Maternal heart rate variability tied to postpartum mental health and infant brain development, study reveals

By Tarun Sai LomteReviewed by Susha Cheriyedath, M.Sc.Aug 14 2024

A recent study published in the journal Scientific Reports observed that maternal heart rate variability (mHRV) at three months postpartum is associated with infant neurophysiology and maternal mental health.

Postpartum mental health issues have increasingly become prevalent among new mothers. This is particularly concerning as the mental health of mothers in the perinatal period can shape the caregiver-infant relationship and child development. Nonetheless, research in this field has relied on self-reported measures of psychological distress, which can lead to bias and offer limited mechanistic insights. Therefore, objective measures that are more accurate are warranted.

Maternal stress physiology system can provide insights into how psychological distress influences infant outcomes. HRV is a candidate marker for stress regulation. Studies suggest that HRV reflects the balance between parasympathetic and sympathetic activities and could broadly be used to index physiological stress regulation. mHRV is predominantly assessed in the prenatal period, and lower prenatal mHRV has been associated with a higher prevalence of anxiety disorders in late pregnancy.

Study: Maternal heart rate variability at 3-months postpartum is associated with maternal mental health and infant neurophysiology. Image Credit: THICHA SATAPITANON / Shutterstock

About the study

In the present study, researchers examined associations between mHRV and maternal stress, anxiety and depression, and infant stress physiology and neural function. Mother-infant dyads were recruited from a different study conducted in 2018-19. Mothers were excluded if they had multiple births, gave birth before 36 gestational weeks, or their child had developmental disorder(s).

Participants visited the laboratory when the infant was about three months old, when electrocardiogram (ECG) of mothers and infants and electroencephalogram (EEG) of infants were recorded. Besides, mothers completed questionnaires on sociodemographics and mental health. Sociodemographic data included infant and maternal age, ethnicity/race, education, and household income.

An income-to-needs ratio was computed by dividing the income by the federal poverty line corresponding to the household number of children and adults. Mental health was surveyed using the State-Trait Anxiety Inventory (STAI), Edinburgh postnatal depression scale (EPDS), and Perceived Stress Scale (PSS). Confirmatory factor analysis (CFA) was used to compute a composite factor score for maternal mental health using PSS, EPDS, and STAI-trait scores.

Resting EEG data were acquired from infants. Two measures of infant neural activity were evaluated: theta-beta ratio and frontal alpha symmetry. Resting ECG data were acquired from infants and mothers. Three HRV indices were calculated: detrended fluctuation analysis (DFA) alpha 1, high-frequency (HF) band power, and low-frequency (LF)-to-HF ratio.

A single latent factor score for HRV was computed using CFA. Pearson's correlations explored the relations between mHRV variables and (maternal and infant) outcomes. Further, multiple regression models investigated the relationship of mHRV with infant neurophysiology and maternal mental health.

Findings

Overall, 104 mother-infant dyads were recruited; however, only 76 dyads were included due to data loss at different stages. Mothers were aged 33, on average, and 50% were Hispanic or Latino. On average, infants were 3.4 months old, and 66% were males. The team found a significant negative association between mHRV scores and maternal anxiety and depression.

That is, mothers with lower mHRV had higher rates of anxiety and depression. Besides, a trend-level negative association was found between mHRV and maternal perceived stress. State anxiety was positively associated with maternal mental health outcomes. In addition, mHRV was positively associated with infant HRV (iHRV) and negatively with theta-beta ratios.

No significant associations were observed with frontal alpha asymmetry. In addition, an exploratory analysis evaluated whether the coordination of mother-infant dyadic HRV moderates the relationship between mHRV and infant neurophysiology. Physiological synchrony between iHRV and mHRV was calculated by estimating zero-lag cross-correlations within each dyad between 30-second HF HRV epochs.

The positive association between iHRV and mHRV was higher among mother-infant dyads with increased physiological synchrony than those with no or little synchrony. Moreover, the researchers noted that, for dyads with higher physiological synchrony, increased mHRV predicted elevated theta-beta ratios via iHRV.

Conclusions

Taken together, the findings revealed an association of mHRV with maternal anxiety and depression and infant neurophysiology. Besides, dyadic physiological synchrony amplified the association between mHRV and infant neural function via iHRV. These results reinforce the crucial role of the caregiver's well-being in infant development. Future studies with larger sample sizes are needed to corroborate these findings.