and 32 women with twin pregnancies. Systolic BP was statistically significantly higher in twin pregnancies from 23 weeks of gestation until 8 weeks after delivery compared with singleton pregnancies. Pulse rate was also statistically significantly higher between 11 and 30 weeks gestation in women with twin pregnancies compared with those with singleton pregnancies.

Conclusions

BP monitoring is important in the management of twin pregnancies, especially during the later gestational weeks and postpartum period and HBP would facilitate this monitoring.

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.

Maternal clinic and home blood pressure measurements during pregnancy and infant birth weight: the BOSHI study

This prospective cohort study compared measurements of maternal home blood pressure (HBP) with clinic blood pressure (CBP) before 20 weeks' gestation to determine associations with the risk of delivering a lower birth weight infant. A total of 605 Japanese women were included. Exposures were initial CBP, made between 10 weeks 0 days and 19 weeks 0 days, and HBP for comparison made within 1 week of CBP. Outcome was infant's birth weight, categorized and ranked as follows: ⩾3500 g, 3000-3499 g, 2500-2999 g and <2500 g. The proportional odds model with possible confounding factors was applied to compare the associations between CBP and HBP on infant birth weight. When both CBP and HBP were included simultaneously, the adjusted odds ratios (ORs) per 1 standard deviation (1s.d.) increase in clinic and home diastolic BP (DBP) were 1.06 (95% confidence interval (CI): 0.87-1.30) and 1.28 (95% CI: 1.04-1.58), respectively. The adjusted ORs per 1s.d. increase in clinic and home mean arterial pressure (MAP) were 1.02 (95% CI: 0.83-1.24) and 1.29 (95% CI: 1.04-1.59), respectively. Systolic BP measurement was not associated with infant birth weight. In conclusion, high maternal home DBP and MAP before 20 weeks' gestation was associated with a higher risk of lower infant birth weight than clinic DBP and MAP. Therefore, in addition to CBP, it may be worth having pregnant women measure HBP to determine the risk of lower infant birth weight.

Are Meteorological Conditions within the First Trimester of Pregnancy Associated with the Risk of Severe Pre-Eclampsia?

BACKGROUND

Severe pre-eclampsia (SPE) is the second cause of maternal death in developed countries. The literature suggests different risk factors for early- and late-onset pre-eclampsia. SPE is usually related to the early-onset type. Pre-eclampsia rate exhibits seasonal variation. However, the weather-SPE association is still unknown. We examined the associations between maternal exposure to meteorological parameters after conception and SPE.

METHODS

From 2008 to 2011, all deliveries of women living in the Yvelines area, France, have been prospectively registered. Meteorological measurements from weather stations scattered inside Yvelines were averaged on two exposure windows: early-pregnancy (30 days after conception) and first-trimester (90 days after conception). The relationship between SPE and season of conception was also examined. Hierarchical complementary log-log regression models were used to estimate the weather-SPE association.

RESULTS

SPE was diagnosed in 526 (0.8%) out of 63,633 singleton pregnancies. Increasing temperature or sunshine across both windows was associated with increased SPE risk. Early-pregnancy minimum temperature showed the strongest effect with adjusted odds ratio (OR) per 1 degree Celsius: 1.03 [95% confidence interval (CI) 1.01, 1.04]. The risk of SPE was higher when conception was in summer as compared to winter (OR 1.53, 95% CI 1.27, 1.85). Effect estimates showed only small variations in sensitivity analyses.

CONCLUSIONS

Our findings of a weather impact during early pregnancy on SPE may provide a new clue for understanding the causes of pre-eclampsia. Further investigation into the biologic mechanisms for this finding is required.

Blood pressure measured in the clinic and at home during pregnancy among nulliparous and multiparous women: the BOSHI study

BACKGROUND

Hypertension during pregnancy can cause serious problems during delivery, such as stroke, premature delivery, or low birthweight. Nulliparity is believed to be a risk factor for hypertension during pregnancy. However, the relationship between parity and blood pressure determined at home during pregnancy is still unknown.

METHODS

We assessed the incidence of gestational hypertension or preeclampsia in 575 nulliparous and multiparous women. Also, we examined blood pressure measured in the clinic and at home among 530 normotensive pregnant women who received antenatal care at a maternity hospital in Japan. Clinic blood pressures (CBPs) were obtained by duplicate measurement at each antenatal care visit. The participants were also required to measure their own blood pressures every morning at home while they were pregnant. A linear mixed model was used for analysis of the blood pressure course throughout pregnancy.

RESULTS

A total of 315 nulliparous and 215 multiparous women were entered into this study (mean age, 30.1 ± 4.6 years and 33.0 ± 4.1 years, respectively). CBP levels during pregnancy among nulliparous women were significantly higher than among multiparous women (P = 0.02/P <0.0001 for systolic/diastolic blood pressure), whereas there were no significant differences in home blood pressure (HBP) levels during pregnancy between the two groups (P = 0.4/P = 0.2 for systolic/diastolic blood pressure).

CONCLUSIONS

HBP levels during pregnancy were shown not to differ between nulliparous and multiparous women, while CBP levels during pregnancy were higher among nulliparous than among multiparous women.