A recent study published in the journal Scientific Reports observed that maternal heart rate variability (mHRV) three months after birth was associated with infant neurophysiology and maternal mental health.
Postnatal mental health problems are increasingly prevalent among new mothers. This is of particular concern because maternal mental health during the perinatal period may impact the caregiver-infant relationship and child development. However, research in this area relies on self-reported measures of psychological distress, which may be subject to bias and provide limited insight into mechanisms. More accurate objective measures are therefore needed.
The maternal stress physiological system provides insight into how psychological stress affects infant outcomes. HRV is a candidate marker of stress regulation. Research suggests that HRV reflects the balance between parasympathetic and sympathetic activity and can be widely used as an index of physiological stress regulation. mHRV is primarily assessed prenatally, and lower prenatal mHRV has been found to be associated with a higher prevalence of anxiety disorders later in pregnancy.
Study: Maternal heart rate variability three months after birth is associated with maternal mental health and infant neurophysiology. Image credit: THICHA SATAPITANON / Shutterstock
About the Research
In this study, the researchers investigated the association between mHRV and maternal stress, anxiety, and depression, as well as infant stress physiology and neurological function. Mother-infant pairs were recruited from another study conducted between 2018 and 2019. Mothers with multiple births, births before 36 weeks of gestation, or whose children had developmental disabilities were excluded.
Participants visited the lab when their infants were approximately 3 months old and maternal and infant electrocardiograms (ECGs) and infant electroencephalograms (EEGs) were recorded. In addition, mothers completed socio-demographic and mental health questionnaires. Socio-demographic data included infant and maternal age, ethnicity/race, education, and household income.
Income-to-needs ratios were calculated by dividing income by the federal poverty line corresponding to the number of children and adults in the household.Mental health was investigated using the National Trait Anxiety Scale (STAI), Edinburgh Postnatal Depression Scale (EPDS), and Perceived Stress Scale (PSS).Confirmatory factor analysis (CFA) was used to calculate a composite factor score of maternal mental health using the PSS, EPDS, and STAI trait scores.
Resting EEG data were obtained from the infants. Two indices of infant neural activity were assessed: theta-beta ratio and frontal alpha symmetry. Resting ECG data were obtained from the 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 calculated using CFA. Pearson correlations explored the relationship between mHRV variables and (maternal and infant) outcomes. Additionally, multiple regression models explored the relationship between mHRV and infant neurophysiology and maternal mental health.
Survey results
Overall, 104 mother-infant dyads participated, but only 76 dyads participated due to data loss at various stages. The mean age of the mothers was 33 years, and 50% were Hispanic or Latino. The mean age of the infants was 3.4 months, and 66% were male. The research team found a significant negative correlation between mHRV scores and maternal anxiety and depression.
Thus, mothers with lower mHRV had higher rates of anxiety and depression. Furthermore, a trend-level negative correlation was found between mHRV and maternal stress perception. State anxiety was positively correlated with maternal mental health outcomes. Furthermore, mHRV was positively correlated with infant HRV (iHRV) and negatively correlated with theta-beta ratio.
No significant associations with frontal alpha asymmetry were found.Further, exploratory analyses assessed whether coordination of mother-infant dyad HRV moderated 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-s HF HRV epochs.
The positive correlation between iHRV and mHRV was higher in mother-infant dyads with increased physiological synchrony than in dyads with little or no synchrony, and the researchers noted that in dyads with increased physiological synchrony, increased mHRV predicted increased theta-beta ratio via iHRV.
Conclusion
Taken together, these findings reveal associations between mHRV and maternal anxiety and depression, as well as infant neurophysiology. Furthermore, physiological synchronization between the dyad strengthened the association between mHRV and infant neurofunctioning via iHRV. These results support the important role of caregiver well-being in infant development. Future studies with larger sample sizes are needed to confirm these findings.
Journal References:
Brandes-Aitken A, Hume A, Braren S, Werchan D, Zhang M, Brito NH. Maternal heart rate variability in the first 3 months after birth is associated with maternal mental health and infant neurophysiology. Scientific Reports, 2024, DOI: 10.1038/s41598-024-68398-4, https://www.nature.com/articles/s41598-024-68398-4
