Methods of assessment of the arterial pulse wave in normal human pregnancy

Alterations in Vessel Hemodynamics Across Uncomplicated Pregnancy

Pregnancy is marked by the onset of rapid hemodynamic alterations in order to accommodate the needs of the developing fetus. Arterial stiffness is an independent predictor of cardiovascular events and mortality, and its measurement in clinical practice has been recommended. It follows a U-shaped curve in uncomplicated pregnancy, decreasing to a nadir in mid-pregnancy and rising at term. Systemic vasodilation occurs due to elevated nitric oxide, prostacyclin, endothelium-derived hyperpolarizing factor, estrogen, progesterone, and relaxin. Vascular resistance decreases to a nadir in mid-pregnancy, while endothelial function is enhanced starting in the first trimester. Plasma volume increases by about 50%, and total red blood cell mass increases by up to 40%. Cardiac output increases by up to 45%, at first due primarily to elevated stroke volume, then mainly due to increased heart rate. Along with echocardiography, cardiac magnetic resonance imaging is safe for use in pregnancy. It may assess cardiac function more accurately than echocardiography, and may be indicated in specific clinical cases. Moreover, blood pressure decreases to a nadir in mid-pregnancy and rises to near preconception values postpartum. An appreciation of the vascular changes occurring in healthy pregnancy can aid in the prediction and diagnosis of pregnancy complications, such as preeclampsia and other hypertensive disorders of pregnancy, and inform treatment. In particular, noninvasive arterial stiffness/hemodynamics assessment provides unique clinical information beyond blood pressure and traditional maternal characteristics, and can signal a need for further testing, or be used in combination with other tests to predict or diagnose complications of pregnancy.

Hemodynamic changes in pregnancy: does central blood pressure have any role?

Pregnancy is associated with alteration in the hemodynamic state. In clinical practice, only peripheral blood pressure is measured; however, central blood pressure is a better predictor of cardiovascular events. We have investigated variations in peripheral blood pressure, central blood pressure, and augmentation index in healthy non-pregnant and pregnant women. This was a cross-sectional study of 107 pregnant women (I trimester n = 19, II trimester n = 39, and III trimester n = 49) and age-matched 53 non-pregnant women (Follicular phase n = 25 and luteal phase n = 28). The augmentation index showed a significant decrease with the progression of pregnancy. Central systolic blood pressure showed a decreasing trend (non-significant) with the progression of pregnancy. Heart rate shows a significant increase from follicular to luteal phase in non-pregnant women, which further increases with the progression of pregnancy. Longitudinal studies involving larger sample sizes might provide some insights into the significance of including central blood pressure and augmentation index for routine checkups in both non-pregnant and pregnant women.

Changes in Vascular Function from Preconception to Postpartum Among Mongolian Women

Background: Pregnancy is associated with physiological changes to meet the metabolic demands of the growing fetus. To understand adverse pregnancy outcomes it is important to establish vascular changes throughout pregnancy. We examined longitudinal changes in vascular measurements from prepregnancy through postpartum. Materials and Methods: Seventy women planning to conceive in Ulaanbaatar, Mongolia enrolled in this prospective study. Within 6 months, 44 (63%) had conceived; of which 36 (82%) delivered. Ten (28%) developed complex pregnancies and were analyzed separately. Vascular measures included central systolic blood pressure (cSBP), central diastolic blood pressure (cDBP), augmentation index corrected for heart rate of 75 beats/minute (AIx-75), and pulse wave velocity (PWV). Measurements were performed at prepregnancy, second trimester (22-24 weeks), third trimester (34-36 weeks), and 2 months postpartum. Missing values (n = 0-6 per time period) were replaced by multiple imputation. A repeated measures analysis of variance analyzed changes within individual women over the four time points adjusted for age, parity, and body mass index. Results: We observed significant reductions from prepregnancy to second trimester for mean Alx-75 (17.1%-12.6%; p = 0.006) and cSBP (91.7-86.8 mmHg; p = 0.03) but not for cDBP or PWV. Both mean AIx-75 and cSBP increased in third trimester. In the postpartum, cSBP returned to prepregnancy levels, whereas AIx-75 exceeded prepregnancy levels, although this fell short of significance (p = 0.09). Similar vascular patterns were observed in women with complex pregnancies for AIx-75; however, PWV increased from the second trimester and remained higher through postpartum, although not significant. Conclusion: In Mongolian women, we observed a decrease in AIx-75 and cSBP from prepregnancy through second trimester, which resolved postpartum. These results provide an understanding of changes across pregnancies in an Asian country. Future studies should assess vascular changes across pregnancies to determine if it can predict conditions such as pre-eclampsia.

The Nine Month Stress Test: Pregnancy and Exercise - Similarities and Interactions

Of all physiological systems, the cardiovascular system takes on the most profound adaptation in pregnancy to support fetal growth and development. The adaptations that arise are systemic and involve structural and functional changes that can be observed at the cerebral, central, peripheral, and microvascular beds. This includes, although is not limited to increased heart rate, stroke volume and cardiac output with negligible change to blood pressure, reductions in vascular resistance and cerebral blood flow velocity, systemic artery enlargement, enhanced endothelial function. All of this takes place to accommodate blood volume expansion and ensure adequate fetal and maternal oxygen delivery. In some instances, the demand placed on the vasculature can manifest as cardiovascular maladaptation and thus, cardiovascular complications can arise. Exercise is recommended in pregnancy because of its powerful ability to reduce the incidence and severity of cardiovascular complications in pregnancy. However, the mechanism by which it acts is poorly understood. The first aim of this review is to describe the systemic adaptations that take place in pregnancy. Secondly, this review aims to describe the influence of exercise on these systemic adaptations. It is anticipated that this review can comprehensively capture the extent of knowledge in this area while identifying areas that warrant further investigation.

Effect of supraphysiological estrogen levels on arterial stiffness and hemodynamic parameters

OBJECTIVE

The present study evaluates the arterial stiffness and hemodynamic parameters in patients with a supraphysiological estrogen level due to in vitro fertilization (IVF) with controlled ovarian hyperstimulation (COH).

METHODS

A total of 82 female patients aged 24-45 years were included. Their arterial stiffness parameters were analyzed before and after the appropriate COH protocol involving arteriography using Mobil-O-Graph NG (IEM GmbH, Stolberg, Germany) 24-hour ambulatory blood pressure monitor.

RESULTS

Systolic, diastolic, mean, central systolic, and diastolic blood pressures, as well as peripheral vascular resistance, were significantly lower after COH therapy (p=0.001, 0.002, <0.001, <0.001, 0.040, and <0.001, respectively). In contrast, there was no statistically significant difference observed in heart rate, pulse pressure, or cardiac output. The pulse wave velocity measurement was significantly lower after COH than the baseline levels [5.3 m/s (4.5-6.9 m/s) versus 5.4 m/s (4.7-7.3 m/s,); p<0.001], but the augmentation index was not significantly different [28% (4%-41%) versus 29% (5%-43%); p=0.090]. When the patients were grouped according to the occurrence of a pregnancy after IVF therapy, all parameters were not different between the pregnancy (+) and pregnancy (-) patients (p>0.05).

CONCLUSION

Arterial stiffness and hemodynamic parameters significantly decreased in IVF patients who underwent COH therapy. The long-term clinical significance of this short-term effect should be investigated with prospective studies. There was no significant difference in all parameters before and after COH when the pregnancy (+) and pregnancy (-) patients were compared.

Central haemodynamics in normal pregnancy: a prospective longitudinal study

OBJECTIVE

To conduct a longitudinal evaluation of the central haemodynamic adaptations of normal pregnancy.

METHODS

This was a prospective longitudinal study involving healthy, normotensive women who were having an uncomplicated, singleton pregnancy. Brachial and central SBP, DBP, mean arterial pressure (MAP), brachial and central pulse pressure (PP), aorta-to-brachial pulse pressure amplification (AMPA-B), heart rate (HR), augmentation index adjusted for HR (AIx75), carotid-femoral pulse wave velocity (cfPWV) and cardiac output (CO) were measured at a mean gestational age of 14, 24 and 36 weeks.

RESULTS

One hundred women were followed prospectively throughout pregnancy. Brachial and central SBP, DBP and MAP decreased slightly in early gestation, followed by a significant increase in late gestation (P < 0.05). Brachial PP was lowest in the final trimester (P = 0.011) whereas central PP remained unchanged, resulting in a significant decrease in AMPA-B (P < 0.001). HR and AIx75 rose continuously throughout pregnancy (P < 0.001). A significant fall in cfPWV was observed mid-pregnancy, which remained significant after adjustment for MAP and HR (P < 0.05). CO rose mid-pregnancy, before returning to baseline values by week 36 of gestation (P < 0.05).

CONCLUSION

To our knowledge, this is the largest prospective study to evaluate several central haemodynamic parameters in normotensive pregnancies, including adjusted-AIx and the gold-standard cfPWV. These data are a necessary foundation for the establishment of pregnancy-specific reference values and provide reference data for future trial design.

Changes of Arterial Pulse Waveform Characteristics with Gestational Age during Normal Pregnancy

Arterial pulse waveform analysis has been widely used to reflect physiological changes in the cardiovascular system. This study aimed to comprehensively investigate the changes of waveform characteristics of both photoplethysmographic (PPG) and radial pulses with gestational age during normal pregnancy. PPG and radial pulses were simultaneously recorded from 130 healthy pregnant women at seven gestational time points. After normalizing the arterial pulse waveforms, the abscissa of notch point, the total pulse area and the reflection index were extracted and compared between different measurement points and between the PPG and radial pulses using post-hoc multiple comparisons with Bonferrioni correction. The results showed that the effect of gestational age on all the three waveform characteristics was significant (all p < 0.001) after adjusting for maternal age, heart rate and blood pressures. All the three waveform characteristics demonstrated similar changing trends with gestational age, and they were all significantly different between the measurements from gestational week 12–15 and the others (all p < 0.05, except for the PPG total pulse area between the first and second measurement points). In conclusion, this study has comprehensively quantified similar changes of both PPG and radial pulse waveform characteristics with gestational age.

The influence of prenatal exercise and pre-eclampsia on maternal vascular function

During healthy pregnancy, the cardiovascular system undergoes diverse adaptations to support adequate transfer of oxygen and nutrients from mother to fetus. In order to accommodate the large expansion of blood volume and associated cardiac output, the structure, mechanics, and function of the arteries are altered. Specifically, in healthy pregnancy there is a remodeling of arteries (increased angiogenesis and vasodilation), a generalized reduction in arterial stiffness (increased compliance), and an enhanced endothelial function. The development of pregnancy complications, specifically pre-eclampsia, is associated with poor placentation (decreased angiogenesis), increased arterial stiffness, and vascular dysfunction (reduced endothelial function). Many of the positive adaptations that occur in healthy pregnancy are enhanced in response to chronic exercise. Specifically, placental angiogenesis and endothelial function have been shown to improve to a greater extent in women who are active during their pregnancy compared with those who are not. Prenatal exercise may be important in helping to reduce the risk of vascular dysfunction in pregnancy. However, our knowledge of the vascular adaptations resulting from maternal exercise is limited. This review highlights maternal vascular adaptations occurring during healthy pregnancy, and contrasts the vascular maladaptation associated with pre-eclampsia. Finally, we discuss the role of prenatal exercise on vascular function in the potential prevention of vascular complications associated with pre-eclampsia.

Association between uterine artery Doppler blood flow changes and arterial wall elasticity in pregnant women

INTRODUCTION

Uterine artery (UtA) Doppler velocimetry changes and increased arterial stiffness are associated with preeclampsia. We aimed to investigate the relation between UtA velocimetry changes and arterial stiffness in pregnant women.

METHODS

Doppler velocimetry and photoplethysmographic digital pulse wave analysis (DPA) were performed in 173 pregnant women in the second or the third trimester, where UtA Doppler pulsatility index (PI), diastolic notching, and UtA score (UAS) combining notching and high PI were calculated. DPA stiffness parameters representing large arteries were ejection elasticity index (EEI) and b/a, small arteries dicrotic index (DI) and d/a, and global stiffness the aging index (AI).

RESULTS

One hundred and thirty women had normal Doppler and 43 had diastolic notching, of whom nine had high PI. DI indicated increased stiffness in small arteries when notching was present (p = 0.044) and showed a significant but weak correlation to UAS (p = 0.025, tau 0.12). EEI and b/a indicated increased large artery stiffness (p ≤0.014), d/a small artery stiffness (p = 0.023), and AI a systemic stiffness (p = 0.040) when high PI.

CONCLUSION

High UtA PI was associated with increased systemic arterial stiffness, whereas notching was related to increased stiffness in small arteries only. This indicates pathophysiological differences between the two Doppler parameters.

Sphygmology of ibn sina, a message for future

Sphygmology is a 2000-year-old method that is still used in some traditional medicine systems, mainly Iranian, Chinese and Ayurveda. Ibn Sina is one of the most popular physicians in the history of Sphygmology, who had made great contributions to this method, but few meticulous studies have been made on his concepts. In this article, his standpoints on Pulsology are studied. Ibn Sina has mentioned 10 parameters for pulse palpation, and 13 compound pulses, as well. Besides, some pulse patterns applicable for differentiating similar diseases have been introduced. Nowadays some concepts on pulse patterns, such as pulse change in sleep and pregnancy have been studied; but unfortunately many of the ideas on Pulsology have not yet been examined. Sphygmology, as an accessible and inexpensive means, having a substantial diagnosis yield, has been accepted by the people since its rise, and its development over centuries ago. Although some new instruments have been innovated, which can measure different parameters of pulse, yet sphygmology can be one of the most commonly usable diagnostic methods in future, not only applicable by cardiologists but also by all the physicians.

Improving maternal and perinatal outcomes in the hypertensive disorders of pregnancy: a vision of a community-focused approach

The hypertensive disorders of pregnancy (HDP; pre-existing hypertension, gestational hypertension, and pre-eclampsia) remain important causes of maternal morbidity and mortality, especially in low- and middle-income countries. The paper summarizes the current state of evidence around possible technologies to support community-based improvements in maternal and perinatal outcomes for women with pre-eclampsia. Through the testing and, where proven, introduction of these technologies, we believe that HDP-related progress toward achieving Millennium Development Goal 5 can best be accelerated. The evidence and discussion are presented under the following headings: (1) prediction; (2) prevention; (3) diagnosis; (4) risk stratification; (5) decision aids; (6) treatment; (7) geographic information systems; (8) communication; and (9) community and patient education.

The pulse spectrum analysis at three stages of pregnancy

OBJECTIVES

This study is the first to detect the radial pulses of the three diagnosis positions (inch, bar, and cubit) in both wrists (six positions) by pulse spectrum analysis. The purpose of this study was to identify the difference among pulses of the six positions at three stages of pregnancy and to examine whether the results of this study agree with the theory of Traditional Chinese Medicine (TCM), which states that the cubit pulse shows unique changes for an expectant woman and that the pulse changes coincide with the progression of gestation.

SUBJECTS AND METHODS

One hundred and fifty (150) healthy pregnant women were divided into three groups according to gestational age (9-14 weeks, 20-28 weeks, and 32-37 weeks of gestation) and 50 healthy nonpregnant women were used as controls. A pulse analyzer was used to detect the six positions of the radial pulses and to calculate the 10 relative energy values of the spectrum's harmonics of the six positions.

RESULTS

Results show that most of the 10 relative spectral energy values of the right and left cubits are statistically (p<0.01) higher than those of the inch for the pregnant women as compared with the nonpregnant women. In addition, the 10 relative spectral energy values of the six positions are not identical at the three stages of pregnancy.

CONCLUSIONS

The cubit pulse is unique for pregnant women, which is consistent with the theory of TCM. In addition, the pulse conditions at the three stages of pregnancy are dissimilar.

The long-term effects of prematurity and intrauterine growth restriction on cardiovascular, renal, and metabolic function

Objective. To determine relative influences of intrauterine growth restriction (IUGR) and preterm birth on risks of cardiovascular, renal, or metabolic dysfunction in adolescent children. Study Design. Retrospective cohort study. 71 periadolescent children were classified into four groups: premature small for gestational age (SGA), premature appropriate for gestational age (AGA), term SGA, and term AGA. Outcome Measures. Systolic blood pressure (SBP), augmentation index (Al), glomerular filtration rate (GFR) following protein load; plasma glucose and serum insulin levels. Results. SGA had higher SBP (average 4.6 mmHg) and lower GFR following protein load (average 28.5 mL/min/1.73 m²) than AGA. There was no effect of prematurity on SBP (P = .4) or GFR (P = .9). Both prematurity and SGA were associated with higher AI (average 9.7%) and higher serum insulin levels 2 hr after glucose load (average 15.5 mIU/L) than all other groups. Conclusion. IUGR is a more significant risk factor than preterm birth for later systolic hypertension and renal dysfunction. Among children born preterm, those who are also SGA are at increased risk of arterial stiffness and metabolic dysfunction.

Maternal arterial stiffness in pregnancies affected by Type 1 diabetes mellitus

AIM

There is little information about maternal central haemodynamics and arterial stiffness in pregnancies affected by Type 1 diabetes mellitus. The aim of the current study was to investigate whether maternal arterial stiffness is altered in pregnant women with Type 1 diabetes mellitus compared with women with uncomplicated pregnancies.

METHODS

This was a cross-sectional study involving 37 pregnant women without diabetes and 37 pregnant women with Type 1 diabetes mellitus during the second trimester of pregnancy. Maternal wave reflection (augmentation index) and pulse wave velocity of the carotid-femoral and carotid-radial part of the arterial tree were assessed non-invasively using applanation tonometry.

RESULTS

Pregnant women with normal pregnancies and Type 1 diabetes mellitus had similar augmentation index (3.7 +/- 12.8 vs. 5.1 +/- 12.6%, P = 0.6), even after adjusting for possible confounders. Within the group of diabetic women, augmentation index was associated with duration of diabetes (P = 0.003, r(2) = 0.22) but not with glycated haemoglobin. Pulse wave velocities were similar between the two groups of women (carotid-femoral: 5.6 +/- 0.9 vs. 5.7 +/- 1.1 m/s, P = 0.4; carotid-radial: 7.4 +/- 1.2 vs. 7.8 +/- 1 m/s, P = 0.1). In the diabetic women there was no significant association between the pulse wave velocities and either duration of diabetes or glycated haemoglobin.

CONCLUSIONS

Pregnancy in women with Type 1 diabetes mellitus is not associated with altered maternal systemic arterial stiffness. However, maternal wave reflections increase with the duration of diabetes.

Maternal arterial stiffness in pregnancies affected by preeclampsia

Preeclampsia (PE) is characterized by an aberrant maternal cardiovascular adaptation to pregnancy and increased cardiovascular risk later on in life. The aim of this study was to compare the maternal wave reflections and arterial stiffness in women with established PE and those with normotensive pregnancies, after systematic adjustment for known confounders. This was a cross-sectional study involving 69 normotensive, pregnant women and 54 women with established PE. Maternal wave reflection (augmentation index) and pulse wave velocity of the carotid-radial and carotid-femoral parts of the arterial tree were assessed noninvasively using applanation tonometry. The measurements were adjusted for maternal age, heart rate, mean arterial pressure, and aortic time to wave reflection and expressed as multiples of the median (MoM) of the control group. In the PE group, compared with controls, there was an increase in the median pulse wave velocity of both the carotid to femoral [1.1, interquartile rage (IQR) 1.0–1.3 MoM vs. 0.9, IQR 0.9–1.0 MoM; P < 0.0001] and carotid to radial (1.0, IQR 0.9–1.1 MoM vs. 0.9, IQR 0.9–1.0 MoM; P = 0.01) parts of the arterial tree. In contrast, there were no significant differences between the two groups in the median augmentation index (0.9, IQR 0.7–1.1 MoM vs. 1.0, IQR 0.5–1.8 MoM; P = 0.46). In conclusion, we found that established PE is characterized by increased maternal arterial stiffness but not altered maternal wave reflection.

Pulse wave analysis in normal pregnancy: a prospective longitudinal study

Background

Outside pregnancy, arterial pulse wave analysis provides valuable information in hypertension and vascular disease. Studies in pregnancy using this technique show that vascular stiffness is raised in women with established pre-eclampsia. We aimed to establish normal ranges for parameters of pulse wave analysis in normal pregnancy and to compare different ethnic groups.

Methodology/Principal Findings

This prospective study was conducted at The Homerton University Hospital, London between January 2006 and March 2007. Using applanation tonometry, the radial artery pulse waveform was recorded and the aortic waveform derived. Augmentation pressure (AP) and Augmentation Index at heart rate 75/min (AIx-75), measures of arterial stiffness, were calculated.

We recruited 665 women with singleton pregnancies. Women who developed pre-eclampsia (n = 24, 3.6%) or gestational hypertension (n = 36, 5.4%) were excluded. We also excluded 47 women with other pregnancy complications or incomplete follow-up, leaving 541 healthy normotensive pregnant women for subsequent analysis. In the overall group of 541 women, there were no significant changes in AP or AIx-75 as pregnancy progressed. In 45 women followed longitudinally, AP and AIx-75 fell significantly from the first to the second trimester, then rose again in the third (P<0.001). The two main ethnic groups represented were Caucasian (n = 229) and Afrocaribbean (n = 216). There were no significant differences in AP or AIx-75 in any trimester between these two ethnic groups.

Conclusions

This study is the largest to date of pulse wave analysis in normal pregnancy, the first to report on a subset of women studied longitudinally, and the first to investigate the effect of ethnicity. These data provide the foundation for further investigation into the potential role of this technique in vascular disorders in pregnancy.

Influence of the Menstrual Cycle, Pregnancy, and Preeclampsia on Arterial Stiffness

Arterial stiffness and compliance are major predictors of adverse cardiovascular events and are influenced by female sex hormones, including estrogen and progesterone. The aim of this longitudinal study was to evaluate the effect of the menstrual cycle, normal pregnancy, and preeclampsia on central and systemic arterial stiffness. Ten healthy nulliparous women with regular menses were studied in the early and midfollicular, periovulatory, and luteal phases of a single menstrual cycle. Twenty-two primigravida pregnant women were studied throughout pregnancy at 16, 24, 32, and 37 weeks gestation and at 7 weeks postpartum. Fifteen primigravida women with preeclampsia were studied at diagnosis and 7 weeks postpartum. Augmentation index and carotid-radial and carotid-femoral pulse wave velocities were measured using applanation tonometry. Augmentation index fell during the luteal phase of the menstrual cycle (luteal phase versus periovulatory phase; P <0.05). In normal pregnancy, pulse wave velocity and augmentation index increased from 24 weeks over the third trimester ( P ≤0.01 for both). All of the measures were increased in women with preeclampsia ( P ≤0.01), with augmentation index and carotid-femoral pulse wave velocity remaining elevated 7 weeks postpartum ( P ≤0.02). We conclude that systemic arterial stiffness undergoes major changes during the menstrual cycle and pregnancy and that preeclampsia is associated with greater and more prolonged increases in arterial stiffness. These effects may contribute to adverse cardiovascular outcomes of pregnancy and preeclampsia.

Antihypertensive therapy and central hemodynamics in women with hypertensive disorders in pregnancy

OBJECTIVE

To estimate the changes in central hemodynamics features of pregnant women presenting with hypertensive disorders and to analyze the effects of standard antihypertensive treatment on maternal central hemodynamics.

METHODS

Applanation tonometry was used to record the radial artery pulse waveform in 80 women presenting with preeclampsia or gestational hypertension and 80 normotensive controls matched for gestational age. In each case, an averaged aortic waveform was derived and analyzed to calculate augmentation pressure and augmentation index at heart rate 75 beats per minute (bpm).

RESULTS

In women with preeclampsia and gestational hypertension, both augmentation pressure (P<.001 and P<.05, respectively) and augmentation index at heart rate 75 bpm (P<.001 and P<.001, respectively) were significantly higher than in controls. Augmentation pressure and augmentation index at heart rate 75 bpm were significantly higher in early- compared with late-onset preeclampsia (P<.001) and in severe compared with mild preeclampsia (P<.001). Antihypertensive therapy with alpha methyldopa resulted in a significant fall in both augmentation pressure and augmentation index at heart rate 75 bpm in preeclampsia (P<.001) but not in gestational hypertension.

CONCLUSION

Arterial stiffness is increased in women with hypertensive disorders of pregnancy compared with normotensive controls. In preeclampsia, vascular stiffness was significantly improved by antihypertensive treatment with alpha methyldopa, but remained higher than in normotensive controls.

Pulse wave analysis: a preliminary study of a novel technique for the prediction of pre-eclampsia

OBJECTIVE

To investigate whether first-trimester arterial pulse wave analysis (PWA) can predict pre-eclampsia.

DESIGN

This was a prospective screening study.

SETTING

The Homerton University Hospital, a London teaching hospital.

POPULATION

Two hundred and ten low-risk women with a singleton pregnancy were analysed.

METHODS

Radial artery pulse waveforms were measured between the 11(+0) and 13(+6) weeks of gestation and the aortic waveform derived by applying a generalised transfer function. Augmentation pressure (AP) and augmentation index at heart rate of 75 beats per minute (AIx-75), measures of arterial stiffness, were calculated. The multiple of the gestation-specific median in controls for AP and AIx-75 were calculated. Logistic regression models were developed and their predictive ability assessed using the area under the receiver operator curve.

MAIN OUTCOME MEASURES

Prediction of pre-eclampsia by AIx-75.

RESULTS

Fourteen (6.7%) women developed pre-eclampsia, and 196 remained normotensive. Eight of the 14 women developed pre-eclampsia before 34 weeks of gestation (early-onset pre-eclampsia). For a false-positive rate of 11%, AIx-75 had a detection rate of 79% for all cases of pre-eclampsia and 88% for early-onset pre-eclampsia.

CONCLUSION

First-trimester arterial PWA can play a significant role in understanding the pathophysiology of pre-eclampsia and may play a role in early screening.

The effect of obesity on heart rate (heart period) and physiologic parameters during pregnancy

Obesity and excess gestational weight gain (EGWG) in pregnancy increase the risk for adverse maternal and infant outcomes. Along with careful monitoring of weight gain during pregnancy, early identification of a maladaptive response to the changes of pregnancy may help to avoid adverse outcomes. Simple physiologic markers such as resting heart rate (HR), heart period (HP), and blood pressure (BP) may be powerful predictors of cardiovascular adaptation to pregnancy. This article summarizes the current state of the science regarding the effect of obesity (body mass index [BMI] > or =30 kg/m(2)) and EGWG in pregnant women at rest in laboratory settings. The impact of differences in weight gain (kg and BMI) on pregnancy outcomes is also examined. A search was conducted for articles published from 1985 to 2006 reporting data on body weight and HR or HP at rest from randomized controlled trials or controlled trials conducted in laboratory settings involving pregnant women at low or high risk for adverse pregnancy outcomes who were obese or had EGWG. A meta-analysis was conducted on the 23 studies meeting inclusion criteria to explore the relation of BMI to HR, HP, and physiologic parameters. Autonomic responsiveness was found to be diminished in obese women with a BMI > 30 kg/m(2) and in women with high risk for adverse pregnancy outcomes, which may indicate a maladaptive autonomic response that is imbalanced and disorganized and that reduces adaptation to environmental demands.

Profound impact of uncomplicated pregnancy on diastolic, but not systolic pulse contour of aortic pressure

OBJECTIVE

To evaluate the impact of uncomplicated pregnancy on the pulse contour of central aortic pressure.

METHODS

A total of 66 women with singleton pregnancy were grouped according to pregnancy duration: first trimester (T1, n = 22), second trimester (T2, n = 20), and third trimester (T3, n = 24). Non-pregnant healthy women, who took combined oral contraception, were included as controls (C, n = 21). The pulse contour of aortic pressure was obtained with radial applanation tonometry, using a commercial device (SphygmoCor). The influence of reflected waves on the contour was evaluated not only in systole, as usual with pulse contour analysis (systolic augmentation), but also in diastole (diastolic augmentation).

RESULTS

Throughout pregnancy, central systolic and diastolic blood pressure remained unchanged and comparable to values in the non-pregnant state. Systolic augmentation amounted to 8.1 +/- 7.5% of pulse pressure in the control group (mean +/- SD), and there was no statistically significant deviation from this value at any stage of pregnancy (T1, 4.6 +/- 11.4%; T2, 5.0 +/- 9.3%; T3, 4.7 +/- 8.1%). In contrast, the amplitude of the diastolic augmentation wave progressively declined with advancing pregnancy (C, 6.5 +/- 2.4%; T1, 5.2 +/- 3.1%; T2, 3.8 +/- 2.6%; P = 0.002 versus C, T3, 2.3 +/- 2.0%; P < 0.0001 versus C and P = 0.0004 versus T1).

CONCLUSION

The systolic shape of the central aortic pressure contour is left unaltered by pregnancy, implying a finely tuned adaptation of the cardiovascular system to the increased demand for blood flow at all stages of the gravid state. In contrast, the amplitude of reflection waves reaching the aortic root in diastole progressively decreases with advancing pregnancy.

Peripheral arterial pulse wave analysis in women with pre-eclampsia and gestational hypertension

OBJECTIVE

To compare peripheral pulse pressure waveforms in normal pregnancy, gestational hypertension (GH) and pre-eclampsia (PE).

DESIGN

Comparative study.

SETTING

Tertiary referral teaching hospital.

SAMPLE

Women with hypertensive disease in pregnancy and matched normal pregnant controls.

METHODS

Women in the third trimester of pregnancy with newly developed PE (n= 27) or GH (n= 33) were studied by radial artery applanation tonometry. Values were compared with those for gestational age matched normal pregnant women (n= 39).

MAIN OUTCOME MEASURES

Augmentation Index.

RESULTS

Hypertension was of equal severity in PE and GH. Central augmentation pressure and augmentation index, indicating vasoconstriction, were mildly elevated in GH, but markedly elevated in PE.

CONCLUSION

Non-invasive applanation tonometry discriminates among normal pregnancy, GH and PE, and may be useful to predict PE.

Maternal psychophysiological change during the second half of gestation

This study investigated the trajectory of physiological and psychological functioning during the second half of pregnancy and compared responsiveness to a laboratory stressor between pregnant and non-pregnant women. Monitoring of 137 pregnant women at 20, 24, 28, 32, 36, and 38 weeks of pregnancy included measures of heart period (HP), heart period variability (HPV), skin conductance (SCL), respiratory period (RP), respiratory sinus arrhythmia (RSA), and self-report of mood disturbance. HP and RSA declined during this period; SCL and mood disturbance increased. Parity was a significant moderator. HP and SCL responsiveness to the Stroop color-word task was assessed twice in pregnant participants and compared to a sample of 27 non-pregnant women. Physiologic responsiveness was reduced in pregnant women. Pregnant women perceived the Stroop to be more difficult, but performance was unaffected. Despite buffered responsivity to stressful stimuli during pregnancy, advancing gestation is associated with escalating sympathetic tone and declining parasympathetic tone.