Breastfeeding, brain activation to own infant cry, and maternal sensitivity

A common neural response to perceiving but not implicitly regulating infant and adult affect in postpartum mothers

The transition to parenthood requires parents develop caregiving behaviors, such as the ability to identify their infant's emotions and regulate their own emotional response. Research has identified patterns of neural activation in parenting contexts that are interpreted as socioemotional processing. However, no prior research has directly tested whether mothers' neural responses to their infant's affect are the same as those involved in emotion perception/experience and regulation in other contexts. We employed conjunction analyses to clarify which components of mothers' neural response to viewing their infant's affect are shared with passively viewing and labeling adult affective faces (emotion perception/experience and implicit emotion regulation, respectively) in 24 mothers three months postpartum. Our results support a common neural response to viewing infant and adult affect in regions associated with emotion perception/experience (bilateral hippocampi, amygdalae, thalami, orbitofrontal cortex, and ventrolateral prefrontal cortex), but no areas of common response to viewing negative infant affect and implicitly regulating negative adult affect outside of the occipital lobe and cerebellum. This study provides corroborating evidence for shared neural patterns being involved in perceiving/experiencing infant and adult affect but not implicit regulation of infant and adult negative affect.

Exclusive breastfeeding mitigates the association between prenatal maternal pandemic-related stress and children sleep problems at 24 months of age

Infant sleep quality is increasingly regarded as an important factor for children long-term functioning and adaptation. The early roots of sleep disturbances are still poorly understood and likely involve a complex interplay between prenatal and postnatal factors. This study investigated whether exclusive breastfeeding during the first 6 months moderated the association between maternal prenatal pandemic-related stress (PRS) and sleep problems in 24-months children born during the COVID-19 pandemic. We also explored the potential contribution of maternal postnatal anxiety in these relations. Seventy-eight infants (50% males) and their mothers provided complete data from birth to 24 months. Between 12 and 48 h from birth, maternal PRS during pregnancy was retrospectively reported as well as maternal anxiety and exclusive breastfeeding. Maternal anxiety and exclusive breastfeeding were also reported at 3 and 6 months after childbirth. Children sleep disturbances were reported at 24 months. Bayesian analyses revealed that maternal PRS was positively associated with sleep problems in children who were not exclusively breastfed from birth to 6 months. Findings add to the growing literature on the lasting impact of early pre- and postnatal experiences on child well-being and development.

Maternal cortisol concentration is associated with reduced brain activation to infant cry and more intrusive parenting behavior

Previous research indicates that maternal cortisol function and maternal brain response to infant are each in turn related to variations in parenting behavior. However, little is known about how maternal cortisol and maternal brain function are associated, thus studying these two mechanisms together may improve our understanding of how maternal cortisol assessed during interactions with own infant is associated with brain response to infant cry. First-time mothers (N = 59) of infants aged 3-4 months old were recruited to participate. Mothers' cortisol concentration was measured during a naturalistic interaction with their infant and their behavior was coded for two parenting behaviors-- maternal sensitivity and non-intrusiveness. In an fMRI session, mothers listened to their own infant and a control infant crying. Higher cortisol concentration was associated with more intrusive behavior. We found greater cortisol concentration was further associated with decreased activation in the brain to infant cry in the right precentral gyrus, the left culmen extending into the left inferior temporal gyrus and fusiform, two clusters in the superior temporal gyrus, and in the medial frontal gyrus. We also found that lower activation in these regions was associated with more intrusive maternal behavior. These data demonstrate the associations between maternal cortisol concentration and reduced brain activation to infant cry in both motor planning and auditory processing regions in predicting intrusive parenting behavior.

Bridging Neurobiological Insights and Clinical Biomarkers in Postpartum Depression: A Narrative Review

Postpartum depression (PPD) affects 174 million women worldwide and is characterized by profound sadness, anxiety, irritability, and debilitating fatigue, which disrupt maternal caregiving and the mother-infant relationship. Limited pharmacological interventions are currently available. Our understanding of the neurobiological pathophysiology of PPD remains incomplete, potentially hindering the development of novel treatment strategies. Recent hypotheses suggest that PPD is driven by a complex interplay of hormonal changes, neurotransmitter imbalances, inflammation, genetic factors, psychosocial stressors, and hypothalamic-pituitary-adrenal (HPA) axis dysregulation. This narrative review examines recent clinical studies on PPD within the past 15 years, emphasizing advancements in neuroimaging findings and blood biomarker detection. Additionally, we summarize recent laboratory work using animal models to mimic PPD, focusing on hormone withdrawal, HPA axis dysfunction, and perinatal stress theories. We also revisit neurobiological results from several brain regions associated with negative emotions, such as the amygdala, prefrontal cortex, hippocampus, and striatum. These insights aim to improve our understanding of PPD's neurobiological mechanisms, guiding future research for better early detection, prevention, and personalized treatment strategies for women affected by PPD and their families.

Associations Between Breastfeeding, Maternal Emotional Availability, and Infant-Mother Attachment: The Role of Coparenting

BACKGROUND

Breastfeeding is a parenting practice that combines close intimate contact with the opportunity to be sensitive and responsive to the infant, and may have direct and indirect relations with infant attachment. However, researchers have produced inconsistent findings, suggesting there may be other mechanisms involved. Coparenting may play a significant role, as it has been consistently associated with mother-infant relationships.

RESEARCH AIMS

The aims of this study were to examine: (1) whether breastfeeding would be directly associated with infant-mother attachment; (2) whether this association was also indirect, through mothers' quality of caregiving; and (3) whether partners' coparenting support moderates breastfeeding's indirect association with attachment.

METHODS

This was a prospective, longitudinal study that drew data from a larger NIH-funded study on sleep and family relationships (R01HD052809). Mothers reported on their feeding practices and coparenting relationships. Independent observations were used to assess mothers' emotional availability toward infants. A separate team of observers assessed infant-mother attachment.

RESULTS

Exclusive breastfeeding during the first 6 months, and longer duration of any breastfeeding across the 1st year, were directly associated with more secure infant-mother attachment. These associations were also indirect, through maternal emotional availability. Coparenting was a significant moderator, such that the influence of longer breastfeeding duration on improved emotional availability, and, in turn, on more secure attachment, was significant only for mothers who perceived coparenting quality to be low.

CONCLUSION

Findings highlighted the importance of breastfeeding on both the quality of mothering and infant attachment, but also emphasized that coparenting support may be particularly important for mothers who are unable to breastfeed.

Pregnancy renders anatomical changes in hypothalamic substructures of the human brain that relate to aspects of maternal behavior

Animal studies have shown that pregnancy is associated with neural adaptations that promote maternal care. The hypothalamus represents a central structure of the mammalian maternal brain and hormonal priming of specific hypothalamic nuclei plays a key role in the induction and expression of maternal behavior. In humans, we have previously demonstrated that becoming a mother involves changes in grey matter anatomy, primarily in association areas of the cerebral cortex. In the current study, we investigated whether pregnancy renders anatomical changes in the hypothalamus. Using an advanced delineation technique, five hypothalamic substructures were defined in longitudinal MRI scans of 107 women extracted from two prospective pre-conception cohort studies, including 50 women who were scanned before and after pregnancy and 57 nulliparous control women scanned at a similar time interval. We showed that becoming a mother is associated with volume reductions in the anterior-superior, superior tuberal and posterior hypothalamus. In addition, these structural changes related to hormonal levels during pregnancy and specific aspects of self-reported maternal behavior in late pregnancy, including maternal-fetal attachment and nesting behavior. These findings show that pregnancy leads to changes in hypothalamic anatomy and suggest that these contribute to the development of maternal behavior in humans, supporting the conservation of key aspects of maternal brain circuitry and their role in maternal behavior across species.

Neural processing of cry sounds in the transition to fatherhood: Effects of a prenatal intervention program and associations with paternal caregiving

This study examined whether neural processing of infant cry sounds changes across the transition to fatherhood (i.e., from the prenatal to postnatal period), and examined whether an interaction-based prenatal intervention modulated these changes. Furthermore, we explored whether postnatal activation in brain regions showing transition or intervention effects was associated with sensitive care and involvement. In a randomized controlled trial, 73 first-time expectant fathers were enrolled, of whom 59 had at least 1 available fMRI scan. Intervention and transition effects on cry processing were analyzed in the amygdala and superior frontal gyrus (SFG) using linear mixed effect models with all available data and with intent-to-treat analyses. Further, exploratory whole-brain analyses were performed. ROI analyses suggest that the transition to fatherhood is characterized by decreasing activation in response to cry vs control sounds in the amygdala but not SFG. Exploratory whole-brain analyses also show a decrease in activation over the transition to fatherhood in the sensorimotor cortex, superior lateral occipital cortex, hippocampus, and regions of the default mode network. In the putamen and insula, larger decreases were found in fathers with more adverse childhood caregiving experiences. In regions showing transitional changes, higher postnatal activation was associated with more concurrent parenting sensitivity. No effects of the intervention were found. The decrease in activation from the pre- to postnatal period may reflect fathers' habituation to cry sounds over repeated exposures. The positive association between postnatal neural activation and paternal sensitive care suggest that continued sensitivity to cry sounds may be conducive to parenting quality.

Humanity's evolved nest and its relation to cardiac vagal regulation in the first years of life

BACKGROUND

The Evolved Developmental Niche (EDN) is a millions-year-old developmental system that matches the maturational schedule of the offspring, optimizing health. Every animal has a developmental niche.

AIMS

Humanity has fallen away from providing its EDN. Does it matter?

STUDY DESIGN

Several components of humanity's EDN were reviewed (breastfeeding, positive touch, allomothers, responsive care, free play) in relation to cardiac vagal nerve regulation, a signal of healthy development. Focal subjects were young children.

OUTCOME MEASURES

A review of research on the selected EDN components in relation to vagal nerve function was performed. Data were available for all but the allomother component, which is typically not measured by western researchers, although allomothers provide EDN components alongside parents.

RESULTS

Apart from the lack of research on allomother effects, all these EDN components have been shown to influence cardiac vagal regulation in young children.

CONCLUSIONS

Converging evidence suggests that providing the EDN in early life may not only support aspects of a child's primal health system, but bolster capacities for social health and wellness, the cornerstone of a positive life trajectory.

Factors related to a disturbance in the mother-child bond and attachment

INTRODUCTION

Establishing an adequate bond and attachment between a mother and child is essential for preventing pathologies and developing this relationship in the future.

PURPOSE

To identify the factors related to a disturbance of the mother-child bond or attachment.

METHODS

A cross-sectional descriptive study was carried out with women with a biological child between 6 weeks and 18 months of age. The Mother-Child Bond-Attachment Questionnaire (VAMF, for its name in Spanish) was administered to measure the bond and postnatal attachment together with a questionnaire containing sociodemographic, psychosocial, and health variables referring to the mother and the newborn.

RESULTS

1114 women participated. The multivariate analysis showed that skin-to-skin contact (aOR = 0.58; 95% CI: 0.37, 0.90) and breastfeeding (aOR = 0.55; 95% IC: 0.35, 0.86) reduce the probability of presenting a bond disturbance. Anxiety during pregnancy, childbirth, and the puerperium (aOR = 3.95; 95% CI: 2.57, 6.05) and postpartum complications (aOR = 1.60; 95% CI: 1.03, 2.48) increase the chance of having a bond disturbance. Skin-to-skin contact (aOR = 0.61; 95% CI: 0.38, 1.00), breastfeeding (aOR = 0.47; 95% CI: 0.27, 0.80,) and an older age of the infant (months) (aOR = 0.77: 95% CI: 0.72, 0.82) reduces the probability of presenting an attachment disturbance.

CONCLUSIONS

Skin-to-skin contact and breastfeeding are associated with a lower probability of impaired bonding and attachment. Anxiety states during pregnancy, childbirth, and the puerperium, and complications after childbirth increase the probability of developing a bond disorder. The older the age of the infant, the lower the frequency of having an impaired attachment.

IMPLICATIONS TO PRACTICE

Identifying the factors associated with the establishment of the mother-child bond and attachment is essential for the development of prevention strategies and early identification of cases that may present alterations and avoid their consequences on the health of the mother and child.

Unfolding of maternal-infant bonding amidst the COVID-19 pandemic: Social support as a risk and protective factor

BACKGROUND

Social, familial, and physiological stressors may put maternal-infant bonding at risk. Therefore, it is plausible that the stressful conditions brought on by COVID-19 could influence maternal-infant bonding. This study aimed to elucidate the contribution of COVID-19-related experience to variance in maternal-infant bonding, beyond that of established risk factors and as moderated by social support.

METHODS

This longitudinal, multicenter study examined the relationship of demographic and obstetric variables, social support, postpartum depression, as well as COVID-19-related fear, exposure, and subjective difficulty with mother-infant bonding six months following birth. Participants (N = 246) were women who delivered during the pandemics' strict lockdown period and were recruited 10 weeks after a liveborn delivery and followed up six months later.

RESULTS

Relationship between fear of COVID-19 and maternal-infant bonding was moderated by social support: Amongst mothers with high levels of social support, fear of COVID-19 negatively predicted bonding.

DISCUSSION

Results indicate that social support, while overall a protective factor for mother-infant bonding, may lose its buffering effect when fear of COVID-19 is high. This relationship was maintained even when early bonding experiences such as forced separation and the risk incurred by postpartum depression were accounted for. Implications for providers are discussed.

Association of Breastfeeding Duration with Neurodevelopmental Outcomes in an Enriched Familial Likelihood Cohort for Autism Spectrum Disorder

This study aimed to compare the breastfeeding (BF) duration of the younger siblings of children with ASD in an enriched-likelihood cohort for autism spectrum disorder (ASD), and to determine whether longer BF duration was associated with differences in neurodevelopmental outcomes in this cohort. Information on BF practices was collected via surveys in the MARBLES (Markers of Autism Risk in Babies-Learning Early Signs) study. Developmental evaluations, including the Mullen Scales of Early Learning and the Autism Diagnostic Observation Schedule, were conducted by expert clinicians. Participants' neurodevelopmental outcome was classified by an algorithm into three groups: typical development, ASD, and non-typical development. The median duration of BF was 10.70 months (interquartile range of 12.07 months). There were no significant differences in the distribution of duration of BF among the three neurodevelopmental outcome categories. Children in this enriched-likelihood cohort who were breastfed for > 12 months had significantly higher scores on cognitive testing compared to those who were breastfed for 0-3 months. There was no significant difference in ASD symptomatology or ASD risk based on BF duration.

The extended neural architecture of human attachment: An fMRI coordinate-based meta-analysis of affiliative studies

Functional imaging studies and clinical evidence indicate that cortical areas relevant to social cognition are closely integrated with evolutionarily conserved basal forebrain structures and neighboring regions, enabling human attachment and affiliative emotions. The neural circuitry of human affiliation is continually being unraveled as functional magnetic resonance imaging (fMRI) becomes increasingly prevalent, with studies examining human brain responses to various attachment figures. However, previous fMRI meta-analyses on affiliative stimuli have encountered challenges, such as low statistical power and the absence of robustness measures. To address these issues, we conducted an exhaustive coordinate-based meta-analysis of 79 fMRI studies, focusing on personalized affiliative stimuli, including one's infants, family, romantic partners, and friends. We employed complementary coordinate-based analyses (Activation Likelihood Estimation and Signed Differential Mapping) and conducted a robustness analysis of the results. Findings revealed cluster convergence in cortical and subcortical structures related to reward and motivation, salience detection, social bonding, and cognition. Our study thoroughly explores the neural correlates underpinning affiliative responses, effectively overcoming the limitations noted in previous meta-analyses. It provides an extensive view of the neural substrates associated with affiliative stimuli, illuminating the intricate interaction between cortical and subcortical regions. Our findings significantly contribute to understanding the neurobiology of human affiliation, expanding the known human attachment circuitry beyond the traditional basal forebrain regions observed in other mammals to include uniquely human isocortical structures.

Towards Preventative Psychiatry: Concurrent and Longitudinal Predictors of Postnatal Maternal-Infant Bonding

Maternal-infant bonding is important for children's positive development. Poor maternal-infant bonding is a risk factor for negative mother and infant outcomes. Although researchers have examined individual predictors of maternal-infant bonding, studies typically do not examine several concurrent and longitudinal predictors within the same model. This study aimed to evaluate the unique and combined predictive power of cross-sectional and longitudinal predictors of maternal-infant bonding. Participants were 372 pregnant women recruited from an Australian hospital. Data were collected from mothers at antenatal appointments (T0), following their child's birth (T1), and at a laboratory assessment when their child was 5-11-months-old (T2). Poorer bonding at T2 was predicted at T0 by younger maternal age, higher education, and higher antenatal depressive symptoms. Poorer bonding at T2 was predicted at T1 by younger maternal age, higher education, and higher postnatal depressive symptoms. Poorer bonding at T2 was predicted at T2 by younger maternal age, higher education, higher postnatal depression symptoms, higher concurrent perceived social support, and more difficult infant temperament, when controlling for child age at T2. To promote positive maternal-infant bonding, global and targeted interventions in the perinatal period may benefit from targeting maternal psychopathology, perceived lack of social support, and coping with difficult infant temperament.

Maternal outcomes related to Genetic and epigenetic Variation in the oxytocin system: A scoping review

Purpose

In this scoping review, we synthesize the literature on oxytocin and oxytocin receptor genetic and epigenetic variation in relationship to breastfeeding, maternal caregiving behavior, and maternal mental health.

Methods

A literature search was conducted in early 2022, and updated in 2023, utilizing the PRISMA scoping review reporting method, using the following MeSH headings and key terms: oxytocin, oxytocin receptor, genetics, epigenetics, methylation, pregnancy, postnatal, breastfeeding, lactation, mother-infant relations and perinatal outcomes. The search was conducted using PubMed, EMBASE, CINAHL, Google Scholar, SCOPUS, and the Cochrane Library. Inclusion criteria included: human literature which was peer reviewed and found in primary sources, printed in the English language. In addition, the study must have reported genetic/epigenetic data in either the oxytocin or oxytocin receptor gene (maternal or infant up to 12 months after birth) in relation to a breastfeeding, maternal caregiving behavior or a maternal mental health outcome. There was no date limitation. Four authors reviewed studies for eligibility. Data was extracted using a structured data extraction form.

Results

A total of 23 studies met inclusion criteria for this review (breastfeeding n = 4, maternal caregiving behavior n = 7, and maternal mental health n = 16). Seventeen papers reported on oxytocin or oxytocin receptor genotype and nine reported epigenetic associations (namely DNA methylation). These totals are greater than 23, as studies reported on multiple outcomes. One paper assessed the interaction between genotype and methylation. While a number of genotype variations were reported, the single nucleotide polymorphism rs53576 on the oxytocin receptor gene was the most studied. Overall, variation in this polymorphism was related to postnatal depression symptoms. Among numerous epigenetic markers, site -934 was the most studied methylation site, and methylation status was associated with maternal depression and maternal caregiving behavior outcomes. Results suggest that early life experiences impact adult maternal caregiving behaviors and mental health outcomes, and vary based on genetic vulnerability. Breastfeeding outcomes were minimally studied.

Conclusion

This scoping review found that genetic and epigenetic variation at the oxytocin and oxytocin receptor genes were associated with maternal caregiving behavior and mental health, likely through complex gene and environment interactions. The findings suggest that maternal early life experiences and stress impact later caregiving behaviors and mental health in the postnatal period. The findings highlight potential pathways by which environment, experiences, and genes interact to impact maternal caregiving behavior and maternal mental health.

Does the feeding method affect the quality of infant and maternal sleep? A systematic review

Breastfeeding brings many benefits to both mother and infant. Although, many women stop breastfeeding their infants too soon. The perceived association between breastfeeding and sleep may influence their decision to terminate breastfeeding. In our systematic review, we focused on mapping the relationship between infant feeding method and total sleep time (TST), number of nocturnal awakenings, awakenings after sleep onset (WASO) of mothers and infants and sleep quality of mothers. We searched four databases according to selected keywords and inclusion criteria - articles published in peer-reviewed journals between 2012 and 2022; English language; a sample consisting of mothers, infants, or both (without psychiatric and health problems); a comparison of the sleep quality of breastfed and formula-fed children or breastfeeding and formula-fed mothers. We read 260 full texts of selected articles. A total of 35 articles were included in this review. Due to significant heterogeneity, meta-analysis was not possible to accomplish. The results are processed according to narrative synthesis. Most studies agree that breastfed infants wake up more often at night. Total sleep time and time spent awake during the night (WASO) did not differ between breastfed and non-breastfed infants. We observed identical results in sleep variables among mothers. Additionally, there was no difference in maternal sleep quality. The synthesis revealed that the results may have differed due to using subjective, objective methods or the infant's age. It is important to remember that night waking is a more complex concept. Infants wake for many reasons, not just due to breastfeeding. The narrative synthesis indicated that the chosen study design, measurement method, the variables, and the infant's age could influence outcomes. In addition, other variables appeared that may affect the entire process. Therefore, we recommend that attention be paid to this in future studies.

Longitudinal changes in attention bias to infant crying in primiparous mothers

Introduction

Infant stimuli attract caregiver attention and motivate parenting behavior. Studies have confirmed the existence of attentional bias toward infant face stimuli; however, relatively little is known about whether attentional bias exists for infant cry stimuli, which are as important as faces in child-rearing situations. Furthermore, scarce longitudinal evidence exists on how attentional bias toward infant crying changes through the postpartum period.

Methods

In the present study, we conducted an experiment to assess bias toward infant crying at two postpartum time points: at Time 1 (Mean = 75.24 days), 45 first-time mothers participated and at Time 2 (Mean = 274.33 days), 30 mothers participated. At both time points, the mothers participated in a Stroop task with infant crying and white noise as the stimuli. They were instructed to answer the color out loud as quickly and accurately as possible, while ignoring the sound. Four types of audio stimuli were used in this task (the cry of the mother's own infant, the cry of an unfamiliar infant, white noise matched to the cry of the mother's own infant, and white noise matched to the cry of an unfamiliar infant), one of which was presented randomly before each trial. Response time and the correct response rate for each condition were the dependent variables.

Results

For response time, the main effect of familiarity was significant, with longer response times when the participant's infant's cry was presented. In addition, response times were lower at Time 2 than at Time 1 in some conditions in which crying was presented.

Discussion

The results suggest that mothers may be less disturbed by infant crying as they gain more experience. Elucidating the characteristics of postpartum mothers' changes in cognitive performance related to infants' cries would be useful in fundamental and applied research to understand the process of parents' adaptation to parenting.

In the mind of the beholder: The effects of familiarisation on the perception of atypical infant facial configurations

Infant facial attractiveness is an important facilitator for adult-infant caregiving behaviour. Disruption to typical infant facial configurations can, however, attenuate their perceived attractiveness, as rated by adult observers. Previous research has either focused on how ratings are affected by observer characteristics (e.g., male/female), or alterations to infant faces, either experimentally, or naturalistically induced, such as the presence of a cleft lip. Little research has however been conducted on the effects of observer experience on adult ratings of infant facial attractiveness. Such effects could inform clinical work and policies aimed at promoting positive perception of facial malformations. The present study thus explored the effects of familiarisation on how typical and atypical infant facial configurations are evaluated by adults. We recruited two groups of female participants and compared their subjective attractiveness ratings of infant faces (24 typical and 24 cleft-affected), at baseline, and at one-week post-test. Between the two assessments, one group (n = 41) underwent a week-long training phase, where they were familiarised with cleft lip/palate-related visual and informational stimuli, while the control group (n = 44) received no training. Significantly higher ratings were provided for faces of typically developing versus cleft-affected infants by both groups of participants at baseline. At post-test, this pattern of ratings was repeated in participants belonging to the control group, while familiarised participants showed an increase, compared to baseline, in their ratings of cleft-affected faces and no difference between their evaluation of the latter and that of typically developing faces. These findings extend our understanding of the observer's experience in the evaluation of infant faces, beyond the effects of the structural characteristics of the observed faces. Results also highlight familiarity as a potentially protective influence against the negative consequences of alterations to typical facial configurations, suggesting avenues for intervention in supporting adult caregivers in the context of neonatal facial malformations.

The evolved nest, oxytocin functioning, and prosocial development

Prosociality, orientation to attuned, empathic relationships, is built from the ground up, through supportive care in early life that fosters healthy neurobiological structures that shape behavior. Numerous social and environmental factors within early life have been identified as critical variables influencing child physiological and psychological outcomes indicating a growing need to synthesize which factors are the most influential. To address this gap, we examined the influence of early life experiences according to the evolved developmental niche or evolved nest and its influence on child neurobiological and sociomoral outcomes, specifically, the oxytocinergic system and prosociality, respectively. To-date, this is the first review to utilize the evolved nest framework as an investigatory lens to probe connections between early life experience and child neurobiological and sociomoral outcomes. The evolved nest is comprised of characteristics over 30 million years old and is organized to meet a child's basic needs as they mature. Converging evidence indicates that humanity's evolved nest meets the needs of a rapidly developing brain, optimizing normal development. The evolved nest for young children includes soothing perinatal experiences, breastfeeding, positive touch, responsive care, multiple allomothers, self-directed play, social embeddedness, and nature immersion. We examined what is known about the effects of each evolved nest component on oxytocinergic functioning, a critical neurobiological building block for pro-sociomorality. We also examined the effects of the evolved nest on prosociality generally. We reviewed empirical studies from human and animal research, meta-analyses and theoretical articles. The review suggests that evolved nest components influence oxytocinergic functioning in parents and children and help form the foundations for prosociality. Future research and policy should consider the importance of the first years of life in programming the neuroendocrine system that undergirds wellbeing and prosociality. Complex, interaction effects among evolved nest components as well as among physiological and sociomoral processes need to be studied. The most sensible framework for examining what builds and enhances prosociality may be the millions-year-old evolved nest.

Breastfeeding and Bonding: A Surprising Role of Breastfeeding Difficulties

Aims: To explore the role of breastfeeding difficulties in bonding. Background: Studies published to date yielded varying results regarding the relationship between breastfeeding and bonding. In qualitative studies, mothers often describe breastfeeding as a bonding experience and regard breastfeeding difficulties as challenging. Only one quantitative study explored the impact of breastfeeding difficulties on bonding. Methods: A cross-sectional method was used and a self-report questionnaire was administered to a convenience sample of mothers with infants aged 0-6 months. Results: We found that having problem-free breastfeeding versus breastfeeding associated with breastfeeding difficulties led to a difference in bonding quality. Experiencing any breastfeeding difficulties was associated with bonding impairment (p = 0.000, r = 0.174), especially in cases of breast engorgement (p = 0.016, r = 0.094), a nonlatching baby (p = 0.000, r = 0.179), perceived low milk supply (p = 0.004, r = 0.112), and fussing at the breast (p = 0.000, r = 0.215). We also found a difference in bonding impairment between exclusively breastfeeding and exclusively bottle-feeding mothers (p = 0.001), but only when taking into account breastfeeding difficulties. Conclusions: Breastfeeding is a complex interaction that can be associated with mother-infant bonding in various ways. We found that breastfeeding difficulties were linked to bonding impairment, whereas exclusive breastfeeding without the presence of breastfeeding difficulties was not. Strategies to help achieve exclusive breastfeeding and prevent and resolve breastfeeding difficulties may help mothers fulfill the bonding potential with their infant.

Breastfeeding at Any Cost? Adverse Effects of Breastfeeding Pain on Mother-Infant Behavior

Breast milk is considered the ideal infant nutrition, and medical organizations encourage breastfeeding worldwide. Moreover, breastfeeding is often perceived as a natural and spontaneous socio-biological process and one of the fundamental roles of new mothers. While breastfeeding is beneficial, little scientific consideration has been given to its potential psychological challenges. Here, we investigate the phenomenon of breastfeeding pain in mothers and its association with maternal and infant behavioral regulation. During the postpartum weeks, the mother-infant dyad can be considered one allostatic unit directed at infant regulation and development. We hypothesize that pain comprises an allostatic challenge for mothers and will thus impair the capacity for dyadic regulation. To test this, we recruited 71 mothers with varying levels of breastfeeding pain and videotaped them with their infants (2-35 weeks old) during spontaneous face-to-face interactions. We quantified the individual differences in dyadic regulation by behaviorally coding the second-by-second affective expressions for each mother and infant throughout their interactions. We tested the extent to which breastfeeding pain alters affect regulation during mother-infant interactions. We discovered that mothers with severe breastfeeding pain express less affective expressions and less infant-directed gaze during interactive moments of engagement and play than mothers with no or moderate pain. Moreover, infants of mothers experiencing pain during breastfeeding express less affective expressions and more mother-directed gaze while interacting with their mothers than infants of mothers who are not in pain. This demonstrates that the allostatic challenge of maternal pain interferes with the behavioral regulation of both mothers and infants. Since the mother-infant dyad is a codependent allostatic unit, the allostatic challenges of one partner can impact the dyad and thus potentially impact child development, bonding, and mother and infant well-being. The challenges of breastfeeding should be considered in addition to the nutritional advances.

Cortical and subcortical morphological alterations in postpartum depression

Postpartum depression (PPD) is the most common postpartum psychiatric disorder, which can negatively affect both mothers and their offspring. Although the functional changes of PPD have been extensively studied, little is known about its structural abnormalities. This study aimed to examine the cortical and subcortical morphological abnormalities in PPD. High resolution T1 structural MRI data of 29 PPD women and 23 matched healthy postpartum women (HPW) were included in this study. Using surface-based morphometry, we examined the differences between the PPD and HPW group in the cortical thickness, local gyrification index and shape changes of deep gray matter nuclei. Compared with the HPW group, women with PPD showed significantly increased cortical thickness in the left superior frontal gyrus, cuneus and right lingual gyrus and fusiform gyrus, which correlated marginally with the EPDS scores of these subjects. In addition, women with PPD showed significant regional inflation in the right pallidum compared with the HPW group. These findings provided further evidence for the structural brain abnormalities in PPD.

Beliefs and Norms Influencing Initiation and Sustenance of Exclusive Breastfeeding: Experiences of Mothers in Primary Health Care Facilities in Ermelo, South Africa

Exclusive breastfeeding (EBF) is not a norm in many communities in South Africa despite the World Health Organizations' recommendations for EBF in the first six months of infant's life. Thus, South Africa continues to observe suboptimal and poor practices of EBF. The purpose of the study was to explore the experiences of mothers who are HIV-positive and negative on EBF and examine the extent to which initiation and sustenance of EBF is influenced by cultural beliefs, societal norms, and family norms and practices in Mpumalanga Province. Three focus group discussions and twelve in-depth interviews were conducted among thirty mothers who were purposively selected during their visits to the facilities for childcare services. Interviews were audiotaped, transcribed verbatim, and transcripts were analysed through thematic analysis using NVivo version 10. Mothers were aged between 18 and 42 years, most were unemployed and were living in poor sociodemographic backgrounds in extended family households. We found evidence of factors that influence the decision to EBF and mix feed infants among mothers. Traditional and cultural beliefs and norms that exist within their communities informed decisions mothers took to EBF. These beliefs existed alongside mothers' opinions on breastfeeding (BF) and HIV infection, as well as the fears of harming the baby through HIV infection, leading to early cessation of BF. Mothers were also advised by family members, friends, and even some healthcare workers to use traditional medicines while BF. The association of EBF with sagging breasts and weight loss as well as discomfort with public BF are personal beliefs that influenced initiation and early cessation of EBF. Breastfeeding messages ought to be context specific to improve the knowledge, understanding, acceptance and practice of EBF among HIV-positive and negative mothers. Culturally appropriate counselling messages that address the known cultural practices of the populations affected are essential to changing the beliefs and norms of the communities including extended families of EBF mothers.

Functional near-infrared spectroscopy is a useful tool for multi-perspective psychobiological study of neurophysiological correlates of parenting behaviour

The quality of the relationship between caregiver and child has long-term effects on the cognitive and socio-emotional development of children. A process involved in human parenting is the bio-behavioural synchrony that occurs between the partners in the relationship during interaction. Through interaction, bio-behavioural synchronicity allows the adaptation of the physiological systems of the parent to those of the child and promotes the positive development and modelling of the child's social brain. The role of bio-behavioural synchrony in building social bonds could be investigated using functional near-infrared spectroscopy (fNIRS). In this paper we have (a) highlighted the importance of the quality of the caregiver-child relationship for the child's cognitive and socio-emotional development, as well as the relevance of infantile stimuli in the activation of parenting behaviour; (b) discussed the tools used in the study of the neurophysiological substrates of the parental response; (c) proposed fNIRS as a particularly suitable tool for the study of parental responses; and (d) underlined the need for a multi-systemic psychobiological approach to understand the mechanisms that regulate caregiver-child interactions and their bio-behavioural synchrony. We propose to adopt a multi-system psychobiological approach to the study of parental behaviour and social interaction.

Repetitive negative thinking during pregnancy and postpartum: Associations with mental health, inflammation, and breastfeeding

INTRODUCTION

Repetitive negative thinking (RNT) is a transdiagnostic feature that predicts increased mental health risks, inflammation, and reduced engagement in health promoting behaviors. Depression, anxiety, stress, inflammation, higher body mass index (BMI), and low engagement in health behaviors are associated with adverse outcomes during pregnancy as well as postpartum. However, there is limited literature on the associations between RNT and these contributing factors in the perinatal period, an at-risk time during which women may benefit from clinical interventions directed at RNT.

METHODS

This study examined the contribution of RNT to inflammation [interleukin (IL)-6] and breastfeeding duration through mediating indicators of mental health and BMI. Behavioral and biological assessments occurred during late pregnancy as well as at 4-6 weeks, 4 months, 8 months, and 12 months postpartum.

RESULTS

RNT was positively associated with depressive symptoms, anxiety, and perceived stress (ps ≤ .001) at each assessment timepoint, with the strongest associations observed at the pregnancy assessment and significant, but attenuated, associations during postpartum (ps < .01). In modeling of the association between RNT and IL-6, the indirect effect of BMI was significant at each timepoint (95%CIs 0.0013, 0.0052). Women with lower RNT exhibited longer breastfeeding duration (p = .02). These effects were not significantly mediated by mental health indicators.

CONCLUSIONS

Clinically meaningful relationships, in which RNT predicts mental health, inflammation, and health behavior engagement during pregnancy and postpartum were observed. Clinical interventions to reduce RNT may have unique benefits this time.

LIMITATIONS

Further research is warranted to determine if therapies to reduce RNT confer unique benefits for maternal and child health.

Collateral benefits from a school-readiness intervention on breastfeeding: A cross-domain impact evaluation

This study evaluated the collateral, or unanticipated, impacts of Smart Beginnings (SB), a two-site, tiered intervention designed to promote responsive parenting and school readiness, on breastfeeding intensity in a low-income sample. Impact analyses for the SB intervention were conducted using an intent-to-treat design leveraging a two-arm random assignment structure. Mothers assigned to the SB intervention group were more than three times more likely to give breastmilk as the only milk source at infant age 6 months than mothers assigned to the control group at one site, an effect not evident at the other study site. As development and growth are the two most salient domains of child health, understanding how interventions impact subsequent parenting practices across both domains is critical to address long-term economic and racial/ethnic disparities. Implications of the findings are discussed for improving the efficacy of interventions based on paediatric primary care.

Endogenous oxytocin levels in extracted saliva elevates during breastfeeding correlated with lower postpartum anxiety in primiparous mothers

Background

Breastfeeding in the early postpartum period is expected to have mental benefits for mothers; however, the underlying psychobiological mechanisms remain unclear. Previously, we hypothesized that the release of oxytocin in response to the suckling stimuli during breastfeeding would mediate a calming effect on primiparous mothers, and we examined salivary oxytocin measurements in primiparous mothers at postpartum day 4 using saliva samples without extraction, which was erroneous. Thus, further confirmation of this hypothesis with a precise methodology was needed.

Methods

We collected saliva samples at three time points (baseline, feeding, and post-feeding) to measure oxytocin in 24 primiparous mothers on postpartum day 2 (PD2) and 4 (PD4) across the breastfeeding cycle. Salivary oxytocin levels using both extracted and unextracted methods were measured and compared to determine the qualitative differences. State and trait anxiety and clinical demographics were evaluated to determine their association with oxytocin changes.

Results

Breastfeeding elevated salivary oxytocin levels; however, it was not detected to a significant increase in the extraction method at PD4. We found a weak but significant positive correlation between changes in extracted and unextracted oxytocin levels during breastfeeding (feeding minus baseline); there were no other significant positive correlations. Therefore, we used the extracted measurement index for subsequent analysis. We showed that the greater the increase in oxytocin during breastfeeding, the lower the state anxiety, but not trait anxiety. Mothers who exclusively breastfed at the 1-month follow-up tended to be associated with slightly higher oxytocin change at PD2 than those who did not.

Conclusions

Breastfeeding in early postpartum days could be accompanied by the frequent release of oxytocin and lower state anxiety, potentially contributing to exclusive breastfeeding.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12884-022-05026-x.

Trait coping styles and the maternal neural and behavioral sensitivity to an infant

During the postpartum period, new mothers experience drastic changes in their body, brain, and life circumstances. Stress from the emotional and physical demands of caring for an infant is associated with negative mood and parenting outcomes. The use of active coping strategies can increase mothers’ resilience during the postpartum period. However, little is known about the association between coping styles and maternal brain responses to infant cues. In the current study, we examined the associations among trait coping style, maternal brain responses, and behavioral sensitivity in a socioeconomically diverse sample of first-time mothers (N = 59). The use of more active trait coping strategies compared to passive coping strategies was associated with increased brain responses to infant cry sounds in brain regions that are critically involved in motivation and emotion regulation—substantia nigra, anterior cingulate gyrus, and inferior frontal gyrus. Increased brain activations in the midbrain and anterior cingulate gyrus were further associated with higher levels of maternal sensitivity observed during interactions with the infant. Thus, the findings provide support for mothers’ use of more active coping styles to promote neural and behavioral resilience for a positive transition to parenthood.

Maternal dopamine encodes affective signals of human infants

Mothers are highly responsive to their offspring. In non-human mammals, mothers secrete dopamine in the nucleus accumbens (NAcc) in response to their pups. Yet, it is still unknown which aspect of the offspring behavior elicits dopaminergic responses in mothers. Here, we tested whether infants' affective signals elicit dopaminergic responses in the NAcc of human mothers. First, we conducted a behavioral analysis on videos of infants' free play and quantified the affective signals infants spontaneously communicated. Then, we presented the same videos to mothers during a magnetic resonance-positron emission tomography scan. We traced the binding of [11C]raclopride to free D2/3-type receptors to assess maternal dopaminergic responses during the infant videos. When mothers observed videos with many infant signals during the scan, they had less [11C]raclopride binding in the right NAcc. Less [11C]raclopride binding indicates that less D2/3 receptors were free, possibly due to increased endogenous dopamine responses to infants' affective signals. We conclude that NAcc D2/3 receptors are involved in maternal responsiveness to affective signals of human infants. D2/3 receptors have been associated with maternal responsiveness in nonhuman animals. This evidence supports a similar mechanism in humans and specifies infant-behaviors that activate the maternal dopaminergic system, with implications for social neuroscience, development and psychopathology.

Maternal Milk Provision in the Neonatal Intensive Care Unit and Mother–Infant Emotional Connection for Preterm Infants

Maternal milk (MM) intake during neonatal intensive care unit (NICU) hospitalization is associated with improved neurodevelopment in preterm infants. Underlying mechanisms may include stronger mother–infant emotional connection. This paper examines associations between MM provision in the NICU with maternal connection to her infant using three factors validated in our sample: maternal sensitivity, emotional concern, and positive interaction/engagement. We studied 70 mothers of infants born <1500 g and/or <32 weeks’ gestation. Associations between MM provision and mother–infant connection were modeled using median regression adjusted for clustering. Mothers who provided exclusive MM (i.e., 100% MM, no other milk) reported higher levels of maternal sensitivity by a median score of 2 units (β = 2.00, 95% CI: 0.76, 3.24, p = 0.002) than the mixed group (i.e., MM < 100% days, other milk ≥1 days), as well as greater emotional concern (β = 3.00, 95% CI: −0.002, 6.00, p = 0.05). Among mothers of very preterm infants, greater milk provision was associated with greater maternal sensitivity, but also with greater emotional concern about meeting the infant’s needs. These findings highlight the importance of supporting MM provision and early infant care as an integrated part of lactation support. The findings may also provide insight into links between MM provision in the NICU and infant neurodevelopment.

Does breastfeeding account for the association between maternal sensitivity and infant cognitive development in a large, nationally representative cohort?

Background

Previous research has established that exposure to high maternal sensitivity is positively associated with advances in infant cognitive development. However, there are many fixed and modifiable factors that influence this association. This study investigates whether the association between maternal sensitivity and infant cognitive development in the first year of life is accounted for by other factors, such as breastfeeding, maternal depressive symptoms, maternal alcohol use, infant birth weight or demographic covariates.

Methods

Using data from the Early Childhood Longitudinal Study-Birth (ECLS-B) Cohort, a nationally representative sample of U.S. born children, multi-variable regression analyses was used to examine whether breastfeeding, maternal depressive symptoms and alcohol use were associated with maternal sensitivity, as measured by the Nursing Child Assessment Teaching Scale (NCATS), and with infant cognitive development, as measured by the Bayley Scales of Infant Development, Short Form, Research Edition, after controlling for demographic covariates (infant sex, maternal age, education, race/ethnicity, income, parity, family structure) and infant birth weight.

Results

Breastfeeding, depressive symptoms and alcohol use were not associated with maternal sensitivity scores after controlling for demographic covariates and infant birth weight. However, breastfeeding (β = .079, p < .001), depressive symptoms (β = −.035, p < .05), and maternal sensitivity (β = .175, p < .001) were each significantly associated with infant cognitive development scores, even after controlling for demographic covariates and birthweight (R² = .053, p < .001). The association between maternal sensitivity and infant cognitive development did not attenuate after adjusting for breastfeeding. Instead, both sensitivity and breastfeeding independently contributed to higher infant cognitive development scores.

Conclusion

Maternal sensitivity and breastfeeding are separate means to advancing infant cognitive development. This study is significant because it is the first to examine breastfeeding, maternal depressive symptoms and alcohol use together, upon the association between maternal sensitivity and infant cognitive development, after adjusting for demographic covariates and infant birthweight. Maternal sensitivity, a measurable quality, advances infants’ cognitive development. Moreover, sensitivity and breastfeeding had independent effects upon cognitive development after controlling for multiple fixed and modifiable covariates. Understanding factors impacting the association between sensitivity and infant cognitive development provide avenues for developing more effective parenting interventions.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12887-022-03133-4.

Adult attachment style moderates the effect of oxytocin on neural responses to infant emotional faces

Oxytocin (OT) is known for its positive influence on maternal motivation and behavior, however, the effects of intranasal oxytocin (IN-OT) on neural activity during the perception of infant stimuli are often inconsistent. These discrepancies further reveal the need to take into account individual differences in IN-OT research. The present study aims to examine whether the effects of IN-OT on maternal-related neural responses to infant faces were moderated by participants' attachment style. Using a between-groups, double-blind, placebo-controlled design, 65 nulliparous females were randomly assigned to groups receiving a single dose of 24 IU oxytocin or a placebo via intranasal administration. The neural responses of participants were assessed during a facial recognition task with joy, neutral, and crying infant faces. The results indicated that females with high levels of attachment anxiety exhibited decreased right amygdala activity in response to infant joy faces and decreased bilateral insula activity in response to infant crying faces following IN-OT. Meanwhile, IN-OT enhanced bilateral amygdala and left inferior orbital frontal cortex (OFC) activity in response to infant crying faces in females with high levels of attachment avoidance. In addition, some beneficial effects of IN-OT were also observed in females with low levels of attachment avoidance or anxiety. Our findings demonstrated that the beneficial effects of IN-OT on neural responses to infant faces may depend on individual differences in adult attachment style, thereby contributing to our understanding of the role of OT in maternal caregiving.

Reasons mothers bedshare: A review of its effects on infant behavior and development

Bedsharing is controversial for nighttime caregiving in the U.S. today, as in most of the West. However, from the standpoint of evolutionary pediatrics, anthropology, and cultural psychology, bedsharing is not controversial at all, representing the context for human infant evolution and conferring a host of physiological benefits to the infant as well as the mother. In an effort to understand the rise in Western bedsharing in recent decades (and following Ball, 2002; McKenna & Volpe, 2007), Salm Ward (2015) systematically reviewed the literature on mother-infant bedsharing and identified ten reasons why mothers choose to bedshare: (1) breastfeeding, (2) comforting for mother or infant, (3) better/more sleep for infant or parent, (4) monitoring, (5) bonding/ attachment, (6) environmental reasons, (7) crying, (8) cultural or familial traditions, (9) disagree with danger, and (10) maternal instinct. The current paper offers the "review behind the review," highlighting the scientific evidence behind the reasons mothers give for their decision to bedshare, focusing on how mothers' decisions about infant sleep location influence infant behavior and development.

The association between sleep and empathy in young preschoolers: A population study

Sleep is vital for children's early socio-emotional development, particularly empathy. This study aimed to explore the associations between sleep and empathy in young preschoolers. A sample of 23,259 preschoolers (4.3 ± 0.3 years) at the entry year of preschool was recruited as part of the Shanghai Children's Health, Education and Lifestyle Evaluation-Preschool (SCHEDULE-P) study. Caregivers reported on child sleep, affective empathy, and cognitive empathy through the Children's Sleep Habits Questionnaire and the Griffith Empathy Measure. Ordinary least-square regression and quantile regression were performed for the associations between sleep and empathy. Sex differences were also investigated. Night sleep duration was negatively associated with affective empathy (β = -0.35, p < 0.001), and positively associated with cognitive empathy (β = 0.41, p < 0.001). Longer nap duration was associated with higher affective empathy (β = 0.28, p < 0.001). Sleep disturbances were positively associated with affective empathy (β = 0.04, p < 0.001) and negatively associated with cognitive empathy (β = -0.09, p < 0.001). These associations were generally stronger in children at higher empathy quantiles and also those at the 10^th cognitive empathy quantile. The associations between sleep and affective empathy were mainly contributed by girls, and were more common in boys in terms of cognitive empathy, particularly at the 10^th and the 30^th quantiles. In conclusion, longer night sleep duration and fewer sleep disturbances are associated with a more mature empathy pattern in young preschoolers. The associations are more prominent in children at the higher end of the empathy spectrum, and vary by sex. These findings highlight the importance to promote sleep health in young children for optimal socio-emotional development.

Neural Representation of the Parent-Child Attachment from Infancy to Adulthood

Attachment theory is built on the assumption of consistency; the mother–infant bond is thought to underpin the life-long representations individuals construct of attachment relationships. Still, consistency in the individual’s neural response to attachment-related stimuli representing his or her entire relational history has not been investigated. Mothers and children were followed across two decades and videotaped in infancy (3–6 months), childhood (9–12 years) and young adulthood (18–24 years). In adulthood, participants underwent functional magnetic resonance imaging while exposed to videos of own mother–child interactions (Self) vs unfamiliar interactions (Other). Self-stimuli elicited greater activations across preregistered nodes of the human attachment network, including thalamus-to-brainstem, amygdala, hippocampus, anterior cingulate cortex (ACC), insula and temporal cortex. Critically, self-stimuli were age-invariant in most regions of interest despite large variability in social behavior, and Bayesian analysis showed strong evidence for lack of age-related differences. Psycho–physiological interaction analysis indicated that self-stimuli elicited tighter connectivity between ACC and anterior insula, consolidating an interface associating information from exteroceptive and interceptive sources to sustain attachment representations. Child social engagement behavior was individually stable from infancy to adulthood and linked with greater ACC and insula response to self-stimuli. Findings demonstrate overlap in circuits sustaining parental and child attachment and accord with perspectives on the continuity of attachment across human development.

Dysphoric Milk Ejection Reflex: The Psychoneurobiology of the Breastfeeding Experience

Breastfeeding, given its biochemical and physiological basis, is known for its many benefits for both the lactating mother and the infant. Among the many challenges new breastfeeding mothers experience is the feeling of aversion in response to their newborn's suckling which has been termed dysphoric milk-ejection reflex (D-MER). Characterized by intense feelings of dysphoria which may eventually interfere with the mother's ability to breastfeed regularly, evidence suggests both the neurobiological and psychological basis of D-MER in an attempt to explain its complexity. Biologically, breastfeeding is expressed by the intracerebral release of oxytocin, an increased expression of oxytocin receptors in specific brain regions, increased mesocorticolimbic reward region activation, the secretion of prolactin and possibly the inhibition of dopamine. Hence, different theories explain D-MER in terms of disrupted neurotransmitter and hormonal activity. Breastfeeding has also proven to influence mood and stress reactivity in nursing mothers with a potential link with postpartum depression. Psychological theories attempt to explain D-MER from a sociopsychosexual lense shedding light on the significance of mother-infant attachment, the sexualization of the female body and the motherhood experience as a developmental stage in a woman's lifespan. The aim of this review is to provide a literature update of D-MER incorporating both neurobiological and psychological theories calling for raising awareness about the complexity of breastfeeding and for the need for mother-centered interventions for the management of D-MER and other postpartum-specific conditions.

Type of Milk Feeding and Introduction to Complementary Foods in Relation to Infant Sleep: A Systematic Review

Inconsistent conclusions from infant sleep and feeding studies may influence parents feeding-related decisions. This study aimed to systematically review the existing literature on infant sleep and its relation to the timing of introduction to complementary foods and type of milk feeding to better understand their role(s) in infant sleep. Cohort, longitudinal, cross-sectional studies, and controlled trials were identified using online searches of five databases up to April 2020. Twenty-one articles with a total of 6225 infants under 12 months-of-age were eligible. Exclusively breastfed infants (≤6 months-of-age) had a greater number of night wakings, but most studies (67%) reported no difference in night-time and 24 h sleep duration compared to formula-fed infants. However, after 6 months-of-age, most studies (>65%) reported breastfed infants to sleep less in the night-time and over 24 h compared to formula-fed infants. Furthermore, studies reported no association between the timing of introduction to complementary foods and infant sleep duration (<12 months-of-age). Future studies using standardized methodologies and definitions, transdisciplinary expertise, and longitudinal design are required to better understand the complex role of feeding on sleep.

Mothers are more sensitive to infant cues after breastfeeding compared to bottle-feeding with human milk

The belief that breastfeeding promotes maternal bonding is widely held by both the public and professional health organizations. Yet to our knowledge, all research examining the link between breastfeeding and maternal behavior in humans has been correlational, limiting our ability to draw causal conclusions. In many mammals, the hormone prolactin, which is central to milk production, rises in response to each breastfeeding session and promotes maternal sensitivity, yet there is a dearth of research in human mothers. To fill these research gaps, we randomly assigned 28 breastfeeding mothers to either breastfeed in the lab or feed their infants previously expressed breastmilk in a bottle before participating in a video-recorded free play session with their infant. Plasma prolactin was measured 40 min after the start of the feeding session and video observations were coded for maternal sensitivity. We found that women randomly assigned to breastfeed were more sensitive to infant cues than women randomly assigned to bottle-feed. Prolactin levels did not differ between feeding groups, although prolactin was positively correlated with maternal sensitivity. Our results suggest that feeding milk directly from the breast (compared to bottle-feeding) increases maternal sensitivity towards infants, at least in the short term.

Early life maltreatment affects intrinsic neural function in mothers

Early life maltreatment (ELM) has an impact on brain functions involved in parenting and is associated with impaired maternal sensitivity. Here, we investigated the influence of ELM on intrinsic neural function and its associations with maternal sensitivity in mothers without a current episode of a mental disorder. Twenty-seven mothers with ELM and 29 mothers without ELM were examined using resting-state functional magnetic resonance imaging, followed by Amplitude of Low Frequency Fluctuations, regional homogeneity and seed-based functional connectivity analyses. Videotaped interactions between mothers and their school-aged children were conducted to assess maternal sensitivity based on the Emotional Availability Scales. Regional and functional connectivity measures were used to investigate associations between intrinsic activity and emotional availability. Mothers with ELM showed reduced maternal sensitivity and lower intrinsic neural activity in the right superior frontal gyrus, the left precuneus, the left middle occipital gyrus, and the parietal cortex (left angular and right supramarginal gyrus) compared to mothers without ELM (p < .001, whole-brain). Amplitude of Low Frequency Fluctuations in the superior frontal gyrus was positively associated with maternal sensitivity across all participants (p = .002). The data suggest a behavioral and neural signature of ELM even in currently mentally healthy mothers. In particular, effects of ELM were found in distinct brain regions involved in social cognition and executive control. These ELM-related alterations may be associated with maternal behavior.

A soft baby carrier intervention enhances amygdala responses to infant crying in fathers: A randomized controlled trial

New fathers may grow into their parental role through active involvement in childcare. Spending time in physical contact with the child may promote an adaptive transition to fatherhood. In this randomized controlled trial, we tested the effects of a baby carrier intervention on fathers' hormonal and neural functioning. Using functional magnetic resonance imaging (fMRI), we examined whether infant carrying affects neural reactivity to infant crying in first-time fathers, taking into account the role of the hormone oxytocin as a mediating mechanism and fathers' own childhood experiences as a potential moderating factor. Sixty first-time fathers (infant age M = 11.18 weeks, SD = 2.08) were randomly assigned to a baby carrier intervention group (n = 32 fathers) or a control group (n = 28 fathers). Fathers in the intervention group were instructed to use a baby carrier for three weeks, whereas fathers in the control group were instructed to use a baby seat. Before and after the intervention salivary oxytocin was measured and neural reactivity to infant crying was assessed using fMRI. Results showed that the infant carrier intervention increased amygdala reactivity to infant crying compared to the infant seat users. This effect was most pronounced in fathers with experiences of childhood abuse. The carrier intervention did not affect fathers' oxytocin levels. Our findings indicate that spending time in physical contact with the infant may promote attention to and accurate perception of infant signals, in particular in fathers with more adverse childhood experiences. Soft baby carriers may, therefore, facilitate an adaptive transition to fatherhood.

Postpartum Depression Is Associated With Altered Neural Connectivity Between Affective and Mentalizing Regions During Mother-Infant Interactions

Although there has been growing interest in mood-related neural alterations in women in the initial weeks postpartum, recent work has demonstrated that postpartum depression often lingers for months or years following birth. However, research evaluating the impact of depression on maternal brain function during mother-infant interactions in the late postpartum period is lacking. The current study tested the hypothesis that depressive symptoms at 12-months postpartum are associated with neural alterations in affective and social neural regions, using near-infrared spectroscopy during in vivo mother-infant interactions. Participants were 23 birth mothers of 12-month-old infants (60% boys). While undergoing near-infrared spectroscopy, mothers engaged in an ecologically valid interactive task in which they looked at an age-appropriate book with their infants. Mothers also reported on their depressive symptoms in the past week and were rated on their observed levels of maternal sensitivity during mother-infant play. Greater depressive severity at 12-months postpartum was related to lower connectivity between the right temporoparietal junction and the lateral prefrontal cortex, but greater connectivity between the right temporoparietal junction and anterior medial prefrontal cortex during mother-infant interaction. Given the putative functions of these neural regions within the maternal brain network, our findings suggest that in the context of depression, postpartum mothers' mentalizing about her infants' thoughts and feelings may be related to lower ability to express and regulate her own emotions, but greater ability to engage in emotional bonding with her infant. Future work should explore how connectivity among these regions is associated with longitudinal changes in maternal behavior, especially in the context of changes in mothers' depressive symptoms (e.g., with treatment) over time.

T3 is linked to stress-associated reduction of prolactin in lactating women

The relationship between stress responses and lactation is bidirectional. Breastfeeding confers many benefits to maternal health, including attenuated hypothalamic-pituitary-adrenal axis responsiveness to stress. However, increased stress burden can impair lactation. The mechanisms that underlie these relationships are poorly understood. The present study aimed to compare breastfeeding habits, as well as subjective and objective measures of stress, in employed and non-employed lactating women and assess the relationships between these measures and prolactin (PRL), thyroid hormones (thyroid-stimulating hormone, triiodothyronine [T3] and thyroxine), vasopressin and cortisol levels. A dexamethasone suppression test was also administered to determine the sensitivity of the hypothalamic-pituitary-adrenal axis to negative-feedback. We report that lactating employed women had lower breastfeeding rates and lower PRL than lactating non-employed women. They also had a significantly higher stress burden, indicated by elevations in blood pressure and evening cortisol, relative to lactating non-employed women. In regression analyses that controlled for feeding modality and breastfeeding duration, we found these factors differentially affected PRL in the two groups and there were significant differences in PRL across groups that were not accounted for by these factors. A mediation regression analysis suggested that group differences in PRL were best explained by differences in T3 and income levels, rather than breastfeeding duration or other variables. Our data fit a speculative model in which elevated maternal stress increases cortisol, which suppresses T3, leading to decreased PRL. The decreases in PRL are associated with higher rates of bottlefeeding, which may further contribute to decreased PRL.

Reported maternal childhood maltreatment experiences, amygdala activation and functional connectivity to infant cry

Maternal childhood maltreatment experiences (CMEs) may influence responses to infants and affect child outcomes. We examined associations between CME and mothers' neural responses and functional connectivity to infant distress. We hypothesized that mothers with greater CME would exhibit higher amygdala reactivity and amygdala-supplementary motor area (SMA) functional connectivity to own infant's cries. Postpartum mothers (N = 57) assessed for CME completed an functional magnetic resonance imaging task with cry and white-noise stimuli. Amygdala region-of-interest and psychophysiological interaction analyses were performed. Our models tested associations of CME with activation and connectivity during task conditions (own/other and cry/noise). Exploratory analyses with parenting behaviors were performed. Mothers with higher CME exhibited higher amygdala activation to own baby's cries vs other stimuli (F1,392 = 6.9, P < 0.01, N = 57) and higher differential connectivity to cry vs noise between amygdala and SMA (F1,165 = 22.3, P < 0.001). Exploratory analyses revealed positive associations between both amygdala activation and connectivity and maternal non-intrusiveness (Ps < 0.05). Increased amygdala activation to own infant's cry and higher amygdala-SMA functional connectivity suggest motor responses to baby's distress. These findings were associated with less intrusive maternal behaviors. Follow-up studies might replicate these findings, add more granular parenting assessments and explore how cue processing leads to a motivated maternal approach in clinical populations.

The Application of Connectome-Based Predictive Modeling to the Maternal Brain: Implications for Mother-Infant Bonding

Maternal bonding early postpartum lays an important foundation for child development. Changing brain structure and function during pregnancy and postpartum may underscore maternal bonding. We employed connectome-based predictive modeling (CPM) to measure brain functional connectivity and predict self-reported maternal bonding in mothers at 2 and 8 months postpartum. At 2 months, CPM predicted maternal anxiety in the bonding relationship: Greater integration between cerebellar and motor-sensory-auditory networks and between frontoparietal and motor-sensory-auditory networks were associated with more maternal anxiety toward their infant. Furthermore, greater segregation between the cerebellar and frontoparietal, and within the motor-sensory-auditory networks, was associated with more maternal anxiety regarding their infant. We did not observe CPM prediction of maternal bonding impairments or rejection/anger toward the infant. Finally, considering 2 and 8 months of data, changes in network connectivity were associated with changes in maternal anxiety in the bonding relationship. Our results suggest that changing connectivity among maternal brain networks may provide insight into the mother-infant bond, specifically in the context of anxiety and the representation of the infant in the mother's mind. These findings provide an opportunity to mechanistically investigate approaches to enhance the connectivity of these networks to optimize the representational and behavioral quality of the caregiving relationship.

The Paternal Brain in Action: A Review of Human Fathers' fMRI Brain Responses to Child-Related Stimuli

As fathers are increasingly involved in childcare, understanding the neurological underpinnings of fathering has become a key research issue in developmental psychobiology research. This systematic review specifically focused on (1) highlighting methodological issues of paternal brain research using functional magnetic resonance imaging (fMRI) and (2) summarizing findings related to paternal brain responses to auditory and visual infant stimuli. Sixteen papers were included from 157 retrieved records. Sample characteristics (e.g., fathers’ and infant’s age, number of kids, and time spent caregiving), neuroimaging information (e.g., technique, task, stimuli, and processing), and main findings were synthesized by two independent authors. Most of the reviewed works used different stimuli and tasks to test fathers’ responses to child visual and/or auditory stimuli. Pre-processing and first-level analyses were performed with standard pipelines. Greater heterogeneity emerged in second-level analyses. Three main cortical networks (mentalization, embodied simulation, and emotion regulation) and a subcortical network emerged linked with fathers’ responses to infants’ stimuli, but additional areas (e.g., frontal gyrus, posterior cingulate cortex) were also responsive to infants’ visual or auditory stimuli. This review suggests that a distributed and complex brain network may be involved in facilitating fathers’ sensitivity and responses to infant-related stimuli. Nonetheless, specific methodological caveats, the exploratory nature of large parts of the literature to date, and the presence of heterogeneous tasks and measures also demonstrate that systematic improvements in study designs are needed to further advance the field.

Breastfeeding and maternal attachment during infancy period among Jordanian mothers: A cross-sectional study

Aims

The aim of the current study was to examine the following hypotheses: 1. Mothers who breastfeed their infants from 2 to 12 months of age or who use a mixed-feeding method after birth will demonstrate greater attachment toward their infants than mothers who only formula-feed their infants, as measured by the Maternal Attachment Inventory (MAI). 2. A difference in maternal attachment levels will be observed between mothers who exclusively formula-feed their infants and those who exclusively breastfeed their infants from 2 to 12 months of age, as measured by the MAI inventory, controlling for infant temperament.

Method

A cross-sectional, descriptive, comparative method was applied in different healthcare centers in Jordan from May 2016 to August 2016 in which the MAI inventory was employed to assess 258 Arabic-speaking mothers. One-way analysis of variance was used to detect the differences in maternal attachment between mothers using different feeding methods.

Results

The findings showed significant differences in maternal attachment between exclusive breastfeeding and exclusive formula-feeding mothers, and mixed-feeding mothers at 2 months (F = 24.36, P < .01). Moreover, there was a statistically significant difference in maternal attachment between the breastfeeding and the formula-feeding group (F = 24.358, p < .05) after holding temperament constant.

Conclusion

The results of this current study may help to clarify one role of breastfeeding in shaping a mother's attachment. Healthcare providers need to understand the influences of these variables on maternal attachment and attachment to empower young mothers and counsel them appropriately.

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Poor maternal attachment could lead to insecure infant attachment.

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Healthcare providers need to understand the influences of some factors on maternal attachment.

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Significant difference in maternal attachment between the breastfeeding and the formula-feeding mothers.