The assessment of blood pressure in pregnant women: pitfalls and novel approaches

Accurate assessment of blood pressure is fundamental to the provision of safe obstetrical care. It is simple, cost effective, and life-saving. Treatments for preeclampsia, including antihypertensive drugs, magnesium sulfate, and delivery, are available in many settings. However, the instigation of appropriate treatment relies on prompt and accurate recognition of hypertension. There are a number of different techniques for blood pressure assessment, including the auscultatory method, automated oscillometric devices, home blood pressure monitoring, ambulatory monitoring, and invasive monitoring. The auscultatory method with a mercury sphygmomanometer and the use of Korotkoff sounds was previously recommended as the gold standard technique. Mercury sphygmomanometers have been withdrawn owing to safety concerns and replaced with aneroid devices, but these are particularly prone to calibration errors and regular calibration is imperative to ensure accuracy. Automated oscillometric devices are straightforward to use, but the physiological changes in healthy pregnancy and pathologic changes in preeclampsia may affect the accuracy of a device and monitors must be validated. Validation protocols classify pregnant women as a "special population," and protocols must include 15 women in each category of normotensive pregnancy, hypertensive pregnancy, and preeclampsia. In addition to a scarcity of devices validated for pregnancy and preeclampsia, other pitfalls that cause inaccuracy include the lack of training and poor technique. Blood pressure assessment can be affected by maternal position, inappropriate cuff size, conversation, caffeine, smoking, and irregular heart rate. For home blood pressure monitoring, appropriate instruction should be given on how to use the device. The classification of hypertension and hypertensive disorders of pregnancy has recently been revised. These are classified as preeclampsia, transient gestational hypertension, gestational hypertension, white-coat hypertension, masked hypertension, chronic hypertension, and chronic hypertension with superimposed preeclampsia. Blood pressure varies across gestation and by ethnicity, but gestation-specific thresholds have not been adopted. Hypertension is defined as a sustained systolic blood pressure of ≥140 mm Hg or a sustained diastolic blood pressure of ≥90 mm Hg. In some guidelines, the threshold of diagnosis depends on the setting in which blood pressure measurement is taken, with a threshold of 140/90 mm Hg in a healthcare setting, 135/85 mm Hg at home, or a 24-hour average blood pressure on ambulatory monitoring of >126/76 mm Hg. Some differences exist among organizations with respect to the criteria for the diagnosis of preeclampsia and the correct threshold for intervention and target blood pressure once treatment has been instigated. Home blood pressure monitoring is currently a focus for research. Novel technologies, including early warning devices (such as the CRADLE Vital Signs Alert device) and telemedicine, may provide strategies that prompt earlier recognition of abnormal blood pressure and therefore improve management. The purpose of this review is to provide an update on methods to assess blood pressure in pregnancy and appropriate technique to optimize accuracy. The importance of accurate blood pressure assessment is emphasized with a discussion of preeclampsia prediction and treatment of severe hypertension. Classification of hypertensive disorders and thresholds for treatment will be discussed, including novel developments in the field.

Correlation between central and uterine hemodynamics in hypertensive disorders of pregnancy

OBJECTIVE

Pregnancies affected by a hypertensive disorder (HDP) have increased uterine artery pulsatility index (UtA-PI) compared with that in healthy pregnancies. Women with HDP are also known to have lower cardiac output and increased systemic vascular resistance. The aim of this study was to investigate the relationship between central and uterine hemodynamics in HDP and uncomplicated pregnancy.

METHODS

This was a prospective study of HDP and normotensive control singleton pregnancies presenting at a tertiary referral hospital between January 2012 and December 2017. Paired measurements of maternal hemodynamics, using a non-invasive device (USCOM-1A®), and UtA-PI were performed in the third trimester. HDP pregnancies were divided into preterm (onset < 37 weeks' gestation) and term (onset ≥ 37 weeks). Spearman's rank coefficient was used to assess the correlation between the central and uteroplacental hemodynamics. Regression analysis was performed to assess the association of UtA-PI with independent variables.

RESULTS

We included 231 women with HDP (152 with preterm and 79 with term HDP) and 378 controls with normotensive pregnancy. Compared with controls, women with preterm HDP had significantly lower cardiac output (median (interquartile range (IQR)), 6.0 (5.1-7.2) vs 6.6 (5.8-7.5) L/min; P < 0.001) and significantly higher systemic vascular resistance (median (IQR), 1394 (1189-1670) vs 1063 (915-1222) dynes × s/cm⁵ ; P < 0.001) and UtA-PI (median (IQR), 1.0 (0.75-1.4) vs 0.67 (0.58-0.83); P < 0.001). Conversely, in women with term HDP, there were no significant differences in heart rate, cardiac output or UtA-PI compared with controls (all P > 0.05), while systemic vascular resistance was significantly higher (median (IQR), 1315 (1099-1527) vs 1063 (915-1222) dynes × s/cm⁵ ; P < 0.001). On multiple regression analysis, heart rate, mean arterial pressure and stroke volume were associated significantly with mean UtA-PI (all P < 0.001).

CONCLUSIONS

Differences observed between HDP and normotensive pregnancies in third-trimester UtA resistance are mirrored in the central maternal hemodynamic parameters. Late pregnancy differences in the uteroplacental circulation in preterm and term HDP are an index of maternal cardiovascular function rather than being related to inadequate spiral artery remodeling and impaired placentation. Copyright © 2018 ISUOG. Published by John Wiley & Sons Ltd.

Hypertensive Disorders of Pregnancy: Overview and Current Recommendations

Hypertensive disorders of pregnancy include chronic hypertension, gestational hypertension, preeclampsia-eclampsia, and chronic hypertension with superimposed preeclampsia. These disorders are an important cause of maternal and fetal morbidity and mortality. Although advances in effective treatments have been made, current research has yet to identify a biochemical or diagnostic imaging marker to reliably predict preeclampsia. Despite current guidelines that address diagnosis and management of hypertensive disorders in pregnancy, health care providers may overlook or be unaware of signs that require immediate evaluation and treatment. This article reviews the definitions of hypertensive disorders of pregnancy, diagnosis, pathophysiology of preeclampsia, indications for treatment, neurologic sequelae, and counseling about the implications of hypertension in pregnancy for subsequent health.

[Treatment of arterial hypertension in pregnancy in relation to current guidelines of the Polish Society of Arterial Hypertension from 2011]

Arterial hypertension concerns 7-10% of pregnancies and leads to an increased risk of complications for both, the mother and the child. This rate will probably rise in the years to come due to the notable tendency among women to delay the decision to become pregnant - values of blood pressure and occurrence of arterial hypertension increase with age, as well as due to the growing problem of obesity resulting from inappropriate dietary habits and lack of regular everyday physical activity. Difficulties with management of that clinical condition are partly related with lack of unified and widely accepted guidelines. Different opinions in the subject of terminology and classification of pregnancy hypertension or indications for pharmacotherapy as well as choice of the optimal antihypertensive drug, emerge from objective causes such as combination of various pathogenetic factors typical for arterial hypertension itself and those connected with pregnancy elsewhere stressed priorities of therapy from the point of view of the health of the mother and of the fetus, as well as lack of randomized clinical trials due to obvious ethical purposes, but also from the fact that pregnancy hypertension is a focus of attention for different specialists - obstetricians, hypertensiologists and perinatologists. A good cooperation regarding experience and information among all of these specializations would be the most beneficial for pregnant women and their children. Lack of new modern antihypertensive agents, safe and effective in pregnancy while the older ones are being withdrawn from the market as their production is no longer cost-effective for pharmacological companies, has become an increasing problem in many countries, and Poland among them. The aim of the following publication was to present the statement on management of pregnancy hypertension from the current guidelines of the Polish Society of Arterial Hypertension 2011 to gynecologists and obstetricians, with a commentary According to the guidelines, methyldopa, labetalol (or metoprolol), long-acting nifedipine or verapamil should be used in the therapy of mild and moderate pregnancy hypertension, preferably in the given order In case of severe and life-threatening arterial hypertension, labetalol intravenously should be administered and if it is still not sufficient, eventually sodium nitroprusside or hydralazine could be ordered, bearing in mind their possible adverse effects. Unfortunately labetalol, nifedipine, hydralazine and sodium nitroprusside are no longer available in Poland, which significantly narrows the practical treatment possibilities in the pregnant population. Inhibitors of angiotensin converting enzyme and angiotensin II receptor blockers are contraindicated during pregnancy and breastfeeding, as well as aldosteron inhibitors, as suggest in the guidelines. In the paper the authors present the guidelines and also, based on the information available to date in medical journals, other hypertension pharmacotherapeutic options possible for consideration in pregnancy which could be helpful in management of severe arterial hypertension in pregnancy.

Pregnancy-induced hypertension--a particular pathogenic model. Similarities with other forms of arterial hypertension

Hypertension is in 85 to 90% of cases of unknown etiology, in spite of efforts undertaken by modern medicine to elucidate it. Numerous experimental studies were conducted in order to explain the pathogeny of this disease. Recent observations revealed that during therapy with anti-VEGF medication,used in treating different forms of cancer, hypertension and proteinuria occur, and at kidney level endothelial injuries appear similar to pregnancy-related hypertension. Antiangiogenic factors, such as sFlt-1, are produced during pregnancy-induced hypertension, especially in preeclampsia. They block the circulating VEGF. Consequently, proteinuria, and sometimes oedema occur together with hypertension. Renal injuries are of glomerular endotheliosis type. It is appreciated that one can draw a parallel between these pathologic situations, as is ablative treatment of antiangiogenic medication (anti-VEGF) and pregnancy-induced hypertension, preeclampsia, respectively. Since in pregnancy-induced hypertension angiogenic factors have an important role, we analyse their implication in other types of hypertension, in myocardial infarction, and in endothelial dysfunction in the course of CKD. The main pathogenic mechanism of pregnancy-induced hypertension that causes the disease is placental ischaemia. This is followed by the placental release of pressor substances that are involved both in generalised endotheliosis that characterizes the disease, and in hypertension. The prototype hypertension caused by renal ischaemia is renal artery stenosis. Both pregnancy-induced hypertension and hypertension in renal artery stenosis have a similar factor in their pathogeny, that is organ ischaemia with production of consecutive pressor substances. Since this ischaemic factor can intervene in other forms of hypertension, its characterisation becomes of importance at present. Thus, pregnancy-induced hypertension in pregnancy can represent a real pathogenic model of hypertension that is reflected in non-pregnancy hypertension. The paper presents the particularities of pregnancy-induced hypertension, as well as its parallelism with other types of hypertension that are determined by organ ischaemia or that produce ablation of angiogenic factors.

Comparison between essential hypertension and pregnancy-induced hypertension: a genetic perspective

Essential hypertension (EH) accounts for 80-90% of hypertension, and pregnancy-induced hypertension (PIH) is responsible for hypertension during pregnancy. Both considered multifactorial disorders. While both have many features in common, conditions and causes of these diseases have yet to be clarified. Since both diseases are associated with hypertension, the genetic backgrounds may contain common features. The present study reviewed similarities and differences between women with EH and PIH, with a particular focus on their genetic backgrounds.

Stress, symptoms, self-monitoring confidence, well-being, and social support in the progression of preeclampsia/gestational hypertension

OBJECTIVE

To investigate the relationships of psychological stress, preeclampsia/gestational hypertension symptoms, confidence in self-monitoring, well-being, and perceived social support with preeclampsia/gestational hypertension disease progression in outpatient women. Women with mild and severe preeclampsia/gestational hypertension were compared for differences in these variables.

DESIGN

A retrospective, correlational, and comparative design.

SETTING

Postpartum units of three urban hospitals in Philadelphia, Pennsylvania.

PARTICIPANTS

One hundred postpartum women with preeclampsia/gestational hypertension.

MAIN OUTCOME MEASURES

Psychological stress measured by the Perceived Stress Scale, preeclampsia/gestational hypertension symptoms by the Preeclampsia/Gestational Hypertension Checklist, confidence in self-monitoring by the Self-Confidence in Self-Monitoring Scale, well-being by the Index of Well-Being, and social support by the Interpersonal Support Evaluation List.

RESULTS

Women with worsening/severe preeclampsia/gestational hypertension reported a significantly higher number of symptoms than women with mild preeclampsia/gestational hypertension (p= .02). Psychological stress was significantly higher (p= .04) in women with worsening/severe preeclampsia/gestational hypertension. There were no differences in well-being, self-confidence in self-monitoring, or perceived social support between women with mild preeclampsia/gestational hypertension and those with worsening preeclampsia/gestational hypertension.

CONCLUSION

Worsening/severe preeclampsia/gestational hypertension was associated with increasing psychological stress and a higher number of preeclampsia/gestational hypertension symptoms.

Invited commentary: identifying women with hypertension during pregnancy--is high specificity sufficient?

Hypertensive complications of pregnancy contribute to the burden of maternal morbidity and subsequently have an impact on neonatal morbidity and mortality. Although codes from the International Classification of Diseases should delineate the specific subtypes of pregnancy-related hypertension, how diagnoses are applied and how these codes are used in clinical settings are largely unknown. This commentary discusses the implications of using administrative codes to identify women with preeclampsia syndromes, especially when used to define outcomes or exposures for etiologic research.

Hypertensive Pregnancy Disorders: Current Concepts

Hypertensive pregnancy disorders complicate 10% of all pregnancies and cover a spectrum of conditions, namely preeclampsia, eclampsia, and chronic and gestational hypertension. Preeclampsia is a pregnancy-specific disorder clinically characterized by hypertension and proteinuria that occurs after 20 weeks of gestation. It remains a leading cause of both fetal and maternal morbidity and mortality worldwide. Traditionally, hypertensive pregnancy disorders were considered not to have any long-term impact on mothers' cardiovascular health; however, recent studies consistently have supported the role of hypertension in pregnancy as a risk factor for cardiovascular disease later in life. Therefore, improved screening, and preventive and treatment strategies may not only optimize management of hypertensive pregnancy disorders, but may have a long-term impact on women's cardiovascular events and outcomes years after the affected pregnancies. This article will provide a brief review of hypertensive pregnancy disorders and important recent discoveries regarding their pathogeneses, while focusing on current diagnostic and treatment strategies.

Methods for dealing with discrepant records in linked population health datasets: a cross-sectional study

BACKGROUND

Linked population health data are increasingly used in epidemiological studies. If data items are reported on more than one dataset, data linkage can reduce the under-ascertainment associated with many population health datasets. However, this raises the possibility of discrepant case reports from different datasets.

METHODS

We examined the effect of four methods of classifying discrepant reports from different population health datasets on the estimated prevalence of hypertensive disorders of pregnancy and on the adjusted odds ratios (aOR) for known risk factors. Data were obtained from linked, validated, birth and hospital data for women who gave birth in a New South Wales hospital (Australia) 2000-2002.

RESULTS

Among 250,173 women with linked data, 238,412 (95.3%) women had perfect agreement on the occurrence of hypertension, 1577 (0.6%) had imperfect agreement; 9369 (3.7%) had hypertension reported in only one dataset (under-reporting) and 815 (0.3%) had conflicting types of hypertension. Using only perfect agreement between birth and discharge data resulted in the lowest prevalence rates (0.3% chronic, 5.1% pregnancy hypertension), while including all reports resulted in the highest prevalence rates (1.1 % chronic, 8.7% pregnancy hypertension). The higher prevalence rates were generally consistent with international reports. In contrast, perfect agreement gave the highest aOR (95% confidence interval) for known risk factors: risk of chronic hypertension for maternal age > or =40 years was 4.0 (2.9, 5.3) and the risk of pregnancy hypertension for multiple birth was 2.8 (2.5, 3.2).

CONCLUSION

The method chosen for classifying discrepant case reports should vary depending on the study question; all reports should be used as part of calculating the range of prevalence estimates, but perfect matches may be best suited to risk factor analyses. These findings are likely to be applicable to the linkage of any specialised health services datasets to population data that include information on diagnoses or procedures.

Selective magnesium sulfate prophylaxis for the prevention of eclampsia in women with gestational hypertension

OBJECTIVE

To describe the incidence of eclampsia in women with mild gestational hypertension when only women with severe gestational hypertension are given magnesium sulfate prophylaxis.

METHODS

This is a prospective 4(1/2)-year observational study. Those women who met our criteria for severe gestational hypertension received intravenous magnesium sulfate prophylaxis, and women with nonsevere hypertension did not. Data were collected at delivery to ascertain the incidence of eclampsia and maternal and neonatal morbidity.

RESULTS

A total of 72,004 women were delivered during the study period, 6,431 had gestational hypertension, 3,935 met the criteria for severe disease and were given magnesium sulfate prophylaxis, 2,496 women with nonsevere hypertension were not treated. Eighty-seven women developed eclampsia, for an overall incidence of 1 in 828 deliveries, a 50% increase when compared with 5 preceding years where all women with gestational hypertension were given magnesium sulfate prophylaxis. Of the 2,496 women with nonsevere hypertension who were not treated, 27 had eclampsia (1 in 92). Women with eclampsia were more likely to require general anesthesia for cesarean delivery compared with hypertensive women without eclampsia (23% versus 4%, P < .001), but they had no additional morbidity. Infants of eclamptic mothers had more adverse outcomes than those without convulsions (12% versus 1%, P < .04).

CONCLUSION

Selective magnesium sulfate prophylaxis results in an increased overall incidence of eclampsia because of more seizures in women with nonsevere gestational hypertension who are not given magnesium sulfate prophylaxis.

LEVEL OF EVIDENCE

II-3.

Proteinuria in hypertensive pregnancy diseases is associated with a longer persistence of hypertension postpartum

As there is growing evidence that hypertensive pregnancy disorders are associated with a risk of cardiovascular diseases later, the resolution of hypertension postpartum (PP) is of high clinical significance. However, there is little knowledge about the factors that influence this normalization. The objectives of our study were (a) to investigate whether or not there are differences in the resolution of hypertension between the distinct types of hypertensive pregnancy disorders and (b) to analyse what clinical parameters may determine the resolution pattern PP. In this retrospective study, 52 patients with preeclampsia (PE), seven with HELLP syndrome (haemolysis, elevated liver enzymes, low platelets), 10 with chronic hypertension (CH) and 21 with pregnancy-induced hypertension (PIH) were recruited. The course of the clinical parameters until day 7 PP was documented. Patients with proteinuria (PE/HELLP) showed the highest blood pressure values PP, while patients with PIH and CH showed no blood pressure changes up to day 7 PP. In patients with proteinuric diseases, there was a significantly higher percentage of cases with persisting hypertension at day 3 PP (71% vs 48% PIH/CH group, P<0.05), and even at day 7 PP this percentage remained significantly higher (31% vs 19% PIH/CH group). Our study shows that patients with proteinuric pregnancy disorders have a delayed PP of hypertension. A high percentage of these women are discharged from hospital with persisting hypertension and proteinuria. These observations demand a more specific and long-term PP care for these women.

[Differences and similarities of preeclampsia and gestational hypertension]

Current criteria regarding hypertension in pregnancy consider two distinct types: gestational hypertension (pure type) and preeclampsia-eclampsia syndrome, the latter with albuminuria as a mandatory clinical fact. However, reports of lasts years show that a 15 to 46% of cases classified as pure type gestational hypertension evolve to a preeclamptic state, underlying the possibility that both clinical conditions represent diferent stages of the same disease. On the other hand, albuminuria may not be present in severe cases of pregnancy-related hypertensive disorders such as HELLP syndrome or eclampsia. It follows that if albuminuria is not necessary to establish the most severe forms of the disease, must the non-albuminuric hypertensive-type still be considered as a diferent diagnosis? This report reviews the medical literature on the subject, stressing similarities and diferences of both conditions in order to reflect about the need to change the classification concepts pregnancy-related hypertensive entities.