Effect of parity on maternal cardiac function during the first trimester of pregnancy

Pathophysiology of Pre-Eclampsia-Two Theories of the Development of the Disease

Pre-eclampsia (PE) continues to be a leading cause of maternal and fetal mortality and morbidity. While substantial progress has been made in understanding the pathomechanisms of PE, the pathophysiology of the disease is still not fully understood. While the "two-stage model" of the development of PE is the most widely accepted theory, stating that the placenta is the main source of the disease, there are some other pathophysiological models of PE. Among these other theories, the one considering heart dysfunction as serving as the primary cause of PE seems to be gaining increasing prominence. In this review, we aim to elucidate these two divergent concepts concerning the development of PE. Despite some differences in their proposed pathomechanisms, both theories share vital pathophysiological elements in common. A central and critical component in both models is impaired placental perfusion, which appears to be a crucial phenomenon in PE. A comprehensive understanding of the different pathomechanisms involved in PE may be helpful in clinical practice, prompting a more individual approach to care of patients with PE.

Characterizing the effect of demographics, cardiorespiratory factors, and inter-subject variation on maternal heart rate variability in pregnancy with statistical modeling: a retrospective observational analysis

Pregnancy complications are associated with insufficient adaptation of the maternal autonomic nervous system to the physiological demands of pregnancy. Consequently, assessing maternal heart rate variability (mHRV)-which reflects autonomic regulation-is a promising tool for detecting early deterioration in maternal health. However, before mHRV can be used to screen for complications, an understanding of the factors influencing mHRV during healthy pregnancy is needed. In this retrospective observational study, we develop regression models to unravel the effects of maternal demographics (age, body mass index (BMI), gestational age (GA), and parity), cardiorespiratory factors (heart rate and breathing rate), and inter-subject variation on mHRV. We develop these models using two datasets which are comprised of, respectively, single measurements in 290 healthy pregnant women and repeated measurements (median = 8) in 29 women with healthy pregnancies. Our most consequential finding is that between one-third and two-thirds of the variation in mHRV can be attributed to inter-subject variability. Additionally, median heart rate dominantly affects mHRV (p < 0.001), while BMI and parity have no effect. Moreover, we found that median breathing rate, age, and GA all impact mHRV (p < 0.05). These results suggest that personalized, long-term monitoring would be necessary for using mHRV for obstetric screening.

Sinus Tachycardia: a Multidisciplinary Expert Focused Review

Sinus tachycardia (ST) is ubiquitous, but its presence outside of normal physiological triggers in otherwise healthy individuals remains a commonly encountered phenomenon in medical practice. In many cases, ST can be readily explained by a current medical condition that precipitates an increase in the sinus rate, but ST at rest without physiological triggers may also represent a spectrum of normal. In other cases, ST may not have an easily explainable cause but may represent serious underlying pathology and can be associated with intolerable symptoms. The classification of ST, consideration of possible etiologies, as well as the decisions of when and how to intervene can be difficult. ST can be classified as secondary to a specific, usually treatable, medical condition (eg, pulmonary embolism, anemia, infection, or hyperthyroidism) or be related to several incompletely defined conditions (eg, inappropriate ST, postural tachycardia syndrome, mast cell disorder, or post-COVID syndrome). While cardiologists and cardiac electrophysiologists often evaluate patients with symptoms associated with persistent or paroxysmal ST, an optimal approach remains uncertain. Due to the many possible conditions associated with ST, and an overlap in medical specialists who see these patients, the inclusion of experts in different fields is essential for a more comprehensive understanding. This article is unique in that it was composed by international experts in Neurology, Psychology, Autonomic Medicine, Allergy and Immunology, Exercise Physiology, Pulmonology and Critical Care Medicine, Endocrinology, Cardiology, and Cardiac Electrophysiology in the hope that it will facilitate a more complete understanding and thereby result in the better care of patients with ST.

Maternal Low Volume Circulation Relates to Normotensive and Preeclamptic Fetal Growth Restriction

This narrative review summarizes current evidence on the association between maternal low volume circulation and poor fetal growth. Though much work has been devoted to the study of cardiac output and peripheral vascular resistance, a low intravascular volume may explain why high vascular resistance causes hypertension in women with preeclampsia (PE) that is associated with fetal growth restriction (FGR) and, at the same time, presents with normotension in FGR itself. Normotensive women with small for gestational age babies show normal gestational blood volume expansion superimposed upon a constitutionally low intravascular volume. Early onset preeclampsia (EPE; occurring before 32 weeks) is commonly associated with FGR, and poor plasma volume expandability may already be present before conception, thus preceding gestational volume expansion. Experimentally induced low plasma volume in rodents predisposes to poor fetal growth and interventions that enhance plasma volume expansion in FGR have shown beneficial effects on intrauterine fetal condition, prolongation of gestation and birth weight. This review makes the case for elevating the maternal intravascular volume with physical exercise with or without Nitric Oxide Donors in FGR and EPE, and evaluating its role as a potential target for prevention and/or management of these conditions.

The placenta and preeclampsia: villain or victim?

Preeclampsia is a disease whose characterization has not changed in the 150 years since the cluster of signs associated with the disorder were first described. Although our understanding of the pathophysiology of preeclampsia has advanced considerably since then, there is still little consensus regarding the true etiology of preeclampsia. As a consequence, preeclampsia has earned the moniker "disease of theories," predominantly because the underlying biological mechanisms linking clinical epidemiologic findings to observed organ dysfunction in preeclampsia are far from clear. Despite the lack of cohesive evidence, expert consensus favors the hypothesis that preeclampsia is a primary placental disorder. However, there is now emerging evidence that suboptimal maternal cardiovascular performance resulting in uteroplacental hypoperfusion is more likely to be the cause of secondary placental dysfunction in preeclampsia. Preeclampsia and cardiovascular disease share the same risk factors, preexisting cardiovascular disease is the strongest risk factor (chronic hypertension, congenital heart disease) for developing preeclampsia, and there are now abundant data from maternal echocardiography and angiogenic marker studies that cardiovascular dysfunction precedes the development of preeclampsia by several weeks or months. Importantly, cardiovascular signs and symptoms (hypertension, cerebral edema, cardiac dysfunction) predominate in preeclampsia at clinical presentation and persist into the postnatal period with a 30% risk of chronic hypertension in the decade after birth. Placental malperfusion caused by suboptimal maternal cardiovascular performance may lead to preeclampsia, thereby explaining the preponderance of cardiovascular drugs (aspirin, calcium, statins, metformin, and antihypertensives) in preeclampsia prevention strategies. Despite the seriousness of the maternal and fetal consequences, we are still developing sensitive screening, reliable diagnostic, effective therapeutic, or improvement strategies for postpartum maternal cardiovascular legacy in preeclampsia. The latter will only become clear with an acceptance and understanding of the cardiovascular etiology of preeclampsia.

Cardiac output and peripheral vascular resistance during normotensive and hypertensive pregnancy - a systematic review and meta-analysis

BACKGROUND

In-depth insight into haemodynamic changes during normotensive pregnancy may help identify women at risk for gestational hypertensive complications.

OBJECTIVES

To determine the magnitude of changes in cardiac output and its determinants stroke volume and heart rate, and total peripheral vascular resistance during singleton normotensive and hypertensive pregnancies.

SEARCH STRATEGY

PubMed (NCBI) and Embase (Ovid) databases were searched from their inception up to November 2019.

SELECTION CRITERIA

Studies reporting original measurements of haemodynamic parameters during pregnancy together with a non-pregnant reference measurement. Studies including women using antihypertensive medication were excluded.

DATA COLLECTION AND ANALYSIS

Pooled mean differences between pregnant and non-pregnant women, and absolute values of haemodynamic parameters were calculated for predefined gestational intervals using a random-effects model in normotensive and hypertensive pregnancy. Meta-regression analysis was used to analyse group differences in adjustments and absolute values during pregnancy.

MAIN RESULTS

In normotensive pregnancies, cardiac output increased from the first weeks on, reaching its highest level early in the third trimester (mean difference, 1.41 l·min¹ ; 95% CI 1.18-1.63 l·min^-1 ). In parallel, vascular resistance decreased progressively until its nadir in the early third trimester (mean difference, -331 dyn·sec^-1 ·cm^-5 ; 95% CI -384 to -277 dyn·sec^-1 ·cm^-5 ) and then increased slightly at term. In hypertensive pregnancies, the initial cardiac output increase was higher and vascular resistance did not change throughout gestation compared with reference values.

CONCLUSIONS

Hemodynamic changes in women who eventually develop hypertensive complications are substantially different. Serial monitoring and plotting against developed normograms can identify women at risk and may allow timely intervention.

TWEETABLE ABSTRACT

Monitoring haemodynamic changes in pregnancy helps identify women at risk for hypertensive complications.

Trends of blood pressure and heart rate in normal pregnancies: a systematic review and meta-analysis

BACKGROUND

Current reference ranges for blood pressure and heart rate throughout pregnancy have a poor evidence base.

METHODS

This is a systematic review and meta-analysis. We included studies measuring blood pressure or heart rate from healthy pregnant women within defined gestational periods of 16 weeks or less. We analysed systolic blood pressure, diastolic blood pressure and heart rate by gestational age. We assessed effects of measurement year and method.

RESULTS

We included 39 studies undertaken in 1967-2017, containing 124,349 systolic measurements from 36,239 women, 124,291 diastolic measurements from 36,181 women and 10,948 heart rate measurements from 8317 women. Mean (95% CI) systolic blood pressure was lowest at 10 weeks gestation, 110.4 (108.5, 112.3) mmHg, rising to 116.0 (113.6, 118.4) mmHg at 40 weeks, mean (95% CI) change 5.6 (4.0, 7.2) mmHg. Mean (95% CI) diastolic blood pressure was lowest at 21 weeks gestation, 65.9 (64.2, 67.7) mmHg; rising to 72.8 (71.0, 74.6) mmHg at 40 weeks, mean (95% CI) change 6.9 (6.2, 7.5) mmHg. Mean (95% CI) heart rate rose from 79.3 (75.5, 83.1) beats/min at 10 weeks to 86.9 (82.2, 91.6) beats/min at 40 weeks gestation, mean (95% CI) change 7.6 (1.8, 13.4) beats/min. Studies using manual measurement reported higher diastolic blood pressures than studies using automated measurement, mean (95 CI) difference 4.9 (0.8, 8.9) mmHg. Diastolic blood pressure increased by 0.26 (95% CI 0.10-0.43) mmHg/year. Including only higher-quality studies had little effect on findings, with heterogeneity remaining high (I2 statistic > 50%).

CONCLUSIONS

Significant gestational blood pressure and heart rate changes occur that should be taken into account when assessing pregnant women. Commonly taught substantial decreases in blood pressure mid-pregnancy were not seen and heart rate increases were lower than previously thought. Manual and automated blood pressure measurement cannot be used interchangeably. Increases in diastolic blood pressure over the last half-century and differences between published studies show contemporary data are required to define current normal ranges.

STUDY REGISTRATION

PROSPERO CRD42014009673.

The effect of parity on longitudinal maternal hemodynamics

BACKGROUND

Parous women have a lower risk for pregnancy complications, such as preeclampsia or delivery of small-for-gestational-age neonates. However, parous women are a heterogeneous group of patients because they contain a low-risk cohort with previously uncomplicated pregnancies and a high-risk cohort with previous pregnancies complicated by preeclampsia and/or small for gestational age. Previous studies examining the effect of parity on maternal hemodynamics, including cardiac output and peripheral vascular resistance, did not distinguish between parous women with and without a history of preeclampsia or small for gestational age and reported contradictory results.

OBJECTIVE

The objective of the study was to compare maternal hemodynamics in nulliparous women and in parous women with and without previous preeclampsia and/or small for gestational age.

STUDY DESIGN

This was a prospective, longitudinal study of maternal hemodynamics, assessed by a bioreactance method, measured at 11⁺⁰ to 13⁺⁶, 19⁺⁰ to 24⁺⁰, 30⁺⁰ to 34⁺⁰, and 35⁺⁰ to 37⁺⁰ weeks' gestation in 3 groups of women. Group 1 was composed of parous women without a history of preeclampsia and/or small for gestational age (n = 632), group 2 was composed of nulliparous women (n = 829), and group 3 was composed of parous women with a history of preeclampsia and/or small for gestational age (n = 113). A multilevel linear mixed-effects model was performed to compare the repeated measures of hemodynamic variables controlling for maternal characteristics, medical history, and development of preeclampsia or small for gestational age in the current pregnancy.

RESULTS

In groups 1 and 2, cardiac output increased with gestational age to a peak at 32 weeks and peripheral vascular resistance showed a reversed pattern with its nadir at 32 weeks; in group 1, compared with group 2, there was better cardiac adaptation, reflected in higher cardiac output and lower peripheral vascular resistance. In group 3 there was a hyperdynamic profile of higher cardiac output and lower peripheral vascular resistance at the first trimester followed by an earlier sharp decline of cardiac output and increase of peripheral vascular resistance from midgestation. The incidence of preeclampsia and small for gestational age was highest in group 3 and lowest in group 1.

CONCLUSION

There are parity-specific differences in maternal cardiac adaptation in pregnancy.

Preeclampsia: The Relationship between Uterine Artery Blood Flow and Trophoblast Function

Maternal uterine artery blood flow is critical to maintaining the intrauterine environment, permitting normal placental function, and supporting fetal growth. It has long been believed that inadequate transformation of the maternal uterine vasculature is a consequence of primary defective trophoblast invasion and leads to the development of preeclampsia. That early pregnancy maternal uterine artery perfusion is strongly associated with placental cellular function and behaviour has always been interpreted in this context. Consistently observed changes in pre-conceptual maternal and uterine artery blood flow, abdominal pregnancy implantation, and late pregnancy have been challenging this concept, and suggest that abnormal placental perfusion may result in trophoblast impairment, rather than the other way round. This review focuses on evidence that maternal cardiovascular function plays a significant role in the pathophysiology of preeclampsia.

Maternal parity and perinatal cortisol adaptation: The role of pregnancy-specific distress and implications for postpartum mood

INTRODUCTION

Compared to women who have given birth before (i.e., multiparas), those giving birth for the first time (i.e., primiparas) show higher cortisol levels. Psychological factors may play a role; hypothalamic-pituitary-adrenal activation is a well-described stress response. Primiparity also predicts greater risk for postpartum depression, which may be related to greater correspondence between cortisol and mood following prenatal cortisol elevations. The current study examined associations among parity, perinatal cortisol adaptation, pregnancy-specific distress, and postpartum mood.

METHODS

This longitudinal study assayed serum cortisol levels among 137 women at early, mid-, and late pregnancy and postpartum. Pregnancy-specific distress and depressive symptoms were assessed. Maternal age, race, body mass index, sleep quality, depressive symptoms, and sampling time of day were statistically controlled.

RESULTS

Primiparous women showed higher cortisol levels than multiparous women during mid- (χ² = 11.8, p < 0.01) and late pregnancy (χ² = 18.9, p < 0.01) and higher distress across pregnancy (F_1,126 = 22.1, p < 0.01). Mediation analyses demonstrated that the association between parity and prenatal cortisol (per area under the curve; AUC) was partially accounted for by distress (ab = 1.0, 95%CI [0.05, 2.9]). Prenatal cortisol (per AUC) did not predict postpartum depressive symptoms (b* = 0.03, p = 0.81), with no difference by parity (b* = 0.03, p = 0.91). At postpartum, a significant interaction between parity and cortisol (b* = 0.40, p = 0.03) revealed no significant association between cortisol and mood among multiparas (b* = -0.11, p = 0.28) but a trend toward a positive association among primiparas (b* = 0.24, p = 0.06).

DISCUSSION

Cortisol levels and pregnancy-specific distress are higher in primiparas versus multiparas, with pregnancy-specific distress partially mediating the association between parity and cortisol levels. Cortisol levels and mood display correspondence at postpartum in primiparous but not multiparous women. While observational studies must be interpreted with caution due to potential unmeasured confounders, these findings suggest that future studies examining mechanisms underlying perinatal and postpartum hypothalamic-pituitary-adrenal perturbations and designing interventions aimed at preventing related complications should carefully consider potential differences by parity.

Maternal cardiovascular function at 35-37 weeks' gestation: relation to maternal characteristics

OBJECTIVE

To examine the possible effects of maternal characteristics and obstetric and medical history on maternal cardiovascular parameters at 35-37 weeks' gestation.

METHODS

In 3013 singleton pregnancies at 35-37 weeks, maternal characteristics and medical history were recorded; uterine artery pulsatility index, mean arterial pressure (MAP) and maternal cardiovascular parameters were measured. Multivariable regression analysis was used to determine significant predictors of the cardiovascular parameters among gestational age (GA), maternal characteristics and medical history.

RESULTS

Multivariable regression analysis demonstrated that significant independent prediction of log₁₀ cardiac output and log₁₀ cardiac power was provided by GA, maternal age, weight, weight gain from the first trimester, height, racial origin, smoking, assisted conception and previous neonatal birth-weight Z-score in parous women. For log₁₀ total peripheral resistance, significant prediction was provided by GA, maternal age, height, racial origin, chronic hypertension, diabetes mellitus, assisted conception, previous neonatal birth-weight Z-score and prior pre-eclampsia (PE) in parous women. For log₁₀ stroke volume, significant prediction was provided by maternal age, height, racial origin, smoking, chronic hypertension and diabetes mellitus. For heart rate, significant prediction was provided by GA, weight, weight gain, height, racial origin, chronic hypertension, previous neonatal birth-weight Z-score and prior PE in parous women. For log₁₀ MAP, significant prediction was provided by maternal weight, racial origin, family history of PE, chronic hypertension and diabetes mellitus. For log₁₀ thoracic fluid capacity, significant prediction was provided by GA, maternal age, weight, height, racial origin and systemic lupus erythematosus or antiphospholipid syndrome. For log₁₀ ventricular ejection time, significant prediction was provided by GA, weight, height and racial origin.

CONCLUSION

Maternal cardiovascular parameters are affected by maternal characteristics and medical and obstetric history, and they should therefore be converted into multiples of the normal median adjusted for significant independent predictors before their inclusion in combined screening for PE. Copyright © 2016 ISUOG. Published by John Wiley & Sons Ltd.

Maternal ethnicity and its impact on the haemodynamic and blood pressure response to labetalol for the treatment of antenatal hypertension

Objective

Blood pressure (BP) control outside pregnancy is associated with a reduction in adverse cardiovascular events, and in pregnancy with improved outcomes. Outside pregnancy, there is evidence β-blockers are less effective in controlling BP in black populations. However, in pregnancy, labetalol is recommended as a universal first-line treatment, without evidence for the impact of ethnicity on its efficacy. We sought to compare haemodynamic responses to labetalol in black and white pregnant patients.

Methods

This was a prospective observational cohort study in a London teaching hospital. Maternal haemodynamics were assessed in 120 pregnant women treated with labetalol monotherapy. Measurements were taken at presentation, 1 and 24 h after treatment. Participants were monitored regularly until delivery. Statistical analysis was performed by multilevel modelling.

Results

Both groups exhibited similar temporal trends in haemodynamic changes over the first 24 h following labetalol. Both showed a reduction in BP and peripheral vascular resistance within 1 h and in heart rate after 24 h. There was no change in cardiac output and stroke volume in either group. BP control (<140/90) was achieved at 1 h in 79.7% of the white and 77% of the black cohort. At 24 h, control was achieved among 83.1% and 63.9%, and up to the immediate intrapartum period control was achieved in 89.8% and 70.4% of white and black patients, respectively.

Conclusions

There is no difference in the acute haemodynamic changes and hypertension can be controlled throughout pregnancy with labetalol monotherapy in excess of 70% pregnant black and white patients.

Maternal functional hemodynamics in the second half of pregnancy: a longitudinal study

Objective

Cardiovascular response to passive leg raising (PLR) is useful in assessing preload reserve, but it has not been studied longitudinally during pregnancy. We aimed to investigate gestational age associated serial changes in maternal functional hemodynamics and establish longitudinal reference ranges for the second half of pregnancy.

Materials and Methods

This was a prospective longitudinal study on 98 healthy pregnant women who were examined 3–5 times during 20–40 weeks of gestation (a total of 441 observations). Maternal cardiac function and systemic hemodynamics were assessed at baseline and 90 seconds after PLR using impedance cardiography (ICG). The main outcome measures were gestational age specific changes in ICG-derived variables of maternal cardiovascular function and functional hemodynamic response to PLR.

Results

Hemodynamic response to PLR varied during pregnancy. PLR led to an insignificant increase in stroke volume during 20⁺⁰ to 31⁺⁶ weeks, but later in gestation the stroke volume was slightly lower at PLR compared to baseline. PLR caused no significant change in cardiac output between 20⁺⁰ and 23⁺⁶ weeks and a significant decrease after 24⁺⁰ weeks. A decrease in heart rate, mean arterial pressure, and cardiac contractility was observed during PLR throughout the second half of pregnancy. Systemic vascular resistance was reduced by PLR up to 32⁺⁰ weeks, but increased slightly thereafter.

Conclusion

Healthy pregnant women appear to have limited preload reserve and reduced cardiac contractility, especially in the third trimester, which makes them vulnerable to fluid overload and cardiac failure.

Reference ranges for uterine artery pulsatility index during the menstrual cycle: a cross-sectional study

BACKGROUND

Cyclic endometrial neoangiogenesis contributes to changes in local vascular patterns and is amenable to non-invasive assessment with Doppler sonography. We hypothesize that the uterine artery (UtA) impedance, measured by its pulsatility index (PI), exhibits a regular pattern during the normal menstrual cycle. Therefore, the main study objective was to derive normative new day-cycle-based reference ranges for the UtA-PI during the entire cycle from days 1 to 34 according to the isolated time effect and potential confounders such as age and parity.

METHODS

From January 2009 to December 2012, a cross-sectional study of 1,821 healthy women undergoing routine gynaecological ultrasound was performed. The Doppler flow of the right and left UtA-PI was studied transvaginally by colour and pulsed Doppler imaging. The mean right and left values and the presence or absence of a bilateral protodiastolic notch were recorded. Reference intervals for the PI according to the cycle day were generated by classical linear regression.

RESULTS

The majority of patients (97.5%) presented unilateral or bilateral UtA notches. The crude 5th, 50th, and 95th reference percentile curves of the UtA-PI at 1-34 days of the normal menstrual cycle were derived. In all curves, a progressive significant decrease occurred during the first 13 days, followed by an increase and recovery in the UtA-PI. The adjusted 5th, 50th, and 95th reference percentile curves for the effects of age and parity were also obtained. These two conditions generated an approximately identical UtA-PI pattern during the cycle, except with small but significant reductions at the temporal extremes.

CONCLUSIONS

The median, 5th, and the 95th percentiles of the UtA-PI decrease during the first third of the menstrual cycle and recover to their initial values during the last two thirds of the cycle. The rates of decrease and recovery depend significantly on age and parity.

Hepatic hemodynamics and fetal growth: a relationship of interest for further research

BACKGROUND

It is well known that hepatic hemodynamics is an important physiologic mechanism in the regulation of cardiac output (CO). It has been reported that maternal cardiac output relates to neonatal weight at birth.

AIMS

In this study, we assessed the correlation between maternal hepatic vein Doppler flow parameters, cardiac output and neonatal birth weight.

METHODS

Healthy women with uncomplicated second or third trimester pregnancy attending the outpatient antenatal clinic of Ziekenhuis Oost-Limburg in Genk (Belgium), had a standardized combined electrocardiogram-Doppler ultrasound with Impedance Cardiography, for measurement of Hepatic Vein Impedance Index (HVI  =  [maximum velocity - minimum velocity]/maximum velocity), venous pulse transit time (VPTT  =  time interval between corresponding ECG and Doppler wave characteristics) and cardiac output (heart rate x stroke volume). After delivery, a population-specific birth weight chart, established from a cohort of 27000 neonates born in the index hospital, was used to define customized birth weight percentiles (BW%). Correlations between HVI, VPTT, CO and BW% were calculated using Spearman's ρ, linear regression analysis and R2 goodness of fit in SPSS 22.0.

RESULTS

A total of 73 women were included. There was a negative correlation between HVI and VPTT (ρ = -0.719, p < 0.001). Both HVI and VPTT correlated with CO (ρ = -0.403, p < 0.001 and ρ = 0.332, p < 0.004 resp.) and with BW% (ρ =  -0.341, p < 0.003 and ρ = 0.296, p < 0.011 resp.).

CONCLUSION

Our data illustrate that the known contribution of hepatic hemodynamics in the regulation of cardiac output is also true for women with uncomplicated pregnancies. Our study is the first to illustrate a potential link between maternal hepatic hemodynamics and neonatal birth weight. Whether this link is purely associative or whether hepatic vascular physiology has a direct impact on fetal growth is to be evaluated in more extensive clinical and experimental research.

Physiologic and pharmacokinetic changes in pregnancy

Physiologic changes in pregnancy induce profound alterations to the pharmacokinetic properties of many medications. These changes affect distribution, absorption, metabolism, and excretion of drugs, and thus may impact their pharmacodynamic properties during pregnancy. Pregnant women undergo several adaptations in many organ systems. Some adaptations are secondary to hormonal changes in pregnancy, while others occur to support the gravid woman and her developing fetus. Some of the changes in maternal physiology during pregnancy include, for example, increased maternal fat and total body water, decreased plasma protein concentrations, especially albumin, increased maternal blood volume, cardiac output, and blood flow to the kidneys and uteroplacental unit, and decreased blood pressure. The maternal blood volume expansion occurs at a larger proportion than the increase in red blood cell mass, which results in physiologic anemia and hemodilution. Other physiologic changes include increased tidal volume, partially compensated respiratory alkalosis, delayed gastric emptying and gastrointestinal motility, and altered activity of hepatic drug metabolizing enzymes. Understating these changes and their profound impact on the pharmacokinetic properties of drugs in pregnancy is essential to optimize maternal and fetal health.

Maternal cardiac metabolism in pregnancy

Pregnancy causes dramatic physiological changes in the expectant mother. The placenta, mostly foetal in origin, invades maternal uterine tissue early in pregnancy and unleashes a barrage of hormones and other factors. This foetal 'invasion' profoundly reprogrammes maternal physiology, affecting nearly every organ, including the heart and its metabolism. We briefly review here maternal systemic metabolic changes during pregnancy and cardiac metabolism in general. We then discuss changes in cardiac haemodynamic during pregnancy and review what is known about maternal cardiac metabolism during pregnancy. Lastly, we discuss cardiac diseases during pregnancy, including peripartum cardiomyopathy, and the potential contribution of aberrant cardiac metabolism to disease aetiology.

Variation by diagnostic subtype in risk for autism spectrum disorders associated with maternal parity among Finnish births

BACKGROUND

Associations between maternal parity and outcomes in offspring may provide evidence for involvement of prenatal exposures. The objective of this study was to determine whether risk for autism spectrum disorders (ASD) is associated with maternal parity.

METHODS

Diagnoses of childhood autism, Asperger syndrome, and pervasive developmental disorder, not otherwise specified (PDD-NOS) were examined separately and as a group. The study was conducted in the Finnish Prenatal Study of Autism, which is based in a national birth cohort. Children born in Finland in 1987-2005 and diagnosed with ASD by 2007 were identified through the Finnish Hospital Discharge Register. Four matched controls were selected for each case using the Finnish Medical Birth Register. The association between parity and each ASD was determined using conditional logistic regression and adjusted for number of children in the sibship and other potential confounders.

RESULTS

ASDs combined showed a pattern of decreasing risk with increasing parity (odds ratio OR for fourth or greater vs. first-born children, 0.43 [95% confidence interval (CI): 0.35, 0.51]). For childhood autism, an adjusted OR of 1.51 [95% CI 1.27, 1.81] was observed for second vs. first-born children. Associations for Asperger syndrome and PDD-NOS were consistent with those for all ASDs.

CONCLUSIONS

Differences in patterns of association between maternal parity and ASD subtypes may indicate varying contributions of specific environmental factors to risk; however, differences in diagnosis or in treatment seeking for childhood behavioural problems cannot be ruled out, particularly for higher functioning cases.

Cardiac structure and function in normal pregnancy

PURPOSE OF REVIEW

To review the published data on maternal cardiac adaptation to pregnancy.

RECENT FINDINGS

Normal pregnancy is characterized by significant changes in the cardiovascular system. Studies on systemic arterial system and heart remodelling in pregnancy provide somewhat uniform results. In normal pregnancy, left ventricle mass, cardiac output and arterial compliance increase, whereas total vascular resistance decreases. In contrast, findings on left ventricular systolic and diastolic chamber and myocardial function are conflicting.

SUMMARY

The major limitation of earlier studies on left ventricular systolic function is the use of ejection-phase indices that are dependent on loading conditions. Even when tissue Doppler velocity and deformation indices were measured, studies interpreted diastolic indices in isolation, rather than using validated diagnostic algorithms which account for the interdependency of cardiac events. Furthermore, the strong age-dependency of diastolic function indices was not accounted for in the majority of assessments and none of the studies diagnose or grade diastolic dysfunction. Future studies should aim to use appropriate control individuals, age-adjusted cutoff of cardiac diastolic indices and extended tissue Doppler velocity and deformation indices to provide objective information about chamber and myocardial function.

Hemodynamic adaptations in different trimesters among nulliparous and multiparous pregnant women; the Generation R study

BACKGROUND

It has been suggested that maternal vascular adaptations during pregnancy differ between nulliparous and multiparous women. Therefore, we examined the associations of parity with blood pressure and hemodynamic placental function during pregnancy and risks of gestational hypertensive disorders.

METHODS

The study was embedded in a population-based prospective cohort study among 8,377 pregnant women. Information about parity and gravidity was obtained at enrollment. Blood pressure was repeatedly measured in each trimester and mean pulsatility and resistance indexes of uterine artery were measured in second and third trimesters. Information on gestational hypertension and preeclampsia was available from medical records.

RESULTS

As compared with nulliparous women, multiparous women had a lower systolic and diastolic blood pressure in each trimester of pregnancy and a slightly higher second and third trimester uterine artery resistance and pulsatility indexes (all P values < 0.05), but a lower risk of third trimester uterine artery notching (odds ratio (OR) 0.67 (95% confidence interval (CI):0.53, 0.84)). The risks of gestational hypertension and preeclampsia were lower among multiparous women as compared with nulliparous women (OR 0.32 (95% CI: 0.24, 0.43) and OR 0.24 (95% CI: 0.16, 0.37), respectively). Among multiparous women only, we did not observe associations of parity with hemodynamic parameters.

CONCLUSIONS

Nulliparous pregnant women have higher blood pressure levels throughout pregnancy and higher risks of notching and gestational hypertensive disorders. The first pregnancy might be a major risk factor for maternal hemodynamic maladaptations and vascular complications. Further studies are needed to explore the underlying mechanisms and consequences for fetal growth and development.

Tissue factor-dependent thrombin generation across pregnancy

OBJECTIVE

Normal pregnancy results in a prothrombotic state. Studies that have investigated the capacity of pregnant women to generate thrombin are limited. Our aim was to evaluate thrombin generation longitudinally from the preconception period, through pregnancy, and after pregnancy.

STUDY DESIGN

We evaluated young, healthy nulligravid women (n = 20) at 4 time points and compared the data with 10 control women at 2 time points. Coagulation was initiated with tissue factor in contact pathway inhibited plasma, and thrombin generation was determined in the presence of a fluorogenic substrate.

RESULTS

The maximum level and rate of thrombin generation increased during pregnancy; the highest level and rate occurred in late pregnancy compared with prepregnancy (P < .001). Subsequently, thrombin generation decreased in the postpregnancy samples that included maximum level, rate, and area under the curve (P < .001).

CONCLUSION

Our data provide evidence for an increase in tissue factor-dependent thrombin generation with pregnancy progression, followed by a return to prepregnancy thrombin levels.