The Influence of Pregnancy on Arterial Compliance

Gestational - age - specific reference intervals for blood pressure in normal pregnancy in a Southern Chinese population

OBJECTIVE

Physiological blood pressure changes in pregnancy are insufficiently defined. This paper describes the blood pressure changes across healthy pregnancies in a Southern Chinese population to present gestational - age - specific blood pressure ranges with smoothed centiles (3rd, 10th, 50th, 90th, and 97th).

METHODS

Antenatal blood pressure measurements [median (interquartile range) 9 (8 - 10) per woman] were repeated in 17, 776 women from a Southern China population. Multilevel cubic splines models were used to derive longitudinal reference ranges for systolic blood pressure (SBP) and diastolic blood pressure (DBP) from 6 to 42 weeks of gestation for the normal pregnancies (excluding chronic hypertension, preeclampsia, diabetic ones, and preterm birth et al.).

RESULTS

Systolic and diastolic BP increased from 6 weeks of gestation: 50th centile (3rd - 97th centile) 106 (87 - 125); 61 (47 - 77) mm Hg to 12 weeks of gestation: 50th centile (3rd - 97th centile) 108 (88 - 129); 64 (49 - 81) mm Hg. Then, the lowest value of 107 (87 - 129); 62 (47 - 78) mm Hg was reached at 16 weeks and 20 weeks of gestation, respectively. Systolic and diastolic BP then rose to a maximum median (3rd - 97th centile) of 115 (96 - 135); 68 (53 - 85) mm Hg at 42 weeks of gestation. Additionally, the ascending tendency of SBP after 16 weeks of gestation was interrupted by two fluctuations that occurred at 24 weeks and 30 weeks of gestation.

CONCLUSIONS

In summary, our study provides blood pressure reference values for Southern Chinese women with normal pregnancies. To identify gestational hypertension and hypotension, centiles for gestational - age - specific BP should be defined in healthy pregnancies. Understanding these changes in low risk pregnancies is essential to optimize maternal blood pressure management.

Subclinical Metabolic and Cardiovascular Factors and Brain White Matter Microstructural Integrity in Young Women

Women who have experienced pregnancy complications, specifically preeclampsia and gestational diabetes, have well documented increased risks of cardiovascular, metabolic, and neurological disease later in life. This study examined how specific cardiovascular and metabolic risk factors for preeclampsia assessed in a non-pregnant state were associated with brain white matter microstructural integrity. This study examined sixty-two healthy women (mean age 31 ± 5 years) who received metabolic and cardiovascular assessments as well as multiple modality MRI imaging. Participants were either nulliparous (n = 31) or had a history of preterm preeclampsia (n = 31). Imaging included acquisition Diffusion Tensor Imaging (DTI) to assess white matter integrity within the brain. We hypothesized that healthy, young, non-pregnant women with cardiovascular and metabolic profiles suggesting elevated risk would have decreased white matter integrity, represented by lower Fractional Anisotropy (FA) and increased Mean Diffusivity (MD) estimates in the posterior cortical areas of the brain. We observed increased white matter degradation (lower FA and increased MD) in posterior and occipital tracts, commissural fibers, and subcortical structures in women with increased adiposity, worse measures of cardiovascular and metabolic function, including greater insulin resistance (HOMA-IR), hyperlipidemia, elevated blood pressure, and increased arterial stiffness. The relationships detected between subclinical cardiovascular and metabolic phenotypes and increased white matter disruption at a young age, outside of pregnancy, are indicative that adverse changes are detectable long before cognitive clinical presentation. This may suggest that many of the long-term cardiovascular and metabolic risks of aging are influenced by physiologic aging trajectories rather than damage caused by pregnancy complications.

Prepregnancy physiology and subsequent preterm preeclampsia

BACKGROUND

Preeclampsia is a common pregnancy complication with debated etiology.

OBJECTIVE

To evaluate the contribution of prepregnancy physiology, biochemistry, and anthropometrics to the subsequent development of preterm preeclampsia.

STUDY DESIGN

One hundred twenty-four participants were recruited through open recruitment and targeted mailings. Participants included 81 nulliparous women and 43 with a history of preterm preeclampsia. We characterized cardiovascular function, metabolic profile, and body composition in 100 nonpregnant women who went on to subsequent pregnancy. Measures included plasma volume, baseline cardiovascular function and cardiovascular response to volume challenge, body composition, and circulating biochemical measures. Pregnancy outcome was obtained through chart review. Prepregnancy metrics for women who developed preterm preeclampsia were compared with measurements for those who did not, with adjustment for a history of prior preterm preeclampsia. Logistic regression modeling was used to identify the strongest prepregnancy factors associated with preterm preeclampsia.

RESULTS

Pregnancy outcomes included 11 women with preterm preeclampsia, 7 women with term preeclampsia, 20 women with other hypertension affecting their pregnancy, and 62 with uncomplicated pregnancies. We observed no difference in maternal age, study cycle day, lean body mass, uterine hemodynamics, or flow-mediated dilation across groups. Women with preterm preeclampsia had greater android fat content 3215±1143 vs 1918±1510 g (P=.002), faster supine pulse, 77±7 vs 67±10 beats per minute (P=.001), higher supine diastolic blood pressure 82±6 vs 68±6 mmHg (P<.001), increased cardiac output 5.6±1.1 vs 4.6±1 L/min (P=.002), faster aortic-popliteal pulse wave velocity 4.5±0.7 vs 3.8±0.5 m/sec (P<.001), and exaggerated cardiac output response to volume challenge 20±9 vs 9±12 L/min (P=.002) compared to those with other pregnancy outcomes. Women who developed preterm preeclampsia also had reduced renal vascular resistance index 0.86±0.08 vs 0.97±0.12 (P=.005) compared with other pregnancy outcomes when assessed prior to pregnancy. Women with subsequent preterm preeclampsia had higher serum c-reactive protein 10.7±12.5 vs 4.1±5.8 mg/mL (P=.003) and greater insulin resistance, as assessed by Homeostatic Model Assessment for Insulin Resistance calculation 2.2±1.1 vs 1.2±0.9 (P<.001).

CONCLUSION

Prepregnancy physiology is linked to subsequent preterm preeclampsia. The same factors associated with metabolic syndrome are more prominent in patients who develop preterm preeclampsia than those who do not, including increased vessel stiffness, low vascular compliance, high cardiac output, reduced renal vascular resistance index, insulin resistance, and increased android fat, all consistent with subclinical features of the metabolic syndrome.

Longitudinal blood pressure patterns of women with hypertensive disorders of pregnancy: preconception through postpartum

OBJECTIVE

To investigate the longitudinal blood pressure (BP) pattern of women with hypertensive disorders of pregnancy (HDP) preconception through the postpartum day (PPD) 42.

STUDY DESIGN

A retrospective study of women (≥15 years old) diagnosed with an HDP antenatally or postpartum, who were enrolled prospectively in a postpartum remote BP monitoring program between 3/2017 and 5/2020. BPs were collected from 47-time points: preconception, each trimester, delivery day, and 42 days postpartum. Analysis was conducted utilizing a mixed-effects longitudinal model.

MAIN OUTCOME MEASURES

Primary outcome was the longitudinal BP patterns. Secondary outcomes were the timing of BP stabilization (BPs < 140/90 mmHg for ≥48 h) and resolution (stabilized without antihypertensive medication use).

RESULTS

Our final analysis included 897 of the 964 eligible women. The peak systolic and diastolic BPs were on PPDs 3, 4, 5, and 5, 6, 7, respectively. Systolic BP fell below the preconception level after PPD15; diastolic BP reached its plateau after PPD17 and remained above the preconception level till PPD42 (p < .001). Postpartum BP peaked with the highest percentage of BP spikes on PPDs 4-7. The median survival times to BP stabilization and resolution were PPDs 11 (95% CI: 10-12) and 23 (95% CI: 21-25), respectively. By PPD42, 91.0% and 74.1% of women achieved BP stabilization and resolution, respectively.

CONCLUSION

This study data could be used to develop evidence-based recommendations for women with an HDP. Diastolic BPs remaining significantly higher than the preconception level indicates the long-term risk of cardiovascular disease. In our cohort, 26% of women had unresolved hypertension by PPD42, which reinforces the necessity to ensure long-term follow-up.

Postpartum Persistence of Maternal Uterine Vascular Gestational Adaptation in Rodents

Although pregnancy has long-lasting consequences for maternal vascular health, little is known about vascular changes postpartum (PP). Focusing on the uterine circulation, which undergoes unique structural and functional adaptation during gestation, we hypothesized that most pregnancy-induced changes would return to baseline PP, with minimal hysteresis. Large (main; MUA) and small (segmental; SUA) uterine arteries from adult Sprague Dawley rats (n = 42) were evaluated 1 and 4 weeks PP (1PP, 4PP) and compared with those of late-pregnant (LP, day 21) and age-matched non-pregnant (NP) animals. Some comparisons were extended to mesenteric arteries to evaluate differences between reproductive and systemic vessels. Pregnancy-induced axial elongation regressed > 80% 1PP in MUAs and SUAs, although some minimal hysteresis remained 4PP. Circumferential growth was slower to regress, with no reductions in lumen diameter or media thickness 1PP; values returned to (MUA) or approached (SUA) NP values by 4PP. Changes in vascular smooth muscle cell cross-sectional area-a measure of hypertrophy-paralleled those in lumen diameter. Mesenteric and uterine artery compliance diverged during gestation, and continued to do so PP. Decreased MUA compliance 4PP was supported by an increased collagen:elastin ratio. Adrenergic sensitivity increased in uterine, and decreased in mesenteric arteries during pregnancy, and returned to NP values 4PP in both types of vessels. MUA α-1 adrenoceptor expression tracked along with sensitivity. Thus, postpartum adaptation varies by both parameter and vessel type. While many parameters regressed postpartum, alterations in compliance did not, suggesting that matrix changes may have long-term consequences for maternal vascular function and health.

Interpregnancy interval, maternal age, and offspring's BMI and blood pressure at 7 years of age

Interpregnancy interval and maternal age are associated with birth outcomes. However, it is unknown regarding their long-term effects on child health. We aim to assess the associations between interpregnancy interval and offspring’s body mass index (BMI) and blood pressure (BP) at age of 7 years and to examine the role of maternal age in the associations. A secondary analysis was performed among 2604 mother-infant pairs in the prospective National Collaborative Perinatal Project, in which the children were followed up until 7 yrs of age. Interpregnancy interval was positively associated with offspring’s diastolic BP at 7 yrs (β = 0.053, 95% CI: 0.004–0.102) after adjusting for maternal and perinatal characteristics, feeding pattern, rapid weight gain in the first year of life, and current BMI z score and height z score. The inclusion of maternal age in the model did not change the effect size. Maternal age was independently associated with offspring’s BMI z score at 7 yrs (β = 0.014, 95% CI: 0.001–0.027). An interaction between interpregnancy interval and maternal age was present in the association with diastolic BP (P = 0.019), and the increasing maternal age aggravated the effects of long interpregnancy interval. Our finding suggests long interpregnancy interval is a risk factor for higher diastolic BP of the offspring. Increasing maternal age could amplify the impact. Our study challenges the current WHO recommendation for ideal interpregnancy interval, and we would suggest lowering the recommendation to <24 months and even shorter for women of advanced age.

Effect of Pregnancy Interval on Second Pregnancy Blood Pressure Following Prior Preeclampsia

OBJECTIVE

Preeclampsia generally occurs in first pregnancies and tends not to recur when the interpregnancy interval (IPI) is short. We hypothesized that, in women experiencing preeclampsia in their first pregnancy, the difference in mean arterial pressure (MAP) across pregnancy between their index and subsequent pregnancy would be inversely associated with the length of time between pregnancies and that the interval between pregnancies will be directly associated with the likelihood of preeclampsia recurrence.

METHODS

This was a retrospective chart review evaluating 171 women diagnosed with preeclampsia during their first pregnancy who had a subsequent pregnancy at our institution. Blood pressures were collected from each pregnancy, marking the recurrence of hypertensive disorders, including preeclampsia. Antepartum MAP was compared between pregnancies, examining differences as a function of IPI.

RESULTS

There was a significant association of IPI with the reduction in MAP between pregnancies across trimesters ( P = .04), but this reduction became smaller over time. The MAP during the third trimester decreased significantly between pregnancies across all patient groups (IPI <24 months: -5.7 mm Hg, P < .0001; IPI 24-48 months: -4.5 mm Hg, P < .0001; IPI >48 months -3.4 mm Hg, P = .03). The recurrence rate of preeclampsia did not vary significantly with IPI ( P = .21).

CONCLUSION

The IPI influences the MAP of the second pregnancy in women with prior preeclampsia. Shorter IPI is associated with a greater reduction in MAP when compared to the longer IPI. Although there was a trend toward higher preeclampsia recurrence with longer IPI, this trend did not reach statistical significance.

Endothelial dysfunction and vascular stiffness in women with previous pregnancy complicated by early or late pre-eclampsia

OBJECTIVES

Pre-eclampsia (PE) is associated with an increased cardiovascular risk later in life. The persistence of endothelial dysfunction after delivery may represent the link between PE and cardiovascular disease. We aimed to evaluate endothelial function and arterial stiffness after delivery of pregnancy complicated by early-onset (EO) or late-onset (LO) PE and their correlation with gestational age and mean uterine artery pulsatility index at PE diagnosis and birth-weight percentile.

METHODS

The study included 30 women with previous EO-PE, 30 with previous LO-PE and 30 controls with no previous PE. Participants were examined at between 6 months and 4 years after delivery. All included women were free from cardiovascular risk factors and drugs. Data on demographic and clinical characteristics during pregnancy were collected retrospectively from obstetrical charts. Endothelial function and arterial stiffness were assessed by peripheral arterial tonometry and pulse-wave analysis.

RESULTS

All vascular parameters were significantly different, indicating circulatory impairment, in women with previous EO-PE. Women with previous LO-PE had higher vascular rigidity than did controls and all had normal values of reactive hyperemia index, although they were significantly lower when compared with those of controls. On multivariate analysis, gestational age and mean uterine artery pulsatility index at the time of PE diagnosis, and birth-weight percentile were all statistically related to the vascular indices studied, after correcting for confounding parameters.

CONCLUSIONS

Women with previous pregnancy complicated by PE, in particular those with early-onset disease, showed persistent microcirculatory dysfunction, as suggested by a significant reduction in reactive hyperemia index value, and increased arterial stiffness. Copyright © 2016 ISUOG. Published by John Wiley & Sons Ltd.

Differences in cardiovascular function comparing prior preeclamptics with nulliparous controls

OBJECTIVE

The objective of the current study was to evaluate cardiovascular function; including blood pressure, cardiac output, pulse wave velocity and vascular compliance in nonpregnant nulliparous women compared to women with a history of preterm preeclampsia.

STUDY DESIGN

This was a case control study. Blood pressure was measured using the Finapres Pro. Baseline cardiac output was determined by echocardiography. Pulse wave velocity was estimated using simultaneous electrocardiographic tracings and ultrasound determined arterial flow waveforms and calculated as estimated distance divided by the time interval between EKG r-wave peak and ultrasound derived peak popliteal artery flow. During volume challenge, 500mL of lactated Ringers solution was infused through an indwelling antecubital catheter over 10min. Cardiac output and blood pressure during and 15min after the infusion were estimated using the Finapres Pro.

MAIN OUTCOME MEASURES

Indices of arterial stiffness and vascular compliance.

RESULTS

Previous preeclamptics exhibited a significant increase in pulse pressure and cardiac output in response to volume challenge when compared with nulliparous controls. Prior preeclamptics had a strong positive correlation between blood pressure indices (r=0.50-0.68, p⩽0.01) and pulse pressure (r=0.58, P=0.008) with pulse wave velocity that was not evident in control women.

CONCLUSIONS

In women with prior preterm preeclampsia a relationship between blood pressure, intravascular volume and arterial stiffness, is evident in the nonpregnant state and in the absence of hypertension or overt cardiovascular disease. This supports an overarching hypothesis that nonpregnant physiology is an important contributor to pregnancy adaptations.

Pregnancy induces persistent changes in vascular compliance in primiparous women

OBJECTIVE

Pregnancy induces rapid, progressive, and substantial changes to the cardiovascular system. The low recurrence risk of preeclampsia, despite familial predisposition, suggests an adaptation associated with pregnancy that attenuates the risk for subsequent preeclampsia. We aimed to evaluate the persistent effect of pregnancy on maternal cardiovascular physiology.

STUDY DESIGN

Forty-five healthy nulliparous women underwent baseline cardiovascular assessment before conception and repeated an average of 30 months later. After baseline evaluation, 17 women conceived singleton pregnancies and all delivered at term. The remaining 28 women comprised the nonpregnant control group. We measured mean arterial blood pressure, cardiac output, plasma volume, pulse wave velocity, uterine blood flow, and flow-mediated vasodilation at each visit.

RESULTS

There was a significant decrease in mean arterial pressure from the prepregnancy visit to postpartum in women with an interval pregnancy (prepregnancy, 85.3±1.8; postpartum, 80.5±1.8 mm Hg), with no change in nonpregnant control subjects (visit 1, 80.3±1.4; visit 2, 82.8±1.4 mm Hg) (P=.002). Pulse wave velocity was significantly decreased in women with an interval pregnancy (prepregnancy, 2.73±0.05; postpartum, 2.49±0.05 m/s), as compared with those without an interval pregnancy (visit 1, 2.56±0.04; visit 2, 2.50±0.04 m/s) (P=.005). We did not observe a residual effect of pregnancy on cardiac output, plasma volume, uterine blood flow, or flow-mediated vasodilation.

CONCLUSION

Our observations of decreased mean arterial pressure and reduced arterial stiffness following pregnancy suggest a significant favorable effect of pregnancy on maternal cardiovascular remodeling. These findings may represent a mechanism by which preeclampsia risk is reduced in subsequent pregnancies.

Preeclampsia and maternal cardiovascular disease: consequence or predisposition?

Formerly preeclamptic women stand a higher chance of developing cardiovascular disease (CVD) later in life and may experience a shortened life span. This review updates the pathophysiology and definition of this complex disease and highlights the protective role of pregnancy by considering the relationship between pregnancy interval and likelihood of disease recurrence. The evidence for persistent maternal cardiovascular impairment following preeclampsia (PE) is considered, e.g. postpartum changes in CVD occurrence, blood pressure elevation and changes in the renin-angiotensin-aldosterone system). Since maternal endothelial dysfunction is a hallmark of PE, we summarize the evidence for reduced flow-mediated dilation in women with previous PE, and consider the utility and shortcomings of this clinical measure. In addition to viewing postpartum changes as a consequence of this disease, we consider the alternative view that PE might be the manifestation of a maternal phenotype that already has some predisposition to or is in the earlier stages of CVD; in this case, some of the postpartum residual deficits (or their antecedents) may have already been present prior to pregnancy. Finally, we consider the use of novel biomarkers for predicting or detecting PE prior to the appearance of clinical symptoms.

Systemic arterial response and ventriculo-arterial interaction during normal pregnancy

BACKGROUND

During normal pregnancy (NP), cardiac output (CO) increases, and blood pressure and systemic vascular resistance are reduced. We wanted to evaluate systemic arterial properties and interaction between the left ventricle (LV) and systemic arteries during NP. The role of systemic arteries and their interaction with LV-function in this hemodynamic response, lack description.

METHODS

We used noninvasive methods to study 65 healthy women (32 ± 5 years) with NP repeatedly at gestational weeks 14-16, 22-24, 36, and 6 months postpartum (PP). Aortic root pressure and flow were obtained by calibrated right subclavian artery pulse traces and aortic annular Doppler flow recordings. Arterial properties were described by estimates of total arterial compliance (C), proximal aortic stiffness (characteristic impedance (Z(0))), arterial elastance (Ea), and peripheral arterial resistance (R). Ventriculo-arterial coupling (VAC) was characterized by the ratio between arterial (E(a)I) and LV (E(LV)I) elastance index.

RESULTS

During NP, CO increased by 20% due to increased heart rate and stroke volume. Mean arterial pressure was reduced by 10% (P < 0.001) as compared to 6 months PP. R was reduced by 5% (P < 0.01), Z(0) trended lower and C higher. E(a)I decreased (P < 0.01) and E(LV)I was reduced to a higher extent resulting in 29% increase of E(a)I/E(LV)I during NP (P < 0.01).

CONCLUSIONS

During NP there is an increase in CO, and decrease in blood pressure and R whereas central aortic properties are less altered. The increased VAC index (E(a)I/E(LV)I) during NP indicates a decrease in LV-function not fully compensated for by vascular adaptation.

Pulse pressure and arterial compliance prior to pregnancy and the development of complicated hypertension during pregnancy

We examined the relationship between prepregnant pulse pressure (PP), mean arterial pressure (MAP), cardiac output (CO)/PP, a measure of arterial compliance, and development of complicated hypertension (CH) during pregnancy with the goal of identifying a potential predictor of CH. Twenty nulliparous participants were studied before pregnancy; 17 had normal pregnancies (control; CTL) and 3 CH. Blood pressure monitoring was performed using tonometry. Cardiac output was determined by Doppler echocardiograph. Data are expressed as mean +/- SD. Prepregnant PP was significantly higher in CH participants (CH: 58.3 +/- 6.3, CTL: 46.2 +/- 1.7 mm Hg; P = .02). Cardiac output /pulse pressure was significantly lower in CH participants (CH: 6.9 +/- 1.8, CTL: 10.6 +/- 2.8; P = .04). Mean arterial pressure was not significantly different. Increased PP before pregnancy may suggest increased risk for CH. With accurate prediction of CH before pregnancy, initiation of preventative measures could begin earlier, either prior to or in early pregnancy, potentially increasing preventative efficacy and decreasing CH.

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.

Long-term blood pressure changes measured from before to after pregnancy relative to nonparous women

OBJECTIVE

To prospectively examine whether blood pressure changes persist after pregnancy among women of reproductive age.

METHODS

This was a prospective, population-based, observational cohort of 2,304 (1,167 black, 1,137 white) women (aged 18-30 years) who were free of hypertension at baseline (1985-1986) and reexamined up to six times at 2, 5, 7, 10, or 20 years later (2005-2006). We obtained standardized blood pressure measurements before and after pregnancies and categorized women into time-dependent groups by the cumulative number of births since baseline within each time interval (zero births [referent]; one interim birth and two or more interim births; nonhypertensive pregnancies). The study assessed differences in systolic and diastolic blood pressures among interim birth groups using multivariable, repeated measures linear regression models stratified by baseline parity (nulliparous and parous), adjusted for time, age, race, baseline covariates (blood pressure, body mass index, education, and oral contraceptive use), and follow-up covariates (smoking, antihypertensive medications, oral contraceptive use, and weight gain).

RESULTS

Among nulliparas at baseline, mean (95% confidence interval) fully adjusted systolic and diastolic blood pressures (mm Hg), respectively, were lower by -2.06 (-2.72 to -1.41) and -1.50 (-2.08 to -0.92) after one interim birth, and lower by -1.89 (-2.63 to -1.15) and -1.29 (-1.96 to -0.63) after two or more interim births compared with no births (all P<.001). Among women already parous at baseline, adjusted mean blood pressure changes did not differ by number of subsequent births.

CONCLUSION

A first birth is accompanied by persistent lowering of blood pressure from preconception to years after delivery. Although the biologic mechanism is unclear, pregnancy may create enduring alterations in vascular endothelial function.

LEVEL OF EVIDENCE

II.

Effects of interpregnancy interval on blood pressure in consecutive pregnancies

The lower risk of preeclampsia observed in parous women has prompted a hypothesis that cardiovascular adaptation from a first pregnancy has ongoing benefits which contribute to a reduced risk of preeclampsia in the second pregnancy. However, how the interpregnancy interval affects mean arterial pressure (MAP) as an indicator of cardiovascular adaptation in subsequent pregnancies has not been well studied. The authors examined the effect of interpregnancy interval on MAP in consecutive pregnancies using data from the Collaborative Perinatal Project (1959-1965) and a semiparametric random-effects regression model. Prenatal MAP measurements were available for 533 women with both first and second births. MAP was lower in the second pregnancy (by approximately 2 mmHg) for very short interpregnancy intervals. However, this difference diminished when the interval increased, and it totally disappeared for intervals longer than 2 years. The authors conclude that although MAP is lower in the second pregnancy than in the first pregnancy, the effect persists for only a short time. It is therefore unlikely that mechanisms involving MAP as an indicator of cardiovascular adaptation contribute appreciably to the reduced risk of preeclampsia in subsequent pregnancies. However, it does not rule out the possibility that other mechanisms of cardiovascular adaptation persist longer.

Pregnancy and adult congenital heart disease

Increasing numbers of women with complex congenital heart disease are reaching childbearing age. Pregnancy is a major issue in the management of adult congenital heart disease. Cardiac disease is one of the most common causes of maternal morbidity and mortality. Complications, such as growth retardation, preterm and premature birth and even fetal and neonatal mortality, are more frequent among children of women with congenital heart disease. The risk of complications is determined by the severity of the cardiac lesion, the presence of cyanosis, the maternal functional class and the use of anticoagulation. However, the pathophysiology of these complications is not completely understood and may be related to a diminished increase in cardiac output and/or endothelial dysfunction. The management of pregnant cardiac patients is based on limited clinical information. This article reviews pre-pregnancy counseling and management during pregnancy in patients with congenital heart disease.

HAEMODYNAMIC CONTRIBUTIONS TO THE PATHOGENESIS OF PREECLAMPSIA AND ECLAMPSIA

Current hypotheses regarding the origins of preeclampsia have focused on the “Two stage model”. This model suggests that the primary steps in the pathophysiologic sequence of preeclampsia are initiated by abnormal placentation including the classic finding of abnormal trophoblast invasion of maternal decidual spiral arteries. The second stage of the sequence includes the elaboration of a single or multiple substances from these disordered placentas which contribute to the generalized maternal systemic illness, eventually manifesting as endothelial injury, hypertension and proteinuria. Recent studies have focused on the role of pro and anti-angiogenic peptides as potential placentally derived aetiologic agents in this pathophysiologic sequence, although other placental products have been highlighted in recent research. Despite the fact that this modeling of preeclampsia has widespread support significant limitations to this hypothesis can be identified.

Why do women live longer than men?

Factors responsible for the gender difference in life-span being 4-5 years in favor of women were investigated. Cardiovascular risks are responsible for a five times higher mortality and three times higher morbidity in men compared with women. Genetics demonstrate marked gender differences in chromosomal constitution and female preponderance of the life-guard telomeres on chromosomes during mitotic cell division. This difference, however, cannot explain the gender gap fully. Endogenous estradiol - acting in picomoles - provokes marked cardiovascular changes. Cardiac output increases around 20% during the second half of the menstrual cycle and in pregnancy. This continuous biological challenge during the reproductive years creates optimal cardiovascular compliance comparable to the effects of exercise. The "jogging female heart" may explain the lower incidence of cardiovascular disease before menopause and the equalization after the menopause.