Vagal Regulation in Breastfeeding Infants and Their Mothers

Investigating the development of the autonomic nervous system in infancy through pupillometry

We aim to investigate early developmental trajectories of the autonomic nervous system (ANS) as indexed by the pupillary light reflex (PLR) in infants with (i.e. preterm birth, feeding difficulties, or siblings of children with autism spectrum disorder) and without (controls) increased likelihood for atypical ANS development. We used eye-tracking to capture the PLR in 216 infants in a longitudinal follow-up study spanning 5 to 24 months of age, and linear mixed models to investigate effects of age and group on three PLR parameters: baseline pupil diameter, latency to constriction and relative constriction amplitude. An increase with age was found in baseline pupil diameter (F(3,273.21) = 13.15, p < 0.001, [Formula: see text] = 0.13), latency to constriction (F(3,326.41) = 3.84, p = 0.010, [Formula: see text] = 0.03) and relative constriction amplitude(F(3,282.53) = 3.70, p = 0.012, [Formula: see text] = 0.04). Group differences were found for baseline pupil diameter (F(3,235.91) = 9.40, p < 0.001, [Formula: see text] = 0.11), with larger diameter in preterms and siblings than in controls, and for latency to constriction (F(3,237.10) = 3.48, p = 0.017, [Formula: see text] = 0.04), with preterms having a longer latency than controls. The results align with previous evidence, with development over time that could be explained by ANS maturation. To better understand the cause of the group differences, further research in a larger sample is necessary, combining pupillometry with other measures to further validate its value.

Breastfeeding duration and vagal regulation of infants and mothers

BACKGROUND

Vagal regulation within the parasympathetic nervous system supports self-regulation and social engagement. Research has suggested that early feeding practices may influence mother-infant vagal functioning.

AIM

We aimed to examine the association between breastfeeding duration and mother-infant vagal regulation during an interaction. We hypothesized that breastfeeding duration would be positively associated with adaptive vagal regulation in infants and mothers.

METHOD

204 mother-infant dyads (infant mean age 6 months) completed the face-to-face still-face (FFSF) task. During the task, vagal regulation indexed by respiratory sinus arrhythmia (RSA, a component of heart rate variability) was calculated through continuously recorded electrocardiogram signals. Breastfeeding duration and demographic information were reported by mothers. Linear mixed models were adopted to estimate the associations between breastfeeding duration and repeated measures of RSA in infants and mothers throughout the FFSF.

RESULTS

Infants breastfed for a longer duration demonstrated lower RSA throughout the FFSF (B = -0.06, 95 % CI: -0.09 to -0.03), suggesting active physiological mobilization to engage in interaction and regulate distress. Mothers with longer breastfeeding duration displayed higher baseline RSA and higher overall RSA levels (higher vagal control) during the FFSF (B = 0.06, 95 % CI: 0.02 to 0.09), indicating a calmer and regulated state.

CONCLUSION

Longer breastfeeding duration was associated with more adaptive mother-infant vagal regulation during the interaction, indicating a positive dose-response association. This finding reveals breastfeeding practice as a factor contributing to infant effective vagal regulation and further supports WHO recommendation on exclusive breastfeeding for the first 6 months and continuing breastfeeding to 24 months and beyond.

A systematic review and meta-analysis of the association between parenting and child autonomic nervous system activity

Parental socialization may influence the development of children's autonomic nervous system (ANS), a key stress-response system. However, to date no quantitative synthesis of the literature linking parenting and child ANS physiology has been conducted. To address this gap, we conducted a pre-registered meta-analysis. A systematic review of the literature identified 103 studies (n = 13,044 participants) with available effect sizes describing the association between parenting and either parasympathetic nervous system (PNS) or sympathetic nervous system (SNS) activity in children. The overall analysis revealed non-significant associations between parenting and child ANS physiology on average. However, moderation analyses revealed a positive association between more positive parenting and higher resting PNS activity that was stronger when a study was experimental rather than correlational, and when the sample included children with a clinical condition. In conclusion, well-controlled experimental studies show that positive parenting is associated with the development of higher resting PNS activity, an effect that may be stronger among children who are at elevated developmental risk.

Associations of Infant Feeding with Body Composition and Cardiometabolic Health in Young Female University Students

Background:

We assessed the association of infant feeding with body composition and cardiometabolic health at 20 years in a setting where infant feeding is not associated with socioeconomic status.

Materials and methods:

Body size trajectory since birth, current body composition measured using whole-body dual-energy X-ray absorptiometry, and a broad range of cardiometabolic risk factors were compared cross-sectionally among young female university students who were ever breastfed (n = 158, 120 exclusively, and 38 mainly), mixed fed (n = 124), and formula fed (n = 15, 10 mainly, and 5 exclusively)

Results:

Compared with breastfed and mixed fed women, formula fed women had higher serum total and low-density lipoprotein (LDL) cholesterol although fat mass, fat distribution, fasting glucose, and insulin and high-density lipoprotein cholesterol did not differ. In addition, resting heart rates were higher in formula fed women compared with the other two groups of women although systolic and diastolic blood pressure did not differ. Further, formula fed women had higher adiponectin while serum leptin did not differ. There was no difference in birthweight, weight and height in childhood and adolescence, and glucose tolerance. On multivariate logistic regression analysis, formula feeding was associated with resting heart rates (odds ratio [OR]: 1.06, confidence interval [95% CI]; 1.01–1.12, p = 0.01) and adiponectin (OR: 1.3, 95% CI; 1.1–1.5, p < 0.001) independently of serum total and LDL cholesterol.

Conclusions:

Breastfeeding may be associated with favorable lipid profile and autonomic nervous function in young adults through mechanisms unrelated to adiposity, implicating potential long-term benefits of breastfeeding for cardiovascular health. Higher adiponectin in nonbreastfed women warrants further studies.

Exclusive Breastfeeding Moderates the Association Between Prenatal and Postpartum Depression

BACKGROUND

Exclusive breastfeeding has a wide range of benefits for maternal health. However, the benefit of exclusive breastfeeding for maternal mental health needs to be further explored.

RESEARCH AIM

To determine the moderating role of exclusive breastfeeding at 3 months on the association between prenatal and postpartum depression.

METHODS

This study had a prospective, longitudinal, and comparative design with two groups and three assessment waves. The sample comprised 334 participants (70 depressed and 264 non-depressed) recruited at public health services in northern Portugal. Participants completed a measure of depression symptoms between the second and the third trimester of pregnancy and between 3 and 6 months, and a measure of breastfeeding status at 3 months.

RESULTS

Exclusive breastfeeding at 3 months moderated the association between prenatal and postpartum depression. Participants with prenatal depression who were exclusively breastfeeding at 3 months showed fewer symptoms of depression and lower rates of depression between 3 and 6 months postpartum, compared to participants with prenatal depression who were not exclusively breastfeeding. Participants without prenatal depression who were exclusively breastfeeding at 3 months showed similar depression symptoms and similar rates of depression between 3 and 6 months postpartum, compared to participants without prenatal depression who were not exclusively breastfeeding.

CONCLUSION

Exclusive breastfeeding has a potential protective influence on postpartum depression among women with prenatal depression. Public health policies targeting women with prenatal depression should be implemented and include practices to promote and support exclusive breastfeeding in order to enhance women's exclusive breastfeeding and mental health.

Characterizing change in vagal tone during the first three years of life: A systematic review and empirical examination across two longitudinal samples

Functioning of the parasympathetic nervous system (PNS), most often indexed by respiratory sinus arrhythmia (RSA), influences the volitional, cognitively-mediated forms of self-regulation across development. However, despite its clear relevance to children's self-regulation, and its utility as a transdiagnostic biomarker of emotion dysregulation and psychopathology, the ontogeny of vagal tone under conditions of homeostasis across infancy and early childhood is not well understood. The current research is comprised of two complementary studies. The first aims to address this gap by conducting a systematic review of the literature which has assessed resting RSA in the first three years of life. The second study uses data from two diverse, longitudinal datasets (n = 203 and n = 370) to model change in RSA from infancy to toddlerhood. Results from a systematic review of 62 studies meeting inclusion criteria suggest that measures of resting RSA increase over time and demonstrate moderate stability across infancy, toddlerhood, and preschool ages. Results from a series of models fit to longitudinal data in study two suggest that baseline RSA is characterized by stable increases across infancy and early childhood. Moreover, although there was equivocal evidence for individual variability in trajectories of RSA, the findings suggest that the individual differences in resting RSA may become entrenched in early life based on observed significant variance in growth model intercepts. In all, the current study contributes to our understanding of the developmental trajectories of baseline RSA across infancy and early childhood and should support future research examining links between children's parasympathetic regulation and their adjustment in early life.

Feeding During Infancy: Interpersonal Behavior, Physiology, and Obesity Risk

Infancy is a sensitive developmental period that presents both opportunities and challenges for caregivers to feed their infants in ways that support healthy growth and development. The capacity to eat in a way that supports energy (caloric) intake aligned with the body's physiologic need for growth and development appear to diminish in the years following infancy, but the reasons for this and whether this is developmentally typical are unclear. Feeding interactions that undermine infants' ability to regulate their intake in response to hunger and satiety are thought to confer risk for obesity in infancy and beyond. In this integrative review, we consider what we know about the emergence of self-regulation of behavior and emotion from both a behavioral and a physiological perspective. Then, we apply this information to our emerging understanding of how self-regulation of energy intake may be derailed through feeding interactions between caregivers and infants.

Challenges and Coping Strategies of Student Nursing Mothers in University of Ibadan, Oyo State, Nigeria

The rigor of combining motherhood with education poses great challenge to student nursing mothers (SNMs). This study identified the challenges experienced by the SNMs and determined the factors associated with the challenges experienced in University of Ibadan, Ibadan Oyo State, Nigeria. This study utilized a nonprobability sampling technique of snowballing. Responses were elicited from 250 consenting SNMs using the pretested semistructured questionnaire. The SNM challenges were measured on 15-point scale. Challenges scores were classified as moderate (≤9) and severe (≥10). The mean age of the SNMs was 29.5 ± 2.8 years. Majority of the respondents (70.0%) reported facing severe challenges which included economic, childcare, and academic challenges (43.2%, 37.2%, and 24.8%, respectively). χ² test showed significant associations between ages, course of study, and level of study of the SNMs (χ² = 10.520, p = .005; χ² = 14.934, p = .002; and χ² = 9.523, p = .002, respectively) and the overall challenges experienced. Research findings reveal that childhood health problems occurred mostly among SNMs having problems breastfeeding their babies.

Moving from the Margins to the Mainstream: Equity and Justice as Key Considerations for Developmental Science

Worldwide, most children face marginalization and societal inequities to varying degrees. For developmental science to have both scientific and societal value, scientists must account for the impact of societal inequities, regardless of the focus of their research. In this article, we illustrate how equity and justice are relevant for all children. We also argue that equity and justice are essential components for all developmental science and should be the basis for how we evaluate scientific rigor. Ignoring equity and justice issues perpetuates biases within the field and limits our understanding of developmental processes. We offer graduated recommendations for all developmental scientists to consider, starting with minimal standards for inclusion and descriptions of participants, and continuing with guidance for articulating what mechanisms lead to observed differences. We also urge researchers to examine why and how social inequities and contexts shape their focal domain of developmental science.

Parenting Teamwork: The Impact of a Fathering Intervention on Mothers and Infants in Vietnam

A multifaceted, relationally focused intervention involving group and individual pre- and postnatal counseling, print resources, and community resources encouraged 390 fathers of newborn infants in Vietnam to responsively support mothers and work with them as a parenting team. Both partners completed questionnaires prebirth and 1-, 4-, and 9-months postbirth on measures of breastfeeding support, exclusive breastfeeding duration, relationship quality, and infant development. Compared to 412 comparison group couples, intervention couples evidenced greater father support, especially in terms of helping and responsiveness to the mother's needs. This support predicted longer exclusive breastfeeding duration, improved relationship quality, and higher levels of infant development at 9 months. Sensitively working together with mothers as a coordinated team enhanced couple's relationship functioning and improved children's developmental outcomes.

In sync: Physiological correlates of behavioral synchrony in infants and mothers

Infant-mother behavioral synchrony is thought to scaffold the development of self-regulation in the first years of life. During this time, infants' and mothers' physiological regulation may contribute to dyadic synchrony and, in infants, dyadic synchrony may support infants' physiological regulation. Because the sympathetic nervous system (SNS) and parasympathetic nervous system (PNS) serve different regulatory functions, the current study aimed to elucidate relations between infants' and mothers' SNS and PNS functioning and dyadic behavioral synchrony. Skin conductance (SC; SNS index), respiratory sinus arrhythmia (RSA; PNS index), heart period (HP; index of joint SNS and PNS arousal), and behavioral synchrony were assessed in 6-month-old infants (N = 140) and their mothers during a mild social stressor, the Face-to-Face Still-Face paradigm (Tronick, Als, Adamson, Wise, & Brazelton, 1978). Synchrony was related to infants' and mothers' PNS and to mothers' broad autonomic arousal but not to SNS-specific arousal. Higher levels of behavioral synchrony were associated with lower infant RSA but with higher mother HP and RSA at baseline and in each Face-to-Face Still-Face paradigm episode. Therefore, lower RSA infants may have required more synchronous engagement with mothers to support regulation, while higher RSA, less aroused mothers may have been particularly well-attuned to infants' emotions. Findings suggest that each individual's physiological state may contribute to the behavioral functioning of the dyad. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Autonomic nervous system functioning assessed during the Still-Face Paradigm: A meta-analysis and systematic review of methods, approach and findings

Animal and human research suggests that the development of the autonomic nervous system (ANS) is particularly sensitive to early parenting experiences. The Still-Face Paradigm (SFP), one of the most widely used measures to assess infant reactivity and emotional competence, evokes infant self-regulatory responses to parental interaction and disengagement. This systematic review of 33 peer-reviewed studies identifies patterns of parasympathetic (PNS) and sympathetic (SNS) nervous system activity demonstrated by infants under one year of age during the SFP and describes findings within the context of sample demographic characteristics, study methodologies, and analyses conducted. A meta-analysis of a subset of 14 studies with sufficient available respiratory sinus arrhythmia (RSA) data examined whether the SFP reliably elicited PNS withdrawal (RSA decrease) during parental disengagement or PNS recovery (RSA increase) during reunion, and whether results differed by socioeconomic status (SES). Across SES, the meta-analysis confirmed that RSA decreased during the still-face episode and increased during reunion. When studies were stratified by SES, low-SES or high-risk groups also showed RSA decreases during the still face episode but failed to show an increase in RSA during reunion. Few studies have examined SNS activity during the SFP to date, preventing conclusions in that domain. The review also identified multiple qualifications to patterns of SFP ANS findings, including those that differed by ethnicity, infant sex, parental sensitivity, and genetics. Strengths and weaknesses in the extant research that may explain some of the variation in findings across the literature are also discussed, and suggestions for strengthening future research are provided.

Mother-Child Coregulation of Parasympathetic Processes Differs by Child Maltreatment Severity and Subtype

Parasympathetic processes appear to underlie maladaptive parent-child interactions in maltreating families, but it is unknown whether parent-child coregulation of respiratory sinus arrhythmia (RSA) differs by child maltreatment severity and subtype. RSA coregulation in maltreating and nonmaltreating mother-child dyads ( N = 146; age 3-5 years) during two dyadic tasks was analyzed using dynamic time series modeling. Nonmaltreating dyads showed positive RSA concordance but maltreating dyads (when examined as one group) did not. However, when examined separately by subtype, physically abusive dyads showed positive concordance and neglectful dyads no concordance, in dyadic RSA. Patterns were further modified by maltreatment severity, which predicted discordant RSA (one partner's RSA predicting decreases in the other's) in both groups. Specifically, higher physical abuse severity predicted lower resting child RSA, declining mother RSA over time, and mother RSA predicting declines in child RSA over time, suggesting a mother-driven dyadic stress response. Higher neglect severity predicted increasing child RSA over time and child RSA predicting declines in mother RSA over time, suggesting a child-driven maternal stress response. These findings show there are distinct patterns of RSA coregulation in nonmaltreating, physically abusive, and neglectful mother-child dyads, which may inform etiology and intervention with respect to stress regulation in maltreating families.