Is fetal cardiac function gender dependent?

Prenatal Diagnosis of Congenital Heart Diseases and Associations with Serum Biomarkers of Aneuploidy: A Multicenter Prospective Cohort Study

PURPOSE

We assessed prenatal detection rates of congenital heart disease (CHD) and associations between maternal serum biomarkers and non-chromosomal CHD in singleton pregnancies.

MATERIALS AND METHODS

This study was conducted as a secondary analysis of data obtained during a multicenter prospective cohort study that investigated the cost-effectiveness of prenatal testing for fetal aneuploidy. We analyzed the prenatal detection rate and accuracy for CHD screening via ultrasound during the second trimester, as well as associations between serum biomarkers and CHDs, in singleton newborns without chromosomal abnormalities.

RESULTS

Among 6715 women, 142 (2.1%) newborns were born with CHDs, of which 67 (1.0%) newborns had major CHDs. The prenatal detection rate for all CHDs and major CHDs were 34.5% and 58.2%, respectively. After excluding isolated ventricular septal defects, the detection rate for critical CHDs was 85.9%. Women with low pregnancy-associated plasma protein A (PAPP-A) (<0.4 multiples of the median, MOM) face increased risks of non-chromosomal CHDs [adjusted odds ratio (aOR) 2.76; 95% confidence interval (CI) 1.36-5.13] and major CHDs (aOR 7.30; 95% CI 3.18-15.59), compared to those without CHDs. A higher inhibin A level (≥2.5 MOM; aOR 4.84; 95% CI 1.42-12.46) was associated with non-chromosomal major CHDs.

CONCLUSION

Ultrasonography performed during the second trimester by obstetricians detected over 85% of critical CHDs. Low maternal serum PAPP-A or high inhibin-A was associated with non-chromosomal CHDs. These results may contribute to an improvement in prenatal diagnosis of CHDs.

Asphyxiated Female and Male Newborn Piglets Have Similar Outcomes With Different Cardiopulmonary Resuscitation Interventions

Background: Male newborns have a greater risk of poor cardiovascular and respiratory outcomes compared to females. The mechanisms associated with the "male disadvantage" remains unclear. We have previously shown no difference between male and female newborn piglets during hypoxia, asphyxia, resuscitation, and post-resuscitation recovery. However, it is unknown if there are differences in resuscitation outcomes between males and females during different cardiopulmonary resuscitation techniques. Intervention and Measurements: Secondary analysis of 184 term newborn mixed breed duroc piglets (1-3 days of age, weighing 2.0 (0.2) kg) from seven different studies, which were exposed to 30-50 min of normocapnic hypoxia followed by asphyxia until asystole. This was followed by cardiopulmonary resuscitation. For the analysis, piglets were divided into male and female groups, as well as resuscitation technique groups (sustained inflation, 3:1 compression-to-ventilation ratio, or asynchronous ventilations during chest compressions). Cardiac function, carotid blood flow, and cerebral oxygenation were continuously recorded throughout the experiment. Main results: Regardless of resuscitation technique, there was no significant difference between males and females in the number achieving return of spontaneous circulation (ROSC) [95/123 (77%) vs. 48/61 (79%)], the time to achieve ROSC [112 (80-185) s vs. 110 (77-186) s], and the 4-h survival rate [81/95 (85%) vs. 40/48 (83%)]. Levels of the injury markers interleukin (IL)-1ß, IL-6, IL-8, and tumor necrosis factor-α in frontoparietal cortex tissue homogenates were similar between males and females. Conclusions: Regardless of resuscitation technique, there was no significant effect of sex on resuscitation outcome, survival, and hemodynamic recovery in asphyxiated newborn piglets.

Mechanisms of Sex Disparities in Cardiovascular Function and Remodeling

Epidemiological studies demonstrate disparities between men and women in cardiovascular disease prevalence, clinical symptoms, treatments, and outcomes. Enrollment of women in clinical trials is lower than men, and experimental studies investigating molecular mechanisms and efficacy of certain therapeutics in cardiovascular disease have been primarily conducted in male animals. These practices bias data interpretation and limit the implication of research findings in female clinical populations. This review will focus on the biological origins of sex differences in cardiovascular physiology, health, and disease, with an emphasis on the sex hormones, estrogen and testosterone. First, we will briefly discuss epidemiological evidence of sex disparities in cardiovascular disease prevalence and clinical manifestation. Second, we will describe studies suggesting sexual dimorphism in normal cardiovascular function from fetal life to older age. Third, we will summarize and critically discuss the current literature regarding the molecular mechanisms underlying the effects of estrogens and androgens on cardiac and vascular physiology and the contribution of these hormones to sex differences in cardiovascular disease. Fourth, we will present cardiovascular disease risk factors that are positively associated with the female sex, and thus, contributing to increased cardiovascular risk in women. We conclude that inclusion of both men and women in the investigation of the role of estrogens and androgens in cardiovascular physiology will advance our understanding of the mechanisms underlying sex differences in cardiovascular disease. In addition, investigating the role of sex-specific factors in the development of cardiovascular disease will reduce sex and gender disparities in the treatment and diagnosis of cardiovascular disease. © 2019 American Physiological Society. Compr Physiol 9:375-411, 2019.

Sex differences in fetal heart rate and variability assessed by antenatal computerized cardiotocography

INTRODUCTION

The aim of the current study is to explore the effect of fetal sex on the fetal heart rate and variability.

MATERIAL AND METHODS

This is a retrospective cross-sectional study. We analyzed fetal heart rate (FHR) traces of pregnant women that were recorded antenatally using a commercially available computerized cardiotocograph (cCTG; Oxford system). Fetal sex was ascertained after birth. Baseline FHR and short-term heart rate variation (STV) were compared between male and female fetuses. Expected mean values for baseline FHR and STV were computed and multiples of the mean (MOMean) of males and females were compared.

RESULTS

Information on 9259 cases is reported in this study. Baseline FHR of female fetuses was significantly higher (P < 0.001) and STV lower (P < 0.001) than that of male fetuses. This difference remained even after the effects of gestational age and diurnal variation were eliminated by computation of MOMean, but the absolute differences in the baseline FHR (0.9 beats/min [bpm]) and STV (0.246 ms) between male and female fetuses were small. A significant negative correlation was found between baseline FHR and STV (r = -0.518, P < 0.001). Similarly, a significant negative correlation was found between the MoMean of baseline FHR and MoMean STV (r = -0.481, P < 0.001).

CONCLUSIONS

Using the Oxford cCTG, male fetuses show a significantly lower baseline FHR and greater variability as compared with female fetuses. However, the absolute differences are small and may not be of major clinical significance.

Sex differences in umbilical artery Doppler indices: a longitudinal study

Background

Sexual dimorphism in placental size and function has been described. Whether this influences the clinically important umbilical artery (UA) waveform remains controversial, although a few cross-sectional studies have shown sex differences in UA pulsatility index (PI). Therefore, we tested whether fetal sex influences the UA Doppler indices during the entire second half of pregnancy and aimed to establish sex-specific reference ranges for UA Doppler indices if needed.

Methods

Our main objective was to investigate gestational age-associated changes in UA Doppler indices during the second half of pregnancy and compare the values between male and female fetuses. This was a prospective longitudinal study in women with singleton low-risk pregnancies during 19–40 weeks of gestation. UA Doppler indices were serially obtained at a 4-weekly interval from a free loop of the umbilical cord using color-directed pulsed-wave Doppler ultrasonography. Sex-specific reference intervals were calculated for the fetal heart rate (HR), UA PI, resistance index (RI), and systolic/diastolic ratio (S/D) using multilevel modeling.

Results

Complete data from 294 pregnancies (a total of 1261 observations from 152 male and 142 female fetuses) were available for statistical analysis, and sex-specific reference ranges for the UA Doppler indices and fetal HR were established for the last half of pregnancy. UA Doppler indices were significantly associated with gestational age (P < 0.0001) and fetal HR (P < 0.0001). Female fetuses had 2–8% higher values for UA Doppler indices than male fetuses during gestational weeks 20⁺⁰–36⁺⁶ (P < 0.05), but not later. Female fetuses had higher HR from gestational week 26⁺⁰ until term (P < 0.05).

Conclusions

We have determined gestational age-dependent sex differences in UA Doppler indices and fetal HR during the second half of pregnancy, and correspondingly established new sex-specific reference ranges intended for refining diagnostics and monitoring individual pregnancies.

Assessment of Fetal Development Using Cardiac Valve Intervals

An automated method to assess the fetal physiological development is introduced which uses the component intervals between fetal cardiac valve timings and the Q-wave of fetal electrocardiogram (fECG). These intervals were estimated automatically from one-dimensional Doppler Ultrasound and noninvasive fECG. We hypothesize that the fetal growth can be estimated by the cardiac valve intervals. This hypothesis was evaluated by modeling the fetal development using the cardiac intervals and validating against the gold standard gestational age identified by Crown-Rump Length (CRL). Among the intervals, electromechanical delay time, isovolumic contraction time, ventricular filling time and their interactions were selected in a stepwise regression process that used gestational age as the target in a cohort of 57 fetuses. Compared with the gold standard age, the newly proposed regression model resulted in a mean absolute error of 3.8 weeks for all recordings and 2.7 weeks after excluding the low quality recordings. Since Fetal Heart Rate Variability (FHRV) has been proposed in the literature for assessing the fetal development, we compared the performance of gestational age estimation by our new valve-interval based method, vs. FHRV, while assuming the CRL as the gold standard. The valve interval-based method outperformed both the model based on FHRV. Results of evaluation for 30 abnormal cases showed that the new method is less affected by arrhythmias such as tachycardia and bradycardia compared to FHRV, however certain types of heart anomalies cause large errors (more than 10 weeks) with respect to the CRL-based gold standard age. Therefore, discrepancies between the regression based estimation and CRL age estimation could indicate the abnormalities. The cardiac valve intervals have been known to reflect the autonomic function. Therefore the new method potentially provides a novel approach for assessing the development of fetal autonomic nervous system, which may be growth curve independent.

Exploring sexual dimorphism in placental circulation at 22-24 weeks of gestation: A cross-sectional observational study

INTRODUCTION

Placental blood flow is closely associated with fetal growth and wellbeing. Recent studies suggest that there are differences in blood flow between male and female fetuses. We hypothesized that sexual dimorphism exists in fetal and placental blood flow at 22-24 weeks of gestation.

METHODS

This was a prospective cross-sectional study of 520 healthy pregnant women. Blood flow velocities of the middle cerebral artery (MCA), umbilical artery (UA), umbilical vein (UV) and the uterine arteries (UtA) were measured using Doppler ultrasonography. UV and UtA diameters were measured using two-dimensional ultrasonography and power Doppler angiography. Volume blood flows (Q) of the UV and UtA were calculated. Maternal haemodynamics was assessed with impedance cardiography. UtA resistance (R_uta) was computed as MAP/Q_uta.

RESULTS

UA PI was significantly (p = 0.008) higher in female fetuses (1.19 ± 0.15) compared with male fetuses (1.15 ± 0.14). MCA PI, cerebro-placental ratio (MCA PI/UA PI), Q_uv, UtA PI, Q_uta and R_uta were not significantly different between groups. At delivery, the mean birth weight and placental weight of female infants (3504 g and 610 g) were significantly (p = 0.0005 and p = 0.039) lower than that of the male infants (3642 g and 634 g).

DISCUSSION

We have demonstrated sexual dimorphism in UA PI, a surrogate for placental vascular resistance, at 22-24 weeks of gestation. Therefore, it would be useful to know when this difference emerges and whether it translates into blood flow differences that may impact upon the fetal growth trajectory.

Sex-related differences in the development of fetal heart rate dynamics

BACKGROUND

Despite previous efforts to explain the general advantages of female fetuses over males regarding health, sex-related differences in the dynamics or complexity of fetal heart rate (FHR) variability and FHR maturation patterns have not yet been identified.

AIM

To make linear and nonlinear comparisons of antepartum FHR indices, dynamics, complexity, and reactivity to the non-stress test (NST) and vibroacoustic-stimulation test (VAST) in male and female fetuses.

STUDY DESIGN

A total of 3835 singleton term deliveries without maternal and fetal complications were divided into female (n=1849) and male (n=1986) groups, and subjected to comparison and analyses.

SUBJECTS

Linear FHR indices, approximate entropy (ApEn), sample entropy (SampEn), short-term/long-term exponents (α1/α2), correlation dimension (CD), NST and VAST criteria, and modified nonlinear reactive criteria (MNRC) were used to evaluate outcomes.

RESULTS

ApEn was consistently higher in female fetuses than in male ones. ApEn in female fetuses was maximal at 29-30 gestational weeks, while the increase in ApEn was delayed in male fetuses but more rapid, reaching its peak at 31-32 gestational weeks. In both sexes, CD increased up to term, and α2 rapidly decreased up to 31-32weeks in an analogous manner. The two sexes differed significantly in response to VAST at <31 gestational weeks and there was a structural difference in reactive patterns under MNRC.

CONCLUSIONS

Female fetuses exhibit greater heart rate dynamics in early gestational periods, suggesting that their cardiovascular system matures earlier than that of males. Male fetuses undergo a compensatory period of rapid change to catch up with females at term.

Reference values for fetal tissue velocity imaging and a new approach to evaluate fetal myocardial function

OBJECTIVES

Myocardial function can be evaluated using color-coded tissue velocity imaging (TVI) to analyze the longitudinal myocardial velocity profile, and by expressing the motion of the atrioventricular plane during a cardiac cycle as coordinated events in the cardiac state diagram (CSD). The objective of this study was to establish gestational age specific reference values for fetal TVI measurements and to introduce the CSD as a potential aid in fetal myocardial evaluation.

METHODS

TVI recordings from 125 healthy fetuses, at 18 to 42 weeks of gestation, were performed with the transducer perpendicular to the apex to provide a four-chamber view. The myocardial velocity data was extracted from the basal segment of septum as well as the left and right ventricular free wall for subsequent offline analysis.

RESULTS

During a cardiac cycle the longitudinal peak velocities of septum increased with gestational age, as did the peak velocities of the left and right ventricular free wall, except for the peak velocity of post ejection. The duration of rapid filling and atrial contraction increased during pregnancy while the duration of post ejection decreased. The duration of pre ejection and ventricular ejection did not change significantly with gestational age.

CONCLUSION

Evaluating fetal systolic and diastolic performance using TVI together with CSD could contribute to increase the knowledge and understanding of fetal myocardial function and dysfunction. The pre and post ejection phases are the variables most likely to indicate fetuses with abnormal myocardial function.