Higher maternal weight is related to poorer fetal autonomic function

Impact of maternal emotional state during pregnancy on fetal heart rate variability

Background

The fetal autonomic nervous system (ANS) is believed to be negatively affected by maternal adverse emotional states. In this study, we evaluated how depression, anxiety and stress during pregnancy are related to fetal heart rate variability (HRV) as recorded with magnetocardiography (MCG). We also considered metabolic factors such as maternal adiposity and circulating levels of cortisol during gestation. Furthermore, we followed up these fetuses after birth, recording HRV and saliva levels of cortisol in these infants to establish any effects postpartum.

Methods

We calculated HRV in spontaneous MCG recordings from 32 healthy fetuses between 32 and 38 weeks of gestational age. Maternal emotional state was assessed using standardized questionnaires about anxiety, depression and stress. An overall indicator of maternal well-being was calculated by z-scoring each individual questionnaire and summation. We used a median split to divide the group into high and low z-scores (HZS and LZS), respectively. Standard HRV measures were determined in the time and frequency domain. T-test analyses were performed between LZS and HZS, with the HRV and the metabolic measures as the dependent variables.

Results

We found an impaired HRV in the HZS group both during pregnancy and after birth. No differences were observed between LZS and HZS for metabolic factors. Depression and anxiety symptoms seem to affect HRV differently. No relationship was found between maternal and infant cortisol levels.

Conclusions

On the basis of our results on different HRV parameters, we propose that maternal emotional state might affect the development of the fetal nervous system in utero.

DHA Supplementation During Pregnancy Enhances Maternal Vagally Mediated Cardiac Autonomic Control in Humans

BACKGROUND

DHA is an essential omega-3 (ω-3; n-3) fatty acid that has well-established benefits for the fetus. DHA also has the potential to influence the health of the mother, but this area is understudied.

OBJECTIVES

The objective of this secondary analysis was to determine if DHA was related to maternal heart rate (HR) and heart rate variability (HRV) metrics in a large cohort of pregnant women.

METHODS

In the parent trial (1R01HD086001) eligible participants (≥18 y old, English speaking, carrying a singleton pregnancy, 12-20 wk of gestation) were randomly assigned to consume 200 mg/d or 800 mg/d DHA for the duration of their pregnancy (n = 300). Weight, blood pressure, and magnetocardiograms (MCGs) were collected at 32 wk and 36 wk of gestation (n = 221). Measures of HR and HRV in time-, frequency-, and nonlinear-domains were determined from the isolated maternal MCG. Treatment group and timepoint were examined as predictors in association with HR and HRV metrics using random-intercept mixed-effects ANOVA unadjusted and adjusted models accounting for weight and dietary DHA intake.

RESULTS

Women receiving the higher dose of DHA (800 mg/d) during pregnancy had lower HR, lower sympathetic index, higher vagally mediated HRV indices, and greater HRV complexity when compared with the women who received the lower dose (200 mg/d; all P < 0.05). All the dose relations remained significant even after controlling for the effect of time, maternal weight, and dietary DHA intake.

CONCLUSIONS

DHA supplementation increases vagal tone in pregnant women. Longitudinal studies examining the potential link between DHA, enhanced vagal tone, and reported reduction in early preterm birth are warranted.

Maternal Weight Gain during Pregnancy and the Developing Autonomic Nervous System-Possible Impact of GDM

OBJECTIVE

The intrauterine environment is known to affect the offspring's long-term risk for obesity and diabetes. Previous data show that maternal metabolism and gestational weight gain (GWG) are associated with fetal autonomic nervous system (ANS) function, which can be assessed with heart rate variability (HRV). We investigated whether this association is also present in 2-year-old children and addressed the impact of gestational diabetes (GDM).

RESEARCH DESIGN AND METHODS

We examined the 2-year-old offspring of mothers who had undergone a 5-point, 75 g oral glucose tolerance test during pregnancy. To assess HRV, a 10-minute ECG was recorded, and time domain and frequency domain parameters were analyzed. Body composition was assessed using bioelectrical impedance testing.

RESULTS

We examined 67 children (33 girls, 34 boys), 30 of whom were born to mothers with treated GDM and normoglycemic pregnancies (NGT), respectively. No differences were found between the groups with regard to birth weight, weight at the age of 2 years, and body fat content. We observed that GWG was associated with heart rate and HRV, indicating that children of mothers with low GWG had a lower parasympathetic tone. This association was detected in NGT-exposed-but not in GDM-exposed-children. HR and HRV correlated with body fat and fat-free mass in children from normoglycemic pregnancies only.

CONCLUSION

We found that the impact of maternal GWG on offspring ANS function was missing in the presence of treated GDM. The balance of the ANS was related to offspring body composition in children from NGT pregnancies only. Our results suggest that maternal weight gain during pregnancy has a critical impact on the developing ANS, which might be disturbed in the presence of GDM.

Prenatal docosahexaenoic acid effect on maternal-infant DHA-equilibrium and fetal neurodevelopment: a randomized clinical trial

INTRODUCTION

Maternal-infant equilibrium occurs when cord blood docosahexaenoic acid (DHA) is less than or equal to maternal DHA at delivery. Equilibrium may be an indicator of sufficient DHA for optimal fetal and infant neurodevelopment. The purpose of this study was to test the effect of maternal DHA supplementation on equilibrium status and fetal neurodevelopment.

METHODS

Women enrolled between 12 and 20 weeks gestation and were randomized to 200 or 800 mg DHA/day until delivery. Maternal red blood cell (RBC) phospholipids were measured at enrollment, 32 weeks, delivery, and in cord blood at delivery. Fetal neurodevelopment was measured at 32 and 36 weeks gestation. Intent-to-treat analyses were conducted to test differences in equilibrium status by group. Fetal outcomes were assessed by equilibrium status and group.

RESULTS

Three hundred women enrolled and 262 maternal-infant dyads provided blood samples at delivery. No maternal-infant dyads with maternal RBC-DHA ≤ 6.96% at delivery achieved equilibrium. The incidence of equilibrium was significantly higher in the 800 mg group. There was no effect of maternal group or equilibrium status on fetal neurodevelopment.

CONCLUSION

The significance of maternal-infant DHA equilibrium remains unknown. Ongoing research will test the effect of treatment group, equilibrium, and nutrient status on infant behavior and brain function.

IMPACT

Pregnant women who received a higher dose of docosahexaenoic acid (DHA) were more likely to achieve maternal-infant DHA equilibrium at delivery. Equilibrium status had no effect on fetal neurodevelopment in this sample. While DHA is crucial for early life neurodevelopment, the significance of achieving maternal-infant equilibrium above the lower threshold is uncertain. There is a lower threshold of maternal DHA status where maternal-infant DHA equilibrium never occurs. The lack of equilibrium associated with low maternal DHA status may indicate insufficient maternal status for optimal placental transfer.

A Review on the Vagus Nerve and Autonomic Nervous System During Fetal Development: Searching for Critical Windows

The autonomic nervous system (ANS) is one of the main biological systems that regulates the body's physiology. Autonomic nervous system regulatory capacity begins before birth as the sympathetic and parasympathetic activity contributes significantly to the fetus' development. In particular, several studies have shown how vagus nerve is involved in many vital processes during fetal, perinatal, and postnatal life: from the regulation of inflammation through the anti-inflammatory cholinergic pathway, which may affect the functioning of each organ, to the production of hormones involved in bioenergetic metabolism. In addition, the vagus nerve has been recognized as the primary afferent pathway capable of transmitting information to the brain from every organ of the body. Therefore, this hypothesis paper aims to review the development of ANS during fetal and perinatal life, focusing particularly on the vagus nerve, to identify possible "critical windows" that could impact its maturation. These "critical windows" could help clinicians know when to monitor fetuses to effectively assess the developmental status of both ANS and specifically the vagus nerve. In addition, this paper will focus on which factors-i.e., fetal characteristics and behaviors, maternal lifestyle and pathologies, placental health and dysfunction, labor, incubator conditions, and drug exposure-may have an impact on the development of the vagus during the above-mentioned "critical window" and how. This analysis could help clinicians and stakeholders define precise guidelines for improving the management of fetuses and newborns, particularly to reduce the potential adverse environmental impacts on ANS development that may lead to persistent long-term consequences. Since the development of ANS and the vagus influence have been shown to be reflected in cardiac variability, this paper will rely in particular on studies using fetal heart rate variability (fHRV) to monitor the continued growth and health of both animal and human fetuses. In fact, fHRV is a non-invasive marker whose changes have been associated with ANS development, vagal modulation, systemic and neurological inflammatory reactions, and even fetal distress during labor.