Unique salience of maternal breast odors for newborn infants

The influence of olfactory experience on the birthrates of olfactory sensory neurons with specific odorant receptor identities

Olfactory sensory neurons (OSNs) are one of a few neuron types that are generated continuously throughout life in mammals. The persistence of olfactory sensory neurogenesis beyond early development has long been thought to function simply to replace neurons that are lost or damaged through exposure to environmental insults. The possibility that olfactory sensory neurogenesis may also serve an adaptive function has received relatively little consideration, largely due to the assumption that the generation of new OSNs is stochastic with respect to OSN subtype, as defined by the single odorant receptor gene that each neural precursor stochastically chooses for expression out of hundreds of possibilities. Accordingly, the relative birthrates of different OSN subtypes are predicted to be constant and impervious to olfactory experience. This assumption has been called into question, however, by evidence that the birthrates of specific OSN subtypes can be selectively altered by manipulating olfactory experience through olfactory deprivation, enrichment, and conditioning paradigms. Moreover, studies of recovery of the OSN population following injury provide further evidence that olfactory sensory neurogenesis may not be strictly stochastic with respect to subtype. Here we review this evidence and consider mechanistic and functional implications of the prospect that specific olfactory experiences can regulate olfactory sensory neurogenesis rates in a subtype-selective manner.

Testing detectability, attractivity, hedonic specificity, extractability, and robustness of colostrum odor-Toward an olfactory bioassay for human neonates

Human milk odor is attractive and appetitive for human newborns. Here, we studied behavioral and heart-rate (HR) responses of 2-day-old neonates to the odor of human colostrum. To evaluate detection in two conditions of stimulus delivery, we first presented the odor of total colostrum against water. Second, the hedonic specificity of total colostrum odor was tested against vanilla odor. Third, we delivered only the fresh effluvium of colostrum separated from the colostrum matrix; the stability of this colostrum effluvium was then tested after deep congelation; finally, after sorptive extraction of fresh colostrum headspace, we assessed the activity of colostrum volatiles eluting from the gas chromatograph (GC). Regardless of the stimulus-delivery method, neonates displayed attraction reactions (HR decrease) as well as appetitive oral responses to the odor of total colostrum but not to vanilla odor. The effluvium separated from the fresh colostrum matrix remained appetitive but appeared labile under deep freezing. Finally, volatiles from fresh colostrum effluvium remained behaviorally active after GC elution, although at lower magnitude. In sum, fresh colostrum effluvium and its eluate elicited a consistent increase in newborns' oral activity (relative to water or vanilla), and they induced shallow HR decrease. Newborns' appetitive oral behavior was the most reproducible response criterion to the effluvium of colostrum. In conclusion, a set of unidentified volatile compounds from human colostrum is robust enough after extraction from the original matrix and chromatographic processing to continue eliciting appetitive responses in neonates, thus opening new directions to isolate and assay specific volatile molecules of colostrum.

Body odor samples from infants and post-pubertal children differ in their volatile profiles

Body odors change during development, and this change influences the interpersonal communication between parents and their children. The molecular basis for this chemical communication has not been elucidated yet. Here, we show by combining instrumental and sensory analyses that the qualitative odorant composition of body odor samples is similar in infants (0-3 years) and post-pubertal children (14-18 years). The post-pubertal samples are characterized by higher odor dilution factors for carboxylic acids and by the presence of 5α-androst-16-en-3-one and 5α-androst-16-en-3α-ol. In addition to the olfaction-guided approach, the compounds 6-methylhept-5-en-2-one (6MHO), geranyl acetone (GA) and squalene (SQ) were quantified. Both age groups have similar concentrations of 6MHO and GA, whereas post-pubertal children tend to have higher concentration of SQ. In conclusion, sexual maturation coincides with changes to body odor chemical composition. Whether those changes explain differences in parental olfactory perception needs to be determined in future studies with model odors.

Intrinsic and extrinsic factors affecting axillary odor variation. A comprehensive review

Humans produce odorous secretions from multiple body sites according to the microbiomic profile of each area and the types of secretory glands present. Because the axilla is an active, odor-producing region that mediates social communication via the sense of smell, this article focuses on the biological mechanisms underlying the creation of axillary odor, as well as the intrinsic and extrinsic factors likely to impact the odor and determine individual differences. The list of intrinsic factors discussed includes sex, age, ethnicity, emotions, and personality, and extrinsic factors include dietary choices, diseases, climate, and hygienic habits. In addition, we also draw attention to gaps in our understanding of each factor, including, for example, topical areas such as the effect of climate on body odor variation. Fundamental challenges and emerging research opportunities are further outlined in the discussion. Finally, we suggest guidelines and best practices based on the factors reviewed herein for preparatory protocols of sweat collection, data analysis, and interpretation.

Dynamic developmental changes in neurotransmitters supporting infant attachment learning

Infant survival relies on rapid identification, remembering and behavioral responsiveness to caregivers' sensory cues. While neural circuits supporting infant attachment learning have largely remained elusive in children, use of invasive techniques has uncovered some of its features in rodents. During a 10-day sensitive period from birth, newborn rodents associate maternal odors with maternal pleasant or noxious thermo-tactile stimulation, which gives rise to a preference and approach behavior towards these odors, and blockade of avoidance learning. Here we review the neural circuitry supporting this neonatal odor learning, unique compared to adults, focusing specifically on the early roles of neurotransmitters such as glutamate, GABA (Gamma-AminoButyric Acid), serotonin, dopamine and norepinephrine, in the olfactory bulb, the anterior piriform cortex and amygdala. The review highlights the importance of deepening our knowledge of age-specific infant brain neurotransmitters and behavioral functioning that can be translated to improve the well-being of children during typical development and aid in treatment during atypical development in childhood clinical practice, and the care during rearing of domestic animals.

Infant factors that impact the ecology of human milk secretion and composition-a report from "Breastmilk Ecology: Genesis of Infant Nutrition (BEGIN)" Working Group 3

Infants drive many lactation processes and contribute to the changing composition of human milk through multiple mechanisms. This review addresses the major topics of milk removal; chemosensory ecology for the parent-infant dyad; the infant's inputs into the composition of the human milk microbiome; and the impact of disruptions in gestation on the ecology of fetal and infant phenotypes, milk composition, and lactation. Milk removal, which is essential for adequate infant intake and continued milk synthesis through multiple hormonal and autocrine/paracrine mechanisms, should be effective, efficient, and comfortable for both the lactating parent and the infant. All 3 components should be included in the evaluation of milk removal. Breastmilk "bridges" flavor experiences in utero with postweaning foods, and the flavors become familiar and preferred. Infants can detect flavor changes in human milk resulting from parental lifestyle choices, including recreational drug use, and early experiences with the sensory properties of these recreational drugs impact subsequent behavioral responses. Interactions between the infant's own developing microbiome, that of the milk, and the multiple environmental factors that are drivers-both modifiable and nonmodifiable-in the microbial ecology of human milk are explored. Disruptions in gestation, especially preterm birth and fetal growth restriction or excess, impact the milk composition and lactation processes such as the timing of secretory activation, adequacy of milk volume and milk removal, and duration of lactation. Research gaps are identified in each of these areas. To assure a sustained and robust breastfeeding ecology, these myriad infant inputs must be systematically considered.

Pleasant and unpleasant odor identification ability is associated with distinct dimensions of negative symptoms transdiagnostically in psychotic disorders

Negative symptoms are among the greatest sources of functional impairment for individuals with schizophrenia, yet their mechanisms remain poorly understood. Olfactory impairment is associated with negative symptoms. The processing of pleasant olfactory stimuli is subserved by reward-related neural circuitry while unpleasant olfactory processing is subserved by emotion-related neural circuitry, suggesting that these two odor dimensions may offer a window into differential mechanisms of negative symptoms. We examined whether pleasant and unpleasant odor identification bears differential relationships with avolition and inexpressivity dimensions of negative symptoms, whether these relationships are transdiagnostic, and whether pleasant and unpleasant odor processing also relate differently to other domains of functioning in a sample of individuals diagnosed with schizophrenia (N = 54), other psychotic disorders (N = 65), and never-psychotic adults (N = 160). Hierarchical regressions showed that pleasant odor identification was uniquely associated with avolition, while unpleasant odor identification was uniquely associated with inexpressivity. These relationships were largely transdiagnostic across groups. Additionally, pleasant and unpleasant odor identification displayed signs of specificity with other functional and cognitive measures. These results align with past work suggesting dissociable pathomechanisms of negative symptoms and provide a potential avenue for future work using valence-specific olfactory dysfunction as a semi-objective and low-cost marker for understanding and predicting the severity of specific negative symptom profiles.

Non-Pharmacological Management for Vaccine-Related Pain in Children in the Healthcare Setting: A Scoping Review

Purpose

To examine how research was conducted on non-pharmacological management in children with vaccine-related pain in the healthcare setting, so as to provide reference for the relief of vaccine-related pain in children.

Methods

This study conducted a scoping review guided by the methodological framework of Arksey and O’Malley. MEDLINE, Cochrane Library, EMBASE, CINAHL, PubMed databases were searched in detail, and search strategy included the keyword “vaccine”, the keyword “pain”, and the keyword “children”. Two researchers conducted literature screening and data extraction independently, and any disagreements were resolved through team consultation.

Results

This study retrieved 1017 literatures, of which 22 were finally included, including 18 randomized controlled studies, 3 quasi-experimental studies and 1 cohort study. Non-pharmacological management measures were summarized in the study, mainly involving taste, tactile, olfactory, visual, exercise, and postural interventions and injection technique. All the above non-pharmacological management were effective in mitigating vaccine-related pain in children. The study population in the included literatures was mainly neonates and infants. Regarding the analgesic effects of taste intervention, breastfeeding was better than sweeteners, and sweeteners were better than sterile water or non-nutritive sucking. However, there was a lack of comparative studies on the analgesic effects of other non-pharmacological management.

Conclusion

There are many non-pharmacological management measures with varying analgesic effects. Diversified non-pharmacological management measures can provide more analgesic choices for children. For reducing vaccine-related pain in newborns and infants, breastfeeding is recommended first, then sweeteners, and then non-nutritious sucking. In addition to the taste intervention, the analgesic effects of other non-pharmacological management measures need further comparative studies. Moreover, medical staff can use a combination of non-pharmacological analgesic measures to maximize the analgesic effect, and medical staff should also fully consider the analgesia willingness of children and parents.

Humans and the Olfactory Environment: A Case of Gene-Culture Coevolution?

As hunter-gatherers, humans used their sense of smell to identify plants and animals, to find their way within a foraging area, or to distinguish each other by gender, age, kinship, or social dominance. Because women gathered while men hunted, the sexes evolved different sensitivities to plant and animal odors. They also ended up emitting different odors. Male odors served to intimidate rival males or assert dominance. With the rise of farming and sedentism, humans no longer needed their sense of smell to find elusive food sources or to orient themselves within a large area. Odors now came from a narrower range of plants and animals. Meanwhile, body odor was removed through bathing to facilitate interactions in enclosed spaces. This new phenotype became the template for the evolution of a new genotype: less sensitivity to odors of wild plants and animals, lower emissions of male odors, and a more negative response to them. Further change came with the development of fragrances to reodorize the body and the home. This new olfactory environment coevolved with the ability to represent odors in the mind, notably for storage in memory, for vicarious re-experiencing, or for sharing with other people through speech and writing.

The effect of breastfeeding, breast milk odour and mother's heartbeat sound on pain level in newborns: A randomized trial

AIM

This study aimed to compare the effects of breastfeeding, breast milk odour and mother's heartbeat sounds on perceived pain during heel lance procedures in term newborns.

DESIGN

This was a randomized three-group experimental study.

METHODS

The sample of the study consisted of 90 newborns. The data were collected using pulse oximeter, fetal hand doppler, voice recorder, loudspeaker, a data collection form and the ALPS-Neo Pain and Stress Assessment Scale for Newborn Infants.

RESULTS

During the procedure, newborns in the breast milk odour group had high levels of pain and stress, those in the mother's heartbeat sounds group had mild pain and stress, and those in the breastfeeding group had no pain and stress. Additionally, a statistically significant difference was found between their crying times. This difference was the highest for newborns in the breast milk odour group, followed by the mother's heartbeat sounds and breastfeeding groups, respectively.

CONCLUSION

Breastfeeding and mother's heartbeat sounds, which are non-pharmacological pain relief methods, are effective in neonatal pain management. However, breast milk odour is not effective for pain control in newborns. Further studies should examine the efficacy combinations of these methods.

Maternal chemosignals enhance infant-adult brain-to-brain synchrony

Maternal body odors serve as important safety-promoting and social recognition signals, but their role in human brain maturation is largely unknown. Utilizing ecological paradigms and dual- electroencephalography recording, we examined the effects of maternal chemosignals on brain-to-brain synchrony during infant-mother and infant-stranger interactions with and without the presence of maternal body odors. Neural connectivity of right-to-right brain theta synchrony emerged across conditions, sensitizing key nodes of the infant’s social brain during its maturational period. Infant-mother interaction elicited greater brain-to-brain synchrony; however, maternal chemosignals attenuated this difference. Infants exhibited more social attention, positive arousal, and safety/approach behaviors in the maternal chemosignals condition, which augmented infant-stranger neural synchrony. Human mothers use interbrain mechanisms to tune the infant’s social brain, and chemosignals may sustain the transfer of infant sociality from the mother-infant bond to life within social groups.

Olfaction in the Multisensory Processing of Faces: A Narrative Review of the Influence of Human Body Odors

A recent body of research has emerged regarding the interactions between olfaction and other sensory channels to process social information. The current review examines the influence of body odors on face perception, a core component of human social cognition. First, we review studies reporting how body odors interact with the perception of invariant facial information (i.e., identity, sex, attractiveness, trustworthiness, and dominance). Although we mainly focus on the influence of body odors based on axillary odor, we also review findings about specific steroids present in axillary sweat (i.e., androstenone, androstenol, androstadienone, and estratetraenol). We next survey the literature showing body odor influences on the perception of transient face properties, notably in discussing the role of body odors in facilitating or hindering the perception of emotional facial expression, in relation to competing frameworks of emotions. Finally, we discuss the developmental origins of these olfaction-to-vision influences, as an emerging literature indicates that odor cues strongly influence face perception in infants. Body odors with a high social relevance such as the odor emanating from the mother have a widespread influence on various aspects of face perception in infancy, including categorization of faces among other objects, face scanning behavior, or facial expression perception. We conclude by suggesting that the weight of olfaction might be especially strong in infancy, shaping social perception, especially in slow-maturing senses such as vision, and that this early tutoring function of olfaction spans all developmental stages to disambiguate a complex social environment by conveying key information for social interactions until adulthood.

Newborn mice form lasting CA2-dependent memories of their mothers

Some of the most enduring social connections begin when infants first recognize their caregivers, memories that form the basis of many family relationships. It remains unknown whether these early social memories persist into adulthood in mice and, if so, which brain regions support them. Here we show that mice form memories of their mother within days after birth and that these memories persist into adulthood. Pups display greater interest in the mother than in an unfamiliar dam before weaning, after which this preference reverses. Inhibition of CA2 neurons in the pup temporarily blocks the ability to discriminate between the mother and an unfamiliar dam, whereas doing so in adulthood prevents the formation of short-term memories about conspecifics, as well as social discrimination related to long-term memories of the mother. These results suggest that the CA2 supports memories of the mother during infancy and adulthood with a developmental switch in social preference.

Human neonates prefer colostrum to mature milk: Evidence for an olfactory bias toward the "initial milk"?

OBJECTIVES

Colostrum is the initial milk secretion which ingestion by neonates warrants their adaptive start in life. Colostrum is accordingly expected to be attractive to newborns. The present study aims to assess whether colostrum is olfactorily attractive for 2-day-old newborns when presented against mature milk or a control.

METHODS

The head-orientation of waking newborns was videotaped in three experiments pairing the odors of: (a) colostrum (sampled on postpartum day 2, not from own mother) and mature milk (sampled on average on postpartum day 32, not from own mother) (n tested newborns = 15); (b) Colostrum and control (water; n = 9); and (c) Mature milk and control (n = 13).

RESULTS

When facing the odors of colostrum and mature milk, the infants turned their nose significantly longer toward former (32.8 vs 17.7% of a 120-s test). When exposed to colostrum against the control, they responded in favor of colostrum (32.9 vs 16.6%). Finally, when the odor of mature milk was presented against the control, their response appeared undifferentiated (26.7 vs 28.6%).

CONCLUSIONS

These results indicate that human newborns can olfactorily differentiate conspecific lacteal fluids sampled at different lactation stages. They prefer the odor of the mammary secretion - colostrum - collected at the lactation stage that best matches the postpartum age of their own mother. These results are discussed in the context of the earliest mother-infant chemo-communication. Coinciding maternal emission and offspring reception of chemosignals conveyed in colostrum may be part of the sensory precursors of attunement between mothers and infants.

Effect of environmental exposure to a maternally-learned odorant on anxiety-like behaviors at weaning in mice

Early sensory experience, such as exposure to maternal or other environmental factors, is considered to influence neurocognitive development and behaviors. In many species, exposure to odorants during pregnancy or lactation impacts the morpho-functional development of the olfactory circuitry with changes in olfactory sensitivity, feeding behavior and food preferences at birth or later. However, few studies have investigated the impact of a perinatal exposure to odorants on the anxiety-like behavior of animals to stressfull stimuli. Here, we exposed mice to heptaldehyde (HEP) during pregnancy and lactation and measured the anxiety-like behavior of their offspring to stress-inducing novel stimuli at weaning in presence or absence of odorants. We applied a combined social and maternal separation as a stressor and measured the anxiety-like behavior in an open field (OF) in presence of two odorants, HEP or α-pinene (AP) as a control odorant. Although the presence of the odorant during the social separation did not influence anxiety-like behavior, we found that, if mice born to non-odorized mothers exhibited a decreased exploratory behavior in the presence of both odorants, the effect was restricted to AP for the mice perinatally exposed to HEP. These results show that anxiety-like behaviors during a stress-inducing event could be reduced by the presence of a familiar odorant. We propose that the recall of an early olfactory experience could contribute to the improvement of animal welfare in various situations associated with husbandry practices.

Design, delivery and perception of condition-dependent chemical signals in strepsirrhine primates: implications for human olfactory communication

The study of human chemical communication benefits from comparative perspectives that relate humans, conceptually and empirically, to other primates. All major primate groups rely on intraspecific chemosignals, but strepsirrhines present the greatest diversity and specialization, providing a rich framework for examining design, delivery and perception. Strepsirrhines actively scent mark, possess a functional vomeronasal organ, investigate scents via olfactory and gustatory means, and are exquisitely sensitive to chemically encoded messages. Variation in delivery, scent mixing and multimodality alters signal detection, longevity and intended audience. Based on an integrative, 19-species review, the main scent source used (excretory versus glandular) differentiates nocturnal from diurnal or cathemeral species, reflecting differing socioecological demands and evolutionary trajectories. Condition-dependent signals reflect immutable (species, sex, identity, genetic diversity, immunity and kinship) and transient (health, social status, reproductive state and breeding history) traits, consistent with socio-reproductive functions. Sex reversals in glandular elaboration, marking rates or chemical richness in female-dominant species implicate sexual selection of olfactory ornaments in both sexes. Whereas some compounds may be endogenously produced and modified (e.g. via hormones), microbial analyses of different odorants support the fermentation hypothesis of bacterial contribution. The intimate contexts of information transfer and varied functions provide important parallels applicable to olfactory communication in humans. This article is part of the Theo Murphy meeting issue 'Olfactory communication in humans'.

Human olfactory communication: current challenges and future prospects

Although anthropologists frequently report the centrality of odours in the daily lives and cultural beliefs of many small-scale communities, Western scholars have historically considered the sense of smell as minimally involved in human communication. Here, we suggest that the origin and persistence of this latter view might be a consequence of the fact that most research is conducted on participants from Western societies who, collectively, were rather old (adults), deodorized and desensitized (ODD) to various aspects of olfactory perception. The view is rapidly changing, however, and this themed issue provides a timely overview of the current state-of-the-art on human chemocommunication. Based on evolutionary models of communication, the papers cover both general mechanisms of odour production by 'senders' and odour perception by 'receivers'. Focus on specific functional contexts includes reciprocal impact of odours between infants and mothers, the role of odour in mate choice and how odours communicate emotion and disease. Finally, a position paper outlines pitfalls and opportunities for the future, against the context of the replication crisis in psychology. We believe a more nuanced view of human chemical communication is within our grasp if we can continue to develop inter-disciplinary insights and expand research activities beyond ODD people. This article is part of the Theo Murphy meeting issue 'Olfactory communication in humans'.

A plausible pathway of imprinted behaviors: Skin-to-skin actions of the newborn immediately after birth follow the order of fetal development and intrauterine training of movements

We hypothesize that the competence of a newborn in the first hours after birth is the direct result of behavior training that begins during the first 12 weeks of fetal life. Correlation of Widström's 9 Instinctive Stages (behaviors of the full-term newborn during the first hours after birth) with the developmental movements during fetal life demonstrate that the fetus is invested in learning specific tasks, in a specific order, that are evolutionarily necessary for survival during the first hour and beyond.

Individual Differences as a Key Factor to Uncover the Neural Underpinnings of Hedonic and Social Functions of Human Olfaction: Current Findings from PET and fMRI Studies and Future Considerations

The hedonic and social dimensions of olfactory perception are characterized by a great diversity across people. Whereas the cerebral processing underlying these aspects of odor perception have been widely explored in the last decades, very few brain imaging studies considered individual differences. This lack of consideration weakens the current models in the field, where the paradigm of universality is the norm. The present review is aimed at examining this issue. Through a synthetic summary, we will first present past studies suggesting that (1) hedonics are represented consistently throughout the olfactory system from primary to secondary areas, with a progressive cognitive modulation and integration with other senses, (2) social dimension of odors may be represented in a distinct pathway involving social and attentional networks. In a second, and more critical part, we will highlight the importance of individual differences for the cerebral study of human olfaction.

Feeding circuit development and early-life influences on future feeding behaviour

A wide range of maternal exposures - undernutrition, obesity, diabetes, stress and infection - are associated with an increased risk of metabolic disease in offspring. Developmental influences can cause persistent structural changes in hypothalamic circuits regulating food intake in the service of energy balance. The physiological relevance of these alterations has been called into question because maternal impacts on daily caloric intake do not persist to adulthood. Recent behavioural and epidemiological studies in humans provide evidence that the relative contribution of appetitive traits related to satiety, reward and the emotional aspects of food intake regulation changes across the lifespan. This Opinion article outlines a neurodevelopmental framework to explore the possibility that crosstalk between developing circuits regulating different modalities of food intake shapes future behavioural responses to environmental challenges.

Body-odor based assessments of sex and personality - Non-significant differences between blind and sighted odor raters

People exhibit different sensitivity to the signaling properties of body odors in the social context. Here, we aimed to investigate whether visual status modulates sensitivity to socially-relevant cues carried by body odors and whether it affects psychophysical ratings of such smells. We compared abilities of 19 early-blind, 9 late-blind and 13 sighted people to accurately assess sex, neuroticism and dominance of odor donors based on body odor samples. We showed that early blind, late blind and sighted people do not differ in accuracy of sex and personality assessments based on body odor samples. Additionally, the three participating groups perceived the presented body odor samples as similarly intense, pleasant and attractive. We discuss our findings in the context of interpersonal olfactory communication and olfactory compensation.

Birth practices: Maternal-neonate separation as a source of toxic stress

Maternal-neonate separation for human newborns has been the standard of care since the last century; low birth weight and preterm infants are still routinely separated from their mothers. With advanced technology, survival is good, but long-term developmental outcomes are very poor for these especially vulnerable newborns. The poor outcomes are similar to those described for adversity in childhood, ascribed to toxic stress. Toxic stress is defined as the absence of the buffering protection of adult support. Parental absence has been strictly enforced in neonatal care units for many reasons and could lead to toxic stress. The understanding of toxic stress comes from discoveries about our genome and epigenetics, the microbiome, developmental neuroscience and the brain connectome, and life history theory. The common factor is the early environment that gives (a) signals to epigenes, (b) sensory inputs to neural circuits, and (c) experiences for reproductive fitness. For human newborns that environment is direct skin-to-skin contact from birth. Highly conserved neuroendocrine behaviors determined by environment are described in this review. The scientific rationale underlying skin-to-skin contact is presented: autonomic development and regulation of the physiology leads to emotional connection and achieving resilience. Maternal-neonate separation prevents these critical neural processes from taking place, but also channel development into an alternative developmental strategy. This enables better coping in a stressful environment in the short term, but with permanently elevated stress systems that negatively impact mental and physical health in the long term. This may explain the increasing incidence of developmental problems in childhood, and also Developmental Origins of Health and Disease. Arguments are presented that maternal-neonate separation is indeed a source of toxic stress, and some suggestions are offered toward a "zero separation" paradigm.

A Review of Non-Pharmacological Treatments for Pain Management in Newborn Infants

Pain is a major problem in sick newborn infants, especially for those needing intensive care. Pharmacological pain relief is the most commonly used, but might be ineffective and has side effects, including long-term neurodevelopmental sequelae. The effectiveness and safety of alternative analgesic methods are ambiguous. The objective was to review the effectiveness and safety of non-pharmacological methods of pain relief in newborn infants and to identify those that are the most effective. PubMed and Google Scholar were searched using the terms: “infant”, “premature”, “pain”, “acupuncture”, “skin-to-skin contact”, “sucrose”, “massage”, “musical therapy” and ‘breastfeeding’. We included 24 studies assessing different methods of non-pharmacological analgesic techniques. Most resulted in some degree of analgesia but many were ineffective and some were even detrimental. Sucrose, for example, was often ineffective but was more effective than music therapy, massage, breast milk (for extremely premature infants) or non-invasive electrical stimulation acupuncture. There were also conflicting results for acupuncture, skin-to-skin care and musical therapy. Most non-pharmacological methods of analgesia provide a modicum of relief for preterm infants, but none are completely effective and there is no clearly superior method. Study is also required to assess potential long-term consequences of any of these methods.

Maternal areola pH: A chemical basis for mother-infant recognition

BACKGROUND

The human female's areolar region is the point of arrival of a natural progression from birth to breastfeeding continuum, supported by numerous functional features.

AIMS

The aim of this study was to look more closely into the areola' skin chemical signals that are uniquely important for mother-infant chemoemission, chemoreception, and breastfeeding continuum.

STUDY DESIGN

A dermatological study of the areolae and corresponding breast quadrants was undertaken on 71 healthy, at-term women. Areolar and corresponding breast quadrant pH were assessed pre-partum and 1 and 2 days post-partum using a corneometer (Soft Plus 5.5; Callegari S.P.A., Parma, Italy).

RESULTS

Pre-partum, the pH of the areola was significantly higher than the pH of the breast quadrant (4.25 ± 0.26 vs. 4.06 ± 0.44, p < 0.015). Post-partum, the pH of the areola was significantly higher that the pH of the breast quadrant both on day one (4.28 ± 0.31 vs 4.01 ± 0.25, p < 0.001) and on day two (4.39 ± 0.19 vs 4.01 ± 0.16, p < 0.001), respectively. In addition, pre-labor pH of the areola increased on day one post-partum and significantly on day two postpartum (4.25 ± 0.26 vs 4.39 ± 0.19, p 0.004). Moreover, the pH of the areola increased significantly from day one to day two post-partum (4.28 ± 0.31 v s 4.39 ± 0.19, p < 0.041).

CONCLUSIONS

Our findings show, for the first time, that the areola has a higher pH than the surrounding breast skin, and this increases from day one to day two postpartum. We believe that the pH changes of the areolar region may act as a unique chemical signal to guide the infant directly to the nipple.

The Analgesic Effects of Maternal Milk Odor on Newborns: A Meta-Analysis

OBJECTIVE

The objective of this study was to evaluate the analgesic effects of maternal milk odor on newborns.

MATERIALS AND METHODS

We searched the literature in PubMed, MEDLINE, CINAHL, EMBASE, Web of Science, and the Cochrane Central Register of Controlled Trials (CENTRAL) and collected all the randomized controlled trials (RCTs) investigating the effects of maternal milk odor versus scentless or other odors on procedural pain in newborns. The quality of included studies was assessed by the Cochrane Collaboration Risk of Bias tool. A meta-analysis was undertaken with the Review Manager 5.3 software and Stata version 11.0. Subgroup comparisons were prespecified according to the types of control groups.

RESULTS

Eight RCTs included a total of 453 participants. The results of meta-analysis showed that compared with the scentless group, the maternal milk odor group had lower pain scores during blood sampling (standardized mean difference, -0.81; 95% confidence interval [95% CI], -1.18 to -0.44; p < 0.001) and shorter crying time afterward (mean difference, -8.10; 95% CI, -15.46 to 0.73; p = 0.03). The maternal milk odor group had lower heart rate variability and oxygen saturation variability during and after a procedure, compared with both the scentless group and the vanilla group. However, no significant difference was identified in the mean heart rate and mean oxygen saturation in terms of the maternal milk odor group compared with amniotic fluid odor or mother's scent. The maternal milk odor group versus the formula milk odor group had shorter crying duration and lower levels of salivary cortisol after sampling.

CONCLUSIONS

Maternal milk odor appears to play an analgesic role in newborns. However, more high-quality studies are needed to confirm and quantitate the effect.

Neonatal Transitions in Social Behavior and Their Implications for Autism

Within the context of early infant-caregiver interaction, we review a series of pivotal transitions that occur within the first 6 months of typical infancy, with emphasis on behavior and brain mechanisms involved in preferential orientation towards, and interaction with, other people. Our goal in reviewing these transitions is to better understand how they may lay a necessary and/or sufficient groundwork for subsequent phases of development, and also to understand how the breakdown thereof, when development is atypical and those transitions become derailed, may instead yield disability. We review these developmental processes in light of recent studies documenting disruptions to early-emerging brain and behavior mechanisms in infants later diagnosed with autism spectrum disorder, shedding light on the brain-behavior pathogenesis of autism.

An implementation algorithm to improve skin-to-skin practice in the first hour after birth

Evidence supporting the practice of skin‐to‐skin contact and breastfeeding soon after birth points to physiologic, social, and psychological benefits for both mother and baby. The 2009 revision of Step 4 of the WHO/UNICEF “Ten Steps to Successful Breastfeeding” elaborated on the practice of skin‐to‐skin contact between the mother and her newly born baby indicating that the practice should be “immediate” and “without separation” unless documented medically justifiable reasons for delayed contact or interruption exist. While in immediate, continuous, uninterrupted skin‐to‐skin contact with mother in the first hour after birth, babies progress through 9 instinctive, complex, distinct, and observable stages including self‐attachment and suckling. However, the most recent Cochrane review of early skin‐to‐skin contact cites inconsistencies in the practice; the authors found “inadequate evidence with respect to details … such as timing of initiation and dose.” This paper introduces a novel algorithm to analyse the practice of skin to skin in the first hour using two data sets and suggests opportunities for practice improvement. The algorithm considers the mother's Robson criteria, skin‐to‐skin experience, and Widström's 9 Stages. Using data from vaginal births in Japan and caesarean births in Australia, the algorithm utilizes data in a new way to highlight challenges to best practice. The use of a tool to analyse the implementation of skin‐to‐skin care in the first hour after birth illuminates the successes, barriers, and opportunities for improvement to achieving the standard of care for babies. Future application should involve more diverse facilities and Robson's classifications.

On the Communicative Function of Body Odors

Humans use multiple senses to navigate the social world, and the sense of smell is arguably the most underestimated one. An intriguing aspect of the sense of smell is its social communicative function. Research has shown that human odors convey information about a range of states (e.g., emotions, sickness) and traits (e.g., individuality, gender). Yet, what underlies the communicability of these states and traits via smell? We fill this explanatory gap with a framework that highlights the dynamic and flexible aspects of human olfactory communication. In particular, we explain how chemical profiles, associative learning (i.e., the systematic co-occurrence of chemical profiles with state- or trait-related information), and top-down contextual influences could interact to shape human odor perception. Our model not only helps to integrate past research on human olfactory communication but it also opens new avenues for future research on this fascinating, yet to date poorly understood, field.

A temperature gradient may support mother-infant thermal identification and communication in the breast crawl from birth to breastfeeding

AIM

The human female's nipple-areolar complex (NAC) is the point of arrival of a natural progression from birth to breastfeeding, linked to functional, chemical and biophysical cues that promote the breast crawl soon after birth. We investigated the thermal gradient generated by the lips of the neonate and warmth of the NAC, which may drive the infant directly to the nipple.

METHODS

We prospectively studied 41 full-term singleton infants and their mothers at the Policlinico Abano Terme, Italy, between January 1, 2015, and February 28, 2015. NAC and breast quadrant temperatures were assessed 6 ± 2 hours prepartum and one and two days postpartum, together with the neonates' lip temperature.

RESULTS

The temperature of the neonates' lips was significantly lower than the forehead temperature on days one and two postpartum (delta = -1.24°C, p < 0.001 and delta = -1.02°C, p < 0.001, respectively). Thus, the thermal gradient between the NAC and the neonates' lips was -1.66 ± 1.07°C on day one (p < 0.001) and -1.68 ± 0.63°C (p < 0.001) on day two postpartum.

CONCLUSION

These findings demonstrate, for the first time, that a temperature gradient may support mother-infant thermal identification and communication in the breast crawl and in the natural progression of the continuum from birth to breastfeeding.

Chemical Identification of "Maternal Signature Odors" in Rat

Newborn altricial mammals need just after birth to locate their mother's nipples for suckling. In this precocious behavior, including for the human baby, maternal odor via the olfactory process plays a major role. Maternal odor emitted by lactating females or by amniotic fluid (AF) attracts pups, but the chemical identity of this attractant has not yet been elucidated. Here, using behavioral tests and gas chromatography coupled with mass spectrometry (GC-MS) techniques, we show that AF extracts from rat pregnant female, nipples, ventral skin, milk, and nest extracts of mother contained 3-6 active substances. AF extracts contained 3 active compounds: ethylbenzene, benzaldehyde, and benzyl alcohol, and their mixture in similar proportions to those found in AF extracts, in a ratio, respectively, of 1:1:12 (700 ng), attracts pups as putative maternal attractant substances (MAS). These 3 AF substances have already been identified in milk, nipples, ventral wash, and nest extracts of mother, but not in feces. Moreover, anethole flavor incorporated in pregnant rat and mother's diet is also detected in AF, nipples, milk, and nest extracts and the pups are attracted to anethole odor, but not in the case of the no-anethole pups. MAS, combined with diet flavors present in the AF bath, represent olfactory signals as "maternal signature odors" (MSO) that are learned by fetus and pups. These findings open the way to improved understanding of the neurobiology of early olfactory learning and of the importance of evolutionarily conserved survival behavior in many mammal species.

Effects of Having Preterm Infants Smell Amniotic Fluid, Mother's Milk, and Mother's Odor During Heel Stick Procedure on Pain, Physiological Parameters, and Crying Duration

OBJECTIVE

The study aims to assess effects of having preterm infants smell amniotic fluid, mother's milk, and mother's odor during heel stick procedure on pain, physiological parameters, and crying duration.

MATERIALS AND METHODS

The study was a randomized controlled experimental research. The population of the study was made up of preterm infants receiving treatment and care at a neonatal intensive care unit, where the study was conducted between January 2015 and March 2016. The study was performed with 85 preterm infants who met the selection criteria. Infants were randomized into four groups: amniotic fluid, mother's milk, mother's odor, and control group. Data obtained were analyzed by percentage distributions, means, standard deviation, chi-square test, Kruskal-Wallis, and Dunnett's test.

RESULTS

While no significant difference was found between the groups in terms of total preterm infant pain profile score before, during, and after the heel stick procedure (p > 0.05), a significant difference was found in terms of SO₂ values (p < 0.05) and the difference was caused by the amniotic fluid group. Although no significant difference was found between the groups in terms of crying duration (p > 0.05), the amniotic fluid group had the lowest score, followed by the mother's milk group, the mother's odor group, and the control group.

CONCLUSIONS

Amniotic fluid, mother's milk, and mother's odor were not effective in preterm infants during painful procedures.

Early skin-to-skin contact for mothers and their healthy newborn infants

BACKGROUND

Mother-infant separation post birth is common. In standard hospital care, newborn infants are held wrapped or dressed in their mother's arms, placed in open cribs or under radiant warmers. Skin-to-skin contact (SSC) begins ideally at birth and should last continually until the end of the first breastfeeding. SSC involves placing the dried, naked baby prone on the mother's bare chest, often covered with a warm blanket. According to mammalian neuroscience, the intimate contact inherent in this place (habitat) evokes neuro-behaviors ensuring fulfillment of basic biological needs. This time frame immediately post birth may represent a 'sensitive period' for programming future physiology and behavior.

OBJECTIVES

To assess the effects of immediate or early SSC for healthy newborn infants compared to standard contact on establishment and maintenance of breastfeeding and infant physiology.

SEARCH METHODS

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (17 December 2015), made personal contact with trialists, consulted the bibliography on kangaroo mother care (KMC) maintained by Dr Susan Ludington, and reviewed reference lists of retrieved studies.

SELECTION CRITERIA

Randomized controlled trials that compared immediate or early SSC with usual hospital care.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed trials for inclusion and risk of bias, extracted data and checked them for accuracy. Quality of the evidence was assessed using the GRADE approach.

MAIN RESULTS

We included 46 trials with 3850 women and their infants; 38 trials with 3472 women and infants contributed data to our analyses. Trials took place in 21 countries, and most recruited small samples (just 12 trials randomized more than 100 women). Eight trials included women who had SSC after cesarean birth. All infants recruited to trials were healthy, and the majority were full term. Six trials studied late preterm infants (greater than 35 weeks' gestation). No included trial met all criteria for good quality with respect to methodology and reporting; no trial was successfully blinded, and all analyses were imprecise due to small sample size. Many analyses had statistical heterogeneity due to considerable differences between SSC and standard care control groups. Results for womenSSC women were more likely than women with standard contact to be breastfeeding at one to four months post birth, though there was some uncertainty in this estimate due to risks of bias in included trials (average risk ratio (RR) 1.24, 95% confidence interval (CI) 1.07 to 1.43; participants = 887; studies = 14; I² = 41%; GRADE: moderate quality). SSC women also breast fed their infants longer, though data were limited (mean difference (MD) 64 days, 95% CI 37.96 to 89.50; participants = 264; studies = six; GRADE:low quality); this result was from a sensitivity analysis excluding one trial contributing all of the heterogeneity in the primary analysis. SSC women were probably more likely to exclusively breast feed from hospital discharge to one month post birth and from six weeks to six months post birth, though both analyses had substantial heterogeneity (from discharge average RR 1.30, 95% CI 1.12 to 1.49; participants = 711; studies = six; I² = 44%; GRADE: moderate quality; from six weeks average RR 1.50, 95% CI 1.18 to 1.90; participants = 640; studies = seven; I² = 62%; GRADE: moderate quality).Women in the SCC group had higher mean scores for breastfeeding effectiveness, with moderate heterogeneity (IBFAT (Infant Breastfeeding Assessment Tool) score MD 2.28, 95% CI 1.41 to 3.15; participants = 384; studies = four; I² = 41%). SSC infants were more likely to breast feed successfully during their first feed, with high heterogeneity (average RR 1.32, 95% CI 1.04 to 1.67; participants = 575; studies = five; I² = 85%). Results for infantsSSC infants had higher SCRIP (stability of the cardio-respiratory system) scores overall, suggesting better stabilization on three physiological parameters. However, there were few infants, and the clinical significance of the test was unclear because trialists reported averages of multiple time points (standardized mean difference (SMD) 1.24, 95% CI 0.76 to 1.72; participants = 81; studies = two; GRADE low quality). SSC infants had higher blood glucose levels (MD 10.49, 95% CI 8.39 to 12.59; participants = 144; studies = three; GRADE: low quality), but similar temperature to infants in standard care (MD 0.30 degree Celcius (°C) 95% CI 0.13 °C to 0.47 °C; participants = 558; studies = six; I² = 88%; GRADE: low quality). Women and infants after cesarean birthWomen practicing SSC after cesarean birth were probably more likely to breast feed one to four months post birth and to breast feed successfully (IBFAT score), but analyses were based on just two trials and few women. Evidence was insufficient to determine whether SSC could improve breastfeeding at other times after cesarean. Single trials contributed to infant respiratory rate, maternal pain and maternal state anxiety with no power to detect group differences. SubgroupsWe found no differences for any outcome when we compared times of initiation (immediate less than 10 minutes post birth versus early 10 minutes or more post birth) or lengths of contact time (60 minutes or less contact versus more than 60 minutes contact).

AUTHORS' CONCLUSIONS

Evidence supports the use of SSC to promote breastfeeding. Studies with larger sample sizes are necessary to confirm physiological benefit for infants during transition to extra-uterine life and to establish possible dose-response effects and optimal initiation time. Methodological quality of trials remains problematic, and small trials reporting different outcomes with different scales and limited data limit our confidence in the benefits of SSC for infants. Our review included only healthy infants, which limits the range of physiological parameters observed and makes their interpretation difficult.

Efficacy of early skin-to-skin contact on the rate of exclusive breastfeeding in term neonates: a randomized controlled trial

BACKGROUND

Despite multiple benefits of breast milk, the rates of exclusive breastfeeding in developing countries are low.

OBJECTIVE

To evaluate the efficacy of early skin -to -skin contact (SSC) on the rate of exclusive breastfeeding (EBF) at 6 weeks of age among term neonates born by vaginal delivery.

METHODS

Term neonates born by vaginal delivery and did not require any resuscitation were randomized at birth to SSC (n=100) and control (n=100) group. Immediately after clamping the umbilical cord, SSC group neonates were placed on the bare bosom of mother and control group neonates were placed under a radiant warmer for a period of 45 minutes each while mothers underwent management of the third stage of labor and episiotomy repair. Pain experienced by mother during episiotomy repair was recorded using a numerical pain scale The primary outcome evaluated was the rate of exclusive breastfeeding at 6 weeks of postnatal age.

RESULTS

A significantly higher proportion of neonates were exclusively breastfeed at 6 weeks of age in the SSC group than in the control group (72% vs. 57.6%, p=0.04, relative risk: 1.3, 95% confidence interval: 1.0 -1.6). The pain score during episiotomy repair in mothers of the SSC group was significantly lower than the control group (4.74±0.85 versus 5.34±0.81; P <0.01).

CONCLUSIONS

Early SSC significantly improved the rate of exclusively breastfeeding at 6 weeks of age among healthy term neonates. An important additional effect was a decrease in the amount of pain that mothers in the SSC group experienced during episiotomy repair.

The higher temperature in the areola supports the natural progression of the birth to breastfeeding continuum

Numerous functional features that promote the natural progression of the birth to breastfeeding continuum are concentrated in the human female's areolar region. The aim of this study was to look more closely into the thermal characteristics of areola, which are said to regulate the local evaporation rate of odors and chemical signals that are uniquely important for the neonate's 'breast crawl'. A dermatological study of the areolae and corresponding intern breast quadrants was undertaken on the mothers of 70 consecutive, healthy, full-term breastfed infants. The study took place just after the births at the Policlinico Abano Terme, in Italy from January to February 2014. Temperature, pH and elasticity were assessed one day postpartum using the Soft Plus 5.5 (Callegari S.P.A., Parma, Italy). The mean areolar temperature was found to be significantly higher than the corresponding breast quadrant (34.60 ±1.40°C vs. 34.04 ±2.00°C, p<0.001) and the pH was also significantly higher (4.60±0.59 vs. 4.17±0.59, p<0.001). In contrast, the elasticity of the areolar was significantly lower (23.52±7.83 vs. 29.02±8.44%, p<0.003). Our findings show, for the first time, that the areolar region has a higher temperature than the surrounding breast skin, together with higher pH values and lower elasticity. We believe that the higher temperature of the areolar region may act as a thermal signal to guide the infant directly to the nipple and to the natural progression of the birth to breastfeeding continuum.

Two-day-old newborn infants recognise their mother by her axillary odour

AIM

The aim of this study was to verify the influence of mother to child skin-to-skin contact and the ability of 2-day-old infants to recognise their own mother's axillary odour.

METHODS

We tested the responses of 19 vaginally delivered, breastfeeding newborns to their mothers' axillary odours using a paired-choice test. The eight males and 11 females were exposed to their own mother's axillary odour and the odour of another unfamiliar new mother taking part in the study, and their responses to each woman were taped for 60 sec. We did this by assessing how long their heads were orientated towards pads carrying the scents of their mothers and the unfamiliar women.

RESULTS

The average time that the infants' heads were orientated towards the olfactory stimulus of their own mothers was 20.53 sec, which was significantly longer than the 11.13 sec recorded for the unfamiliar women (p < 0.05). In addition, this orientation increased significantly with the newborn infants' age in hours (Spearman's Rho = 0.58, p < 0.01) and their recognition time significantly decreased (Spearman's Rho = -0.52, p < 0.05).

CONCLUSION

Two-day-old breastfeeding newborn infants who experienced skin-to-skin contact with their mothers were able to recognise their axillary odour.

Always follow your nose: the functional significance of social chemosignals in human reproduction and survival

This article is part of a Special Issue "Chemosignals and Reproduction" Across phyla, chemosensory communication is crucial for mediating a variety of social behaviors, which form the basis for ontogenetic and phylogenetic survival. In the present paper, evidence on chemosensory communication in humans, with special reference to reproduction and survival, will be presented. First, the impact of chemosignals on human reproduction will be reviewed. Work will be presented, showing how chemosensory signals are involved in mate choice and partnership formation by communicating attractiveness and facilitating a partner selection, which is of evolutionary advantage, and furthermore providing information about the level of sexual hormones. In addition to direct effects on phylogenetic survival, chemosignals indirectly aid reproductive success by fostering harm protection. Results will be presented, showing that chemosensory communication aids the emotional bond between mother and child, which in turn motivates parental caretaking and protection, leading to infant survival. Moreover, the likelihood of group survival can be increased through the use of stress-related chemosignals. Stress-related chemosignals induce a stress-related physiology in the perceiver, thereby priming a fight-flight-response, which is necessary for an optimum adaption to environmental harm. Finally, effects of sexual orientation on chemosensory communication will be discussed in terms of their putative role in stabilizing social groups, which might indirectly provide harm protection and foster survival. An integrative model of the presented data will be introduced. In conclusion, an outlook, focusing on the involvement of chemosensory communication in human social behavior and illustrating a novel approach to the significance of chemosensory signals in human survival, will be given.

Neuroendocrinology of childbirth and mother-child attachment: the basis of an etiopathogenic model of perinatal neurobiological disorders

This review focuses on the neuroendocrine mechanisms in the mother and the newborn that are involved in the generation and consolidation of mother-child attachment. The role that different hormones and neurotransmitters play on the regulation of these mechanisms during parturition, the immediate postpartum period and lactation is discussed. Interferences in the initiation of mother-child attachment may have potential long-term effects for the behavior and affection of the newborn. Therefore, the possible consequences of alterations in the physiological neuroendocrine mechanisms of attachment, caused by elective Cesarean section, intrapartum hormonal manipulations, preterm delivery, mother-infant postpartum separation and bottle-feeding instead of breastfeeding are also discussed.

Development of thalamocortical connectivity during infancy and its cognitive correlations

Although commonly viewed as a sensory information relay center, the thalamus has been increasingly recognized as an essential node in various higher-order cognitive circuits, and the underlying thalamocortical interaction mechanism has attracted increasing scientific interest. However, the development of thalamocortical connections and how such development relates to cognitive processes during the earliest stages of life remain largely unknown. Leveraging a large human pediatric sample (N = 143) with longitudinal resting-state fMRI scans and cognitive data collected during the first 2 years of life, we aimed to characterize the age-dependent development of thalamocortical connectivity patterns by examining the functional relationship between the thalamus and nine cortical functional networks and determine the correlation between thalamocortical connectivity and cognitive performance at ages 1 and 2 years. Our results revealed that the thalamus-sensorimotor and thalamus-salience connectivity networks were already present in neonates, whereas the thalamus-medial visual and thalamus-default mode network connectivity emerged later, at 1 year of age. More importantly, brain-behavior analyses based on the Mullen Early Learning Composite Score and visual-spatial working memory performance measured at 1 and 2 years of age highlighted significant correlations with the thalamus-salience network connectivity. These results provide new insights into the understudied early functional brain development process and shed light on the behavioral importance of the emerging thalamocortical connectivity during infancy.

Quality-space theory in olfaction

Quality-space theory (QST) explains the nature of the mental qualities distinctive of perceptual states by appeal to their role in perceiving. QST is typically described in terms of the mental qualities that pertain to color. Here we apply QST to the olfactory modalities. Olfaction is in various respects more complex than vision, and so provides a useful test case for QST. To determine whether QST can deal with the challenges olfaction presents, we show how a quality space (QS) could be constructed relying on olfactory perceptible properties and the olfactory mental qualities then defined by appeal to that QS of olfactory perceptible properties. We also consider how to delimit the olfactory QS from other modalities. We further apply QST to the role that experience plays in refining our olfactory discriminative abilities and the occurrence of olfactory mental qualities in non-conscious olfactory states. QST is shown to be fully applicable to and useful for understanding the complex domain of olfaction.

Neurobiology of secure infant attachment and attachment despite adversity: a mouse model

Attachment to an abusive caregiver has wide phylogenetic representation, suggesting that animal models are useful in understanding the neural basis underlying this phenomenon and subsequent behavioral outcomes. We previously developed a rat model, in which we use classical conditioning to parallel learning processes evoked during secure attachment (odor-stroke, with stroke mimicking tactile stimulation from the caregiver) or attachment despite adversity (odor-shock, with shock mimicking maltreatment). Here we extend this model to mice. We conditioned infant mice (postnatal day (PN) 7-9 or 13-14) with presentations of peppermint odor and either stroking or shock. We used (14) C 2-deoxyglucose (2-DG) to assess olfactory bulb and amygdala metabolic changes following learning. PN7-9 mice learned to prefer an odor following either odor-stroke or shock conditioning, whereas odor-shock conditioning at PN13-14 resulted in aversion/fear learning. 2-DG data indicated enhanced bulbar activity in PN7-9 preference learning, whereas significant amygdala activity was present following aversion learning at PN13-14. Overall, the mouse results parallel behavioral and neural results in the rat model of attachment, and provide the foundation for the use of transgenic and knockout models to assess the impact of both genetic (biological vulnerabilities) and environmental factors (abusive) on attachment-related behaviors and behavioral development.

Neonatal stomach volume and physiology suggest feeding at 1-h intervals

There is insufficient evidence on optimal neonatal feeding intervals, with a wide range of practices. The stomach capacity could determine feeding frequency. A literature search was conducted for studies reporting volumes or dimensions of stomach capacity before or after birth. Six articles were found, suggesting a stomach capacity of 20 mL at birth.

CONCLUSION

A stomach capacity of 20 mL translates to a feeding interval of approximately 1 h for a term neonate. This corresponds to the gastric emptying time for human milk, as well as the normal neonatal sleep cycle. Larger feeding volumes at longer intervals may therefore be stressful and the cause of spitting up, reflux and hypoglycaemia. Outcomes for low birthweight infants could possibly be improved if stress from overfeeding was avoided while supporting the development of normal gastrointestinal physiology. Cycles between feeding and sleeping at 1-h intervals likely meet the evolutionary expectations of human neonates.

Amniotic fluid or its fatty acids produce actions similar to diazepam on lateral septal neurons firing rate

Human amniotic fluid (AF) contains eight fatty acids (FATs), and both produce anxiolytic-like effects in adult rats and appetitive responses in human newborns. The medial amygdala and lateral septal nucleus function are related to social behavior, but the action of AF or its FATs in this circuit is known. We obtained 267 single-unit extracellular recordings in Wistar rats treated with vehicle (1 mL, s.c.; n = 12), human AF (1 mL, s.c.; n = 12), a FAT mixture (1 mL, s.c.; n = 13), diazepam (1 mg/kg, i.p.; n = 11), and fluoxetine (1 mg/kg, p.o.; n = 12). Compared with the vehicle group, the spontaneous septal firing rate in the AF, FAT mixture, and diazepam groups was the lowest and in the fluoxetine group the highest. Cumulative peristimulus histograms indicated that the significant change in septal firing occurred only in the AF and FAT mixture groups and exclusively in those neurons that increased their firing rate during amygdala stimulation. We conclude that human AF and its FATs produce actions comparable to anxiolytic drugs and are able to modify the responsivity of a circuit involved in social behavior, suggesting facilitation of social recognition processes by maternal-fetal fluids.

Impact and feasibility of breast crawl in a tertiary care hospital

OBJECTIVE

To determine the impact of breast crawl on breast feeding and its feasibility and acceptability in a busy labor room.

STUDY DESIGN

A prospective, single blinded, randomized controlled clinical trial. Impact of breast crawl was studied in one group and the outcome was compared with the other group where breast crawl was not performed. Feasibility and acceptability was determined by analysis of questionnaire given to obstetricians and nurses. Descriptive statistics and χ(2)-analysis was applied to evaluate the questionnaire and to compare the outcome in the two groups.

RESULT

Breast crawl had a significant positive impact on the onset of lactation (P=0.0005) as well as extent of neonatal weight loss on day 3 (0.032).

CONCLUSION

Our study adds to the body of evidence that breast crawl results in positive short-term breast feeding outcome but acceptability of breast crawl as a routine in a busy labor room remains a major issue.

Influence of Skin-to-Skin Contact and Rooming-In on Early Mother–Infant Interaction

The objective of this research was to study influence of birth routines on mother–infant interaction at Day 4. The present research is part of a longitudinal study where mother–infant pairs were randomized by infant location and apparel. We intended to assess mother–infant interaction from videos filmed at Day 4. A protocol for the assessment/coding of the affective quality of maternal behaviors indicative of early mother–infant interaction was developed and interculturally validated. Results were compared with birth randomization, as to explain impact of birth practices. Findings indicate that separation and swaddling at birth interfered with mother–infant interaction during a breastfeeding session at Day 4; these mothers significantly demonstrated more roughness in their behaviors with their infants at Day 4. Results also show evidences of a sensitive period for separation after birth. Implications are to encourage immediate and uninterrupted skin-to-skin contact at birth, and rooming-in during postpartum, as recommended in World Health Organization/UNICEF Ten Steps for Successful Breastfeeding.