Effects of motherhood on physiological and subjective responses to infant cries in teenage mothers: a comparison with non-mothers and adult mothers

The present study was designed to determine whether becoming a mother during the adolescent period changes maternal responsiveness or maternal motivation, assessed through hormonal, autonomic, and hedonic responses to recorded infant cries and interactions with their babies. Fifty-six teen mothers were compared to 58 teen non-mothers and 49 adult mothers. Teen mothers reported more sympathy and alertness in response to recorded infant cries compared to non -mother teens; however, among the teen women there were no differences between mothers and non-mothers in heart rate and cortisol responses to infant cries. In contrast, in comparison to adult mothers, teen mothers reported the same levels of sympathy and alertness to infant cries; however, adult mothers showed an 'alerted' pattern of heart rate and cortisol response to infant cries not seen in the teen mother group. Inclusion of the covariate, fathers' employment classification as an index of SES or time of testing and cortisol sampling did not affect this pattern of results. Taken together, these results show that where self-report is used as a measure of maternal responsiveness, teen mothers are no different in responsiveness than adult mothers; however, where physiological and interactional measures of responsiveness are considered, teen mothers are less likely to show heightened or selective responses to infant cries or respond 'attentively' to the infant.     

Attentional Prioritization of Infant Faces Is Limited to Own-Race Infants

Background

Recent evidence indicates that infant faces capture attention automatically, presumably to elicit caregiving behavior from adults and leading to greater probability of progeny survival. Elsewhere, evidence demonstrates that people show deficiencies in the processing of other-race relative to own-race faces. We ask whether this other-race effect impacts on attentional attraction to infant faces. Using a dot-probe task to reveal the spatial allocation of attention, we investigate whether other-race infants capture attention.

Principal Findings

South Asian and White participants (young adults aged 18–23 years) responded to a probe shape appearing in a location previously occupied by either an infant face or an adult face; across trials, the race (South Asian/White) of the faces was manipulated. Results indicated that participants were faster to respond to probes that appeared in the same location as infant faces than adult faces, but only on own-race trials.

Conclusions/Significance

Own-race infant faces attract attention, but other-race infant faces do not. Sensitivity to face-specific care-seeking cues in other-race kindenschema may be constrained by interracial contact and experience.     

Emotional Processing of Infants Displays in Eating Disorders

Aim

The aim of this study is to examine emotional processing of infant displays in people with Eating Disorders (EDs).

Background

Social and emotional factors are implicated as causal and maintaining factors in EDs. Difficulties in emotional regulation have been mainly studied in relation to adult interactions, with less interest given to interactions with infants.

Method

A sample of 138 women were recruited, of which 49 suffered from Anorexia Nervosa (AN), 16 from Bulimia Nervosa (BN), and 73 were healthy controls (HCs). Attentional responses to happy and sad infant faces were tested with the visual probe detection task. Emotional identification of, and reactivity to, infant displays were measured using self-report measures. Facial expressions to video clips depicting sad, happy and frustrated infants were also recorded.

Results

No significant differences between groups were observed in the attentional response to infant photographs. However, there was a trend for patients to disengage from happy faces. People with EDs also reported lower positive ratings of happy infant displays and greater subjective negative reactions to sad infants. Finally, patients showed a significantly lower production of facial expressions, especially in response to the happy infant video clip. Insecure attachment was negatively correlated with positive facial expressions displayed in response to the happy infant and positively correlated with the intensity of negative emotions experienced in response to the sad infant video clip.

Conclusion

People with EDs do not have marked abnormalities in their attentional processing of infant emotional faces. However, they do have a reduction in facial affect particularly in response to happy infants. Also, they report greater negative reactions to sadness, and rate positive emotions less intensively than HCs. This pattern of emotional responsivity suggests abnormalities in social reward sensitivity and might indicate new treatment targets.     

Sex differences in visual attention toward infant faces

Parental care and alloparental care are major evolutionary dimensions of the biobehavioral repertoire of many species, including human beings. Despite their importance in the course of human evolution and the likelihood that they have significantly shaped human cognition, the nature of the cognitive mechanisms underlying alloparental care is still largely unexplored. In this study, we examined whether one such cognitive mechanism is a visual attentional bias toward infant features, and if so, whether and how it is related to the sex of the adult and the adult’s self-reported interest in infants. We used eye-tracking to measure the eye movements of nulliparous undergraduates while they viewed pairs of faces consisting of one adult face (a man or woman) and one infant face (a boy or girl). Subjects then completed two questionnaires designed to measure their interest in infants. Results showed, consistent with the significance of alloparental care in human evolution, that nulliparous adults have an attentional bias toward infants. Results also showed that women’s interest in and attentional bias towards infants were stronger and more stable than men’s. These findings are consistent with the hypothesis that, due to their central role in infant care, women have evolved a greater and more stable sensitivity to infants. The results also show that eye movements can be successfully used to assess individual differences in interest in infants.     

A specific and rapid neural signature for parental instinct

Darwin originally pointed out that there is something about infants which prompts adults to respond to and care for them, in order to increase individual fitness, i.e. reproductive success, via increased survivorship of one's own offspring. Lorenz proposed that it is the specific structure of the infant face that serves to elicit these parental responses, but the biological basis for this remains elusive. Here, we investigated whether adults show specific brain responses to unfamiliar infant faces compared to adult faces, where the infant and adult faces had been carefully matched across the two groups for emotional valence and arousal, as well as size and luminosity. The faces also matched closely in terms of attractiveness. Using magnetoencephalography (MEG) in adults, we found that highly specific brain activity occurred within a seventh of a second in response to unfamiliar infant faces but not to adult faces. This activity occurred in the medial orbitofrontal cortex (mOFC), an area implicated in reward behaviour, suggesting for the first time a neural basis for this vital evolutionary process. We found a peak in activity first in mOFC and then in the right fusiform face area (FFA). In mOFC the first significant peak (p<0.001) in differences in power between infant and adult faces was found at around 130 ms in the 10-15 Hz band. These early differences were not found in the FFA. In contrast, differences in power were found later, at around 165 ms, in a different band (20-25 Hz) in the right FFA, suggesting a feedback effect from mOFC. These findings provide evidence in humans of a potential brain basis for the "innate releasing mechanisms" described by Lorenz for affection and nurturing of young infants. This has potentially important clinical applications in relation to postnatal depression, and could provide opportunities for early identification of families at risk.     

The motivational salience of infant faces is similar for men and women

Infant facial features are thought to be powerful elicitors of caregiving behaviour. It has been widely assumed that men and women respond in different ways to those features, such as a large forehead and eyes and round protruding cheeks, colloquially described as 'cute'. We investigated experimentally potential differences using measures of both conscious appraisal ('liking') and behavioural responsivity ('wanting') to real world infant and adult faces in 71 non-parents. Overall, women gave significantly higher 'liking' ratings for infant faces (but not adult faces) compared to men. However, this difference was not seen in the 'wanting' task, where we measured the willingness of men and women to key-press to increase or decrease viewing duration of an infant face. Further analysis of sensitivity to cuteness, categorising infants by degree of infantile features, revealed that both men and women showed a graded significant increase in both positive attractiveness ratings and viewing times to the 'cutest' infants. We suggest that infant faces may have similar motivational salience to men and women, despite gender idiosyncrasies in their conscious appraisal.     

Manipulation of Infant‐Like Traits Affects Perceived Cuteness of Infant,Adult and Cat Faces

Physical traits that are characteristic of human infants are referred to as baby‐schema, and the notion that these affect perception of cuteness and elicit care giving from adults has a long history. In this study, infant‐similarity was experimentally manipulated using the difference between adult and infant faces. Human infant, human adult and cat faces were manipulated to look more (human) infant‐like or adult‐like. The results from the current study demonstrate the impact of infant‐similarity on human adults' perception of cuteness across the three different types of face. The type of face had a large impact on perceived cuteness in line with the expected infant‐similarity of the images. Infants and cats were cutest while adults were less cute. The manipulations of infant‐similarity, however, had similar effects on the perception of cuteness across all three types of face. Faces manipulated to have infant‐like traits were rated as cuter than their equivalents manipulated to have adult‐like traits. These data demonstrate that baby‐like traits have a powerful hold over human perceptions and that these effects are not simply limited to infant faces.     

Mating season effects on mother-infant conflict in Japanese macaques,Macaca fuscata

The impact of seasonal mating on the mother-infant relationship during the first year of the infant's life was documented in a confined troop of Japanese macaques. During the weeks in which the mothers were being mounted, negative behaviour directed towards the infants increased. As maternal rejections and punishments escalated, the infants displayed regressive behaviour (showing signs of distress more frequently). Infants also groomed their mothers at an increased rate at this time. Behaviour that indicated increased independence did not show increases during this time. Moreover, behaviour negatively associated with independence, such as ventral contact and proximity to the mother, remained stable throughout this time period. The mother-infant relationship undergoes a period of conflict during the mating season not because the mother is weaning her infant, but because it is to her reproductive advantage to regulate the times in which the infant is allowed to suckle.     

Ecological immunity of human milk: Life history perspectives from the United States and Kenya

Objectives

Previous research has established population variation in anti‐inflammatory immunological biomarkers in human milk. This immunity is potentially ecology‐dependent and may alter the life history trade‐off between growth and maintenance in infants. The current study has two aims: (1) to assess the ecological differences in milk immunity in two populations, one from the urban U.S. and one from rural Kenya; and (2) to test the hypothesis that milk immunity can affect infant growth indicators.

Materials and Methods

Kenyan Ariaal (n = 233) and U.S. (n = 75) breastfeeding mother‐infant pairs participated in a cross‐sectional study at two separate field sites. Laboratory analysis was performed on milk for the anti‐inflammatory biomarkers TGF‐β2, sTNF‐αRI, sTNF‐αRII, and IL‐1ra using ELISA. Multiple imputation was used to extrapolate data below the limit of detection before multivariate analysis.

Results

There were significant differences between U.S. and Kenyan mothers on all four milk biomarkers, with Kenyan mothers having significantly higher sTNF‐αRI and sTNF‐αRII and lower TGF‐β2 and IL‐1ra than U.S. mothers. U.S. mothers with higher milk TGF‐β2 and IL‐1ra have infants that are significantly longer and heavier for their age, while Kenyan mothers with higher sTNF‐αRI have significantly longer and heavier infants for their age, and those with higher TGF‐β2 have marginally significantly longer infants.

Discussion

There were significant differences in ecological milk immunity between U.S. and Kenyan mothers. These differences potentially play a role in the growth of their infants. Further research in milk immunity should consider the possibility of shared maternal–infant life histories.

     

The response of some prosimian primate mothers to their own anesthetized infants

Six lemur mothers of three different species and oneGalago crassicaudatus mother were observed in the presence of their own anesthetized infants. Two of the lemur mothers spent only very brief periods sitting near their infants and seldom groomed them; the other four spent over half of the infant immobility period in close proximity to their infants and groomed them frequently. Four lemur mothers groomed the ano-genital region of their infant at least once. None of the lemur mothers picked up or carried her immobilized infant, as has been reported for some higher primate mothers, although one lemur mother used her hands to pull the infant toward her ventrum while sitting on the floor. Five lemur mothers rejected their infants when the infants displayed disoriented behavior while emerging from anesthesia. The galago mother retrieved her anesthetized infant in her jaws but dropped the infant several times while attempting to groom it. These results suggest very tentatively that prosimian mothers lack the ability shown by mothers of some higher primate species to improvise protective ways of behaving toward helpless infants.     

Tail raising by baboon mothers toward immigrant males

Behavioral responses of adult females to recently immigrated adult males were examined in two groups of chacma baboons in the Moremi Wildlife Reserve, Botswana. Mothers carrying infants respond negatively by raising their tails, avoiding, and screaming when in proximity to immigrant males. These responses are not given by mothers when their infants are away from them or by females who do not have infants. Also, the negative responses by mothers carrying infants are given only to immigrant males and not to long-term resident males. These observations are in concordance with the growing evidence of infanticide in savanna baboon societies: mothers would be expected to show negative responses to potentially aggressive males, particularly immigrants. There was evidence to suggest that mothers respond negatively to immigrants only insofar as these males could not have sired their infants. If confirmed by subsequent observations, this result would lend support to the sexual selection model of infanticide.     

Adoption of single and multiple infants by rhesus monkey mothers

Adoption was studied inMacaca mulatta. Multiparous mothers were separated from their biological offspring within hours following parturition, and 2 1/2 days later, on the average, they were offered neonates for adoption. These foster infants had been separated from their biological mothers shortly after birth and averaged 2 3/4 days old when subjected to adoption. Mothers that were offered a single neonate immediately and completely adopted the foster infant. But mothers that were offered two infants at the same time were ambivalent. Many infants were rejected initially, although with one partial exception, the mothers eventually accepted and cared for two infants. It was concluded that the macaque maternal affectional system may be biased toward accepting and nurturing one infant at a time.     

Determinants of breastfeeding initiation among mothers in Kuwait

Background

Exclusive breastfeeding is recommended as the optimal way to feed infants for the first six months of life. While overall breastfeeding rates are high, exclusive breastfeeding is relatively uncommon among Middle Eastern women. The objective of this study was to identify the incidence of breastfeeding amongst women in the six governorates of Kuwait and the factors associated with the initiation of breastfeeding.

Methods

A sample of 373 women (aged 17-47 years), recruited shortly after delivery from four hospitals in Kuwait, completed a structured, interviewer-administered questionnaire. Multivariate logistic regression analysis was used to identify those factors independently associated with the initiation of breastfeeding.

Results

In total, 92.5% of mothers initiated breastfeeding and at discharge from hospital the majority of mothers were partially breastfeeding (55%), with only 30% of mothers fully breastfeeding. Prelacteal feeding was the norm (81.8%) and less than 1 in 5 infants (18.2%) received colostrum as their first feed. Only 10.5% of infants had been exclusively breastfed since birth, the remainder of the breastfed infants having received either prelacteal or supplementary infant formula feeds at some time during their hospital stay. Of the mothers who attempted to breastfeed, the majority of women (55.4%) delayed their first attempt to breastfeed until 24 hours or more after delivery. Breastfeeding at discharge from hospital was positively associated with paternal support for breastfeeding and negatively associated with delivery by caesarean section and with the infant having spent time in the Special Care Nursery.

Conclusions

The reasons for the high use of prelacteal and supplementary formula feeding warrant investigation. Hospital policies and staff training are needed to promote the early initiation of breastfeeding and to discourage the unnecessary use of infant formula in hospital, in order to support the establishment of exclusive breastfeeding by mothers in Kuwait.     

Relationship Between Infant and Mother Circadian Rest-Activity Rhythm Pre- and Postpartum,in Comparison to an Infant With Free-Running Rhythm

Some infants show a free-running rhythm in their rest-activity. We do not know why, nor do we know exactly what the entrainment factors are for the development of the normal 24-h rest-activity rhythm. Actigraphic recordings on 10 primiparae during late pregnancy and these mothers and their infants during the 2nd, 6th, and 12th wks after birth were made over 3–5 continuous days to investigate maternal and infant entrainment. One infant showed a free-running rest-activity circadian rhythm. In late pregnancy, the period in the autocorrelogram of the mother with the free-running infant was longer than the significant period of the mean autocorrelogram of the mothers with non-free-running infants. The finding of this study indicates the free-running rhythm of infant is not reset by maternal entrainment factors. (Author correspondence: nishihara-kk@igakuken.or.jp)     

Social behavior of infant and mother Japanese Macaques (Macaca fuscata): Effects of kinship,partner sex,and infant sex

The behavioral interactions of 22 infant and mother Japanese macaques with other group members were studied. Focal-animal observations were made from the time of each infant’s birth until 1 year of age. Infants and mothers both displayed exceedingly strong preferences for associating with matrilineal kin and, specifically, for female kin. The degree of genetic relatedness was positively correlated with levels of spatial proximity, contact, grooming, aggression, and play. Overall frequencies of interactions with nonkin were very low, and partner sex was not an important factor in interactions with nonkin. There were no significant differences between male and female infants in interactions with kin versus nonkin. There was only one significant difference between male and female infants in interactions with males versus females: female infants showed stronger preferences for initiating proximity with females over males than did male infants. Because mothers provide the focal point for infant interactions during the first year of life, we compared the behavior of infants and mothers. Mothers were the recipients of more social interactions than were infants, mothers engaged in more grooming than did infants, and infants engaged in more social play than did mothers. These findings are only partially consistent with kin-selection theory, and the inadequacies of studying matrilineal kin discrimination to test kin selection are reviewed. The near-absence of infant sex differences in associations with social partners suggests that although maternal kin other than the mother are important to infant socialization, they probably do not contribute to the development of behavioral sex differences until after the first year of life.     

Inappropriate infant feeding practices of HIV-positive mothers attending PMTCT services in Oromia regional state,Ethiopia: a cross-sectional study

Background

Inappropriate infant feeding affects the probability of mother-to-child transmission of HIV and HIV-free survival of infants. However, in Ethiopia limited evidence exists regarding the infant feeding practice of mothers who are HIV-positive. The aim of this study was to determine the prevalence and predictors of inappropriate infant feeding among HIV-positive mothers attending the prevention of mother-to-child transmission (PMTCT) service in Adama and Bushoftu towns, Oromia, central Ethiopia.

Methods

A cross-sectional study was conducted in ten PMTCT service providing health facilities in the towns; 283 mother-infant pairs were enrolled. Appropriate infant feeding practice was defined as exclusive breastfeeding in the first six months of age. Logistic regression was employed to analyze the data and the outputs are presented using adjusted odds ratio (AOR) with 95% confidence intervals (CI).

Results

One hundred thirty of the infants were aged below six months, 103 between 6 and 11 months and 50 were older than 12 months. The prevalence of inappropriate infant feeding was 14.5% (95% CI 10.6, 18.7). About 6.3% and 8.3% practiced exclusive replacement feeding and mixed feeding respectively, in the first six months. Only 1.8% ever expressed their breast milk to feed their baby and none practiced wet nursing. Among 38 mothers who already discontinued breastfeeding 52.6% did so before 12 months of age. Mothers who were HIV-positive and had received antenatal (AOR?=?0.05: 0.01, 0.30) and postnatal visits (AOR?=?0.18: 0.04, 0.81); received infant feeding counseling (AOR?=?0.18: 0.06, 0.55); and disclosed their HIV status to their partners (AOR?=?0.28: 0.12, 0.63), showed a reduction of practicing inappropriate infant feeding. Mothers having breast problems (AOR?=?4.89: 1.54, 15.60) and infants with mouth ulcers (AOR?=?6.41: 2.07, 19.85) were more likely to practice inappropriate feeding.

Conclusion

Prompt management of breast complaints in mothers and mouth ulcer in infants; and provision of nutrition counseling to HIV-positive mothers, especially during antenatal and postnatal care, may help to improve the infant feeding practices for HIV exposed infants.

     

Maternal mental health and its association with infant growth at 6 months in ethnic groups: results from the Born-in-Bradford birth cohort study

Objective

To identify factors associated with infant growth up to 6 months, with a particular focus on maternal distress, and to explore the effect of ethnicity on any relation between maternal distress and infant growth.

Methods

Cohort study recruiting White and Pakistani women in the United Kingdom (UK). Infant growth was measured at birth and 6 months. Standard assessment of mental health (GHQ-28) was undertaken in pregnancy (26–28 weeks gestation) and 6 months postpartum. Modelling included social deprivation, ethnicity, and other known influences on infant growth such as maternal smoking and alcohol consumption.

Results

Maternal distress improved markedly from pregnancy to 6 months postpartum. At both times Pakistani women had more somatic and depression symptoms than White women. Depression in pregnancy (GHQ subscale D) was associated with lower infant growth at 6 months. Self-reported social dysfunction in pregnancy (GHQ subscale C) was associated with lower gestational age.. Pakistani women reported higher GHQ scores during pregnancy associated with smaller infants at birth. They lived in areas of higher social deprivation, reported less alcohol consumption and smoking postnatally, all independent influences on growth at 6 months.

Conclusions

Maternal mental health in pregnancy is an independent influence on infant growth up to 6 months and is associated with ethnicity which was itself associated with deprivation in our sample. There is a complex relationship between symptoms of maternal distress, ethnicity, deprivation, health behaviours, and early infant growth. Measures should include both emotional and somatic symptoms and interventions to reduce risks of poor early growth need to include psychological and social components.