Nonmaternal Care Research Articles

Hunter-Gatherer children's close-proximity networks: Similarities and differences with cooperative and communal breeding systems.

Among vertebrates, allomothering (non-maternal care) is classified as cooperative breeding (help from sexually mature non-breeders, usually close relatives) or communal breeding (shared care between multiple breeders who are not necessarily related). Humans have been described with both labels, most frequently as cooperative breeders. However, few studies have quantified the relative contributions of allomothers according to whether they are (a) sexually mature and reproductively active and (b) related or unrelated. We constructed close-proximity networks of Agta and BaYaka hunter-gatherers. We used portable remote-sensing devices to quantify the proportion of time children under the age of 4 spent in close proximity to different categories of potential allomother. Both related and unrelated, and reproductively active and inactive, campmates had substantial involvement in children's close-proximity networks. Unrelated campmates, siblings and subadults were the most involved in both populations, whereas the involvement of fathers and grandmothers was the most variable between the two populations. Finally, the involvement of sexually mature, reproductively inactive adults was low. Where possible, we compared our findings with studies of other hunter-gatherer societies, and observed numerous consistent trends. Based on our results we discuss why hunter-gatherer allomothering cannot be fully characterised as cooperative or communal breeding.

Oestrogen treatment restores dentate gyrus development in premature newborns by IGF1 regulation.

Prematurely-born infants cared for in the neonatal units suffer from memory and learning deficits. Prematurity diminishes neurogenesis and synaptogenesis in the hippocampal dentate gyrus (DG). This dysmaturation of neurons is attributed to elevated PSD95, NMDR2A, and IGF1 levels. Since oestrogen treatment plays key roles in the development and plasticity of DG, we hypothesized that 17β-estradiol (E2) treatment would ameliorate neurogenesis and synaptogenesis in the DG, reversing cognitive deficits in premature newborns. Additionally, E2-induced recovery would be mediated by IGF1 signalling. These hypotheses were tested in a rabbit model of prematurity and nonmaternal care, in which premature kits were gavage-fed and reared by laboratory personnel. We compared E2- and vehicle-treated preterm kits for morphological, molecular, and behavioural parameters. We also treated kits with oestrogen degrader, RAD1901, and assessed IGF1 signalling. We found that E2 treatment increased the number of Tbr2+ and DCX+ neuronal progenitors and increased the density of glutamatergic synapses in the DG. E2 treatment restored PSD95 and NMDAR2A levels and cognitive function in preterm kits. Transcriptomic analyses showed that E2 treatment contributed to recovery by influencing interactions between IGF1R and neurodegenerative, as well as glutamatergic genes. ERα expression was reduced on completion of E2 treatment at D7, followed by D30 elevation. E2-induced fluctuation in ERα levels was associated with a reciprocal elevation in IGF1/2 expression at D7 and reduction at D30. ERα degradation by RAD1901 treatment enhanced IGF1 levels, suggesting ERα inhibits IGF1 expression. E2 treatment alleviates the prematurity-induced maldevelopment of DG and cognitive dysfunctions by regulating ERα and IGF1 levels.

Elevated insulin growth factor-1 in dentate gyrus induces cognitive deficits in pre-term newborns.

Prematurely born infants are deprived of maternal hormones and cared for in the stressful environment of Neonatal Intensive Care Units (NICUs). They suffer from long-lasting deficits in learning and memory. Here, we show that prematurity and associated neonatal stress disrupt dentate gyrus (DG) development and induce long-term cognitive deficits and that these effects are mediated by insulin growth factor-1 (IGF1). Nonmaternal care of premature rabbits increased the number of granule cells and interneurons and reduced neurogenesis, suggesting accelerated premature maturation of DG. However, the density of glutamatergic synapses, mature dendritic spines, and synaptic transmission were reduced in preterm kits compared with full-term controls, indicating that premature synaptic maturation was abnormal. These findings were consistent with cognitive deficits observed in premature rabbits and appeared to be driven by transcriptomic changes in the granule cells. Preterm kits displayed reduced weight, elevated serum cortisol and growth hormone, and higher IGF1 expression in the liver and DG relative to full-term controls. Importantly, blocking IGF-1 receptor in premature kits restored cognitive deficits, increased the density of glutamatergic puncta, and rescued NR2B and PSD95 levels in the DG. Hence, IGF1 inhibition alleviates prematurity-induced cognitive dysfunction and synaptic changes in the DG through modulation of NR2B and PSD95. The study identifies a novel strategy to potentially rescue DG maldevelopment and cognitive dysfunction in premature infants under stress in NICUs.

Familial allomaternal care exposure is predictive of infant development.

This study assesses whether increased exposure to allomaternal care (AMC, or non-maternal care) is associated with improved infant motor and social milestone attainment. Typically developing infants aged 13-18 months (n=102) were assessed by their mothers using the previously validated National Center for Health Statistics' Motor and Social Development Scale (MSD). AMC exposure from birth to present was quantified using four AMC predictor components. Exposure to Highly Involved Familial AMC has a significant medium effect on MSD score, such that infants experiencing more of this type of care score higher. Familial AMC is associated with improved milestone attainment, suggesting that learning experiences are enhanced by these interactions, although further cross-cultural studies are needed. If future studies confirm the positive effects of AMC interactions on early developmental outcomes, this may help explain the selective pressures for extensive AMC.

Maternal and non-maternal care in infancy and later child cognitive, language and motor development in Chile: Does type of care matter?

Growing numbers of children across the world start non-maternal care in the first year of life. However, few studies have described how different infant care experiences may relate to later child cognitive, language and motor functioning, and most analyses have focused on samples from historically industrialized regions. Cognitive, language and motor subscores (TEPSI) and receptive vocabulary scores (TVIP) obtained through direct testing of 24-to-48-month-old children (n = 7564) from the Chilean Longitudinal Survey of Early Childhood were compared based on retrospective reports of care received as infants. Children who, as infants, had received one of four types of non-maternal care — center-based, grandparent, other relative, and non-relative care — were compared to those who had exclusively experienced maternal care (71.8%). Series of regressions with propensity score models (PSM) were performed. Compared to maternal care, children in center-based care and grandparent care had higher total TEPSI scores (d = .19, p < 0.05) (d = .19, p < 0.01) and TEPSI language subscores (d = .20, p < 0.05) (d = .20, p < 0.01), while those in grandparent care also had higher TEPSI motor subscores (d = .08, p < 0.05). In contrast, children in non-relative care had lower TVIP receptive vocabulary scores (d = −.38, p < 0.01). These findings contribute to the debate on national policies supporting specific types of non-maternal care and their impact on child development.

Erratum: Reduced Hippocampal Dendrite Branching, Spine Density and Neurocognitive Function in Premature Rabbits, and Reversal with Estrogen or TrkB Agonist Treatment.

Preterm-born children suffer from neurological and behavioral disorders. Herein, we hypothesized that premature birth and non-maternal care of preterm newborns might disrupt neurobehavioral function, hippocampal dendritic arborization, and dendritic spine density. Additionally, we assessed whether 17β-estradiol (E2) replacement or the TrkB receptor agonist, 7,8-dihydroxyflavone (DHF), would reverse compromised dendritic development and cognitive function in preterm newborns. These hypotheses were tested by comparing preterm (E28.5) rabbit kits cared and gavage-fed by laboratory personnel and term-kits reared and breast-fed by their mother doe at an equivalent postconceptional age. Neurobehavioral tests showed that both premature-birth and formula-feeding with non-maternal care led to increased anxiety behavior, poor social interaction, and lack of novelty preference compared with term-kits. Dendritic branching and number of total or mushroom dendritic spines were reduced in the CA1 field of preterm-kits compared with term controls. While CDC42 and Rac1/2/3 expression levels were lower, RhoA-activity was higher in preterm-kits compared with term controls. Both E2 and DHF treatment reversed prematurity-induced reduction in spine density, reduced total RhoA-GTPase levels, and enhanced cognitive function. Hence, prematurity and non-maternal care result in cognitive deficits, and reduced dendritic arbors and spines in CA1. E2 replacement or DHF treatment might reverse changes in dendritic spines and improve neurodevelopment in premature infants.

Reduced Hippocampal Dendrite Branching, Spine Density and Neurocognitive Function in Premature Rabbits, and Reversal with Estrogen or TrkB Agonist Treatment.

Preterm-born children suffer from neurological and behavioral disorders. Herein, we hypothesized that premature birth and non-maternal care of preterm newborns might disrupt neurobehavioral function, hippocampal dendritic arborization, and dendritic spine density. Additionally, we assessed whether 17β-estradiol (E2) replacement or the TrkB receptor agonist, 7,8-dihydroxyflavone (DHF), would reverse compromised dendritic development and cognitive function in preterm newborns. These hypotheses were tested by comparing preterm (E28.5) rabbit kits cared and gavage-fed by laboratory personnel and term-kits reared and breast-fed by their mother doe at an equivalent postconceptional age. Neurobehavioral tests showed that both premature-birth and formula-feeding with non-maternal care led to increased anxiety behavior, poor social interaction, and lack of novelty preference compared with term-kits. Dendritic branching and number of total or mushroom dendritic spines were reduced in the CA1 field of preterm-kits compared with term controls. While CDC42 and Rac1/2/3 expression levels were lower, RhoA-activity was higher in preterm-kits compared with term controls. Both E2 and DHF treatment reversed prematurity-induced reduction in spine density, reduced total RhoA-GTPase levels, and enhanced cognitive function. Hence, prematurity and non-maternal care result in cognitive deficits, and reduced dendritic arbors and spines in CA1. E2 replacement or DHF treatment might reverse changes in dendritic spines and improve neurodevelopment in premature infants.

Enriched early childhood experiences: Latina mothers’ perceptions and use of center-Based child care

Latino children in the U.S., particularly from immigrant families, are less likely than their peers to attend early care and education (ECE) programs, but this trend may be shifting. This study used longitudinal, ethnographic data from Welfare, Children, and Families: A Three City Study to explore low-income Latina immigrant mothers’ ECE decisions, including how they learn about, perceive, and select ECE (N = 31). Results of analysis employing grounded theory and narrative approaches revealed two interesting paradoxes. First, for many mothers, center-based child care was viewed as distinctly different from more informal types of non-maternal care and thus, not perceived as a barrier to family time. Second, mothers praised the learning opportunities and education their children received in formal center-based programs, but rarely linked it to preparation for elementary school or the transition to kindergarten. These results are discussed in terms of consistencies with prior quantitative and qualitative research and new directions for research and policy aimed at promoting the well-being of Latino immigrant children and families.

Nonmaternal care: a half-century of research

This paper aims to serve three purposes, providing: 1. a half-century retrospective on research in on nonmaternal care of the young, with an emphasis on key advances; 2. a commentary on the research papers in this special issue on nonmaternal care; and 3. a summary of nonmaternal care among hunting-and-gathering cultures—representing the human Environments of Evolutionary Adaptedness (EEAs)—in the broader context of human evolution. While the research being done now is excellent and uses appropriate evolutionary theory and cutting-edge methods ranging across behavioral biology (field and laboratory observational studies, controlled experiments, careful behavioral measures, energetics, neurotransmitter function, neuroendocrinology, neuroimaging, and genetics, among others), it is difficult to make generalizations beyond stating that nonmaternal care is a multifaceted evolved function in some species, which usually contributes to the reproductive success of the mother and the survival of the young. Why it evolved when and where it did is not an impenetrable question, but needs further research. The same is true for the mechanistic biology of various types of allomaternal care. I conclude with some observations on historical changes in non-maternal care since the hunting-gathering era, including in industrial and postindustrial cultures. It is evident that in the human species at least, many arrangements for care of the young are possible and adaptive.

With a little help from her friends (and family) part I: the ecology and evolution of non-maternal care in mammals

In the class Mammalia, most young are cared for exclusively by their mothers. In species where mothers receive help, however, non-maternal caregivers may play a crucial role in development and life history trajectories. In turn, recipients of such care may have important impacts on caregivers of all types. In Part I of this overview, we briefly review the evolutionary barriers to widespread non-maternal care in mammals, and explain why the exceptions are of particular theoretical importance. We also summarize the current understanding of the selective forces leading to non-maternal care, and the taxa and types of caretakers amongst which it occurs. Finally, we argue for a fresh look at the categorization schemes that have traditionally been used to separate various types of mammalian non-maternal caregivers. This two-part introduction is aimed at scientists from multiple disciplines who study diverse organismal systems. It draws from the social and biological sciences literatures to provide an overview of this special issue of Physiology and Behavior's suite of methodological offerings and theoretical underpinnings.

With a little help from her friends (and family) part II: Non-maternal caregiving behavior and physiology in mammals

The diversity of competing frameworks for explaining the evolution of non-maternal care in mammals (Part I, this issue) reflects the vast range of behaviors and associated outcomes these theories attempt to subsume. Caretaking comprises a wide variety of behavioral domains, and is mediated by an equally large range of physiological systems. In Part II, we provide an overview of how non-maternal care in mammals is expressed, the ways in which it is regulated, and the many effects such care has on both recipients and caretakers. We also discuss the two primary ways in which closer integration of ultimate and proximate levels of explanation can be useful when addressing questions about non-maternal caretaking. Specifically, proximate mechanisms provide important functional clues, and are key to testing theory concerning evolutionary tradeoffs. Finally, we highlight a number of methodological and publication biases that currently shape the literature, which provide opportunities for knowledge advancement in this domain going forward. In this conclusion to our two-part introduction, we provide a broad survey of the behavior and physiology that the contributions to this special issue represent.

Framing Mothers: Childcare Research and the Normalization of Maternal Care

The National Institute of Child and Human Development Study of Early Child Care and Youth Development (SECCYD), conducted from 1991 to 2009, reveals how the discourse of childcare research normalizes primary maternal care and distinctly gendered parenting responsibilities. Although the SECCYD deliberately challenges the idea that all children and all forms of care are analytically interchangeable, it implicitly accepts the notion that primary maternal care is normal for every child, or the standard by which any other care should be evaluated, by relying on theories, concepts, and methods that position mothers as uniquely responsible for healthy children. Assumptions about the normatively maternal architecture of child development shaped the questions the authors asked, how they went about answering them, and how they interpreted the results. The study ultimately concludes that nonmaternal care does not put children at developmental risk. But it does so by demonstrating that such care neither displaces children’s primary relationship with their mothers nor upsets the normal gender functioning of nuclear families. This normalization arbitrarily limits what constitutes a healthy family by foreclosing the possibility that nonmaternal primary relationships, such as those between a developing child and a father, two fathers, two mothers, grandparents, or any other constellation of caregiving, might offer a distinct and healthy developmental path. It also suggests that the central concepts and outcome measures of psychology discourse on childcare need substantial rethinking.

Age of Entry Into Early Childhood Education and Care as a Predictor of Aggression

Socioemotional risks associated with nonparental care have been debated for decades, and research findings continue to be mixed. Yet few studies have been able to test the causal hypothesis that earlier, more extensive, and longer durations of nonmaternal care lead to more problems. To examine the consequences of age of entry into nonparental care for childhood aggression, we used prospective longitudinal data from Norway, where month of birth partly determines age of entry into Early Childhood Education and Care (ECEC) centers. In this sample of 939 children followed from ages 6 months through 4 years, ECEC teachers reported the children’s aggression when they were 2, 3, and 4 years old. We found some evidence that age of entry into ECEC predicted aggression at age 2, albeit modestly and not robustly. Between the ages of 2 and 4 years, the effect of age of entry on aggression faded to negligible levels. The implications for psychological science and policy are discussed.

Very extensive nonmaternal care predicts mother-infant attachment disorganization: Convergent evidence from two samples.

We examined whether a maximum threshold of time spent in nonmaternal care exists, beyond which infants have an increased risk of forming a disorganized infant-mother attachment. The hours per week infants spent in nonmaternal care at 7-8 months were examined as a continuous measure and as a dichotomous threshold (over 40, 50 and 60 hr/week) to predict infant disorganization at 12-15 months. Two different samples (Austin and NICHD) were used to replicate findings and control for critical covariates: mothers' unresolved status and frightening behavior (assessed in the Austin sample, N = 125), quality of nonmaternal caregiving (assessed in the NICHD sample, N = 1,135), and family income and infant temperament (assessed in both samples). Only very extensive hours of nonmaternal care (over 60 hr/week) and mothers' frightening behavior independently predicted attachment disorganization. A polynomial logistic regression performed on the larger NICHD sample indicated that the risk of disorganized attachment exponentially increased after exceeding 60 hr/week. In addition, very extensive hours of nonmaternal care only predicted attachment disorganization after age 6 months (not prior). Findings suggest that during a sensitive period of attachment formation, infants who spend more than 60 hr/week in nonmaternal care may be at an increased risk of forming a disorganized attachment.

가족관련변인과 영유아발달의 관계 : 종일제 보육과 어머니 단독양육의 비교

본 연구는 영유아기 종일제 어린이집 이용 여부에 따라 가족관련 변인이 영유아발달에 가지는 관계성의 강도가 다를 수 있다는 가설을 검증하는 데에 목적이 있다. 한국아동패널연구의 3차년도 및 4차년도 조사자료를 분석하여 종일제 어린이집을 이용(주당 30시간 이상의 어린이집 이용)집단과 어린이집이나 대리양육자를 이용하지 않는 어머니 단독양육 집단을 추출하여, 일련의 가족관련 변인과 영유아의 발달적 결과 간의 관계성의 양상과 그 강도를 비교하였다. 분석방법으로 이변량 상관관계분석을 실시하였으며 두 집단의 상관계수 간의 유의한 차이를 검증하였다. 연구결과, 만2세의 경우 어머니의 사회적 양육유형이 영아의 의사소통을 정적으로 예측하는데 있어 종일제 어린이집을 사용하는 가족에서 그 크기가 유의하게 큰 것으로 나타났다. 만 3세 때에는 가정환경검사 중 다수의 하위변인에서 어린이집을 이용하지 않는 가족의 경우, 종일제 어린이집을 이용하는 경우에 비해 유의하게 강한 상관관계로 표현어휘 및 수용어휘 발달을 예측하였다. 즉, 어린이집에서 시간을 보내는 경우, 가정환경 외에 다른 요인이 발달을 예측할 수 있음을 시사한다. 하지만 이들 변인 외에 분석에 사용된 다양한 변인과 영유아 발달 간의 상관관계에 집단차는 발견되지 않아 발달에 기여하는 가족과정이 종일제 어린이집과 어머니 단독양육 집단 간에 유사 또는 차별적이라고 단순히 결론 내릴 수 없고, 발달연령, 가족과정 내의 예측요인, 그리고 발달적 결과에 따라 다소 복잡한 유형으로 차이를 보임을 알 수 있다. This study aims to examine the suggestions by studies that family predictors are related to developmental outcomes more strongly for children reared principally by their parents compared to those with extensive child care experience. Zero-order correlations between family predictors and developmental outcomes were conducted and the significance of differences in correlation coefficients between the two child care groups were examined. There was no evidence that there exist systematic differences between the two groups in predictive power of family factors except a few exceptions. At 2 years, social parenting style was more strongly associated with communication ability in the extensive child care group. At 3 years, some HOME subscales were related to a child's expressive and receptive vocabulary skills in significantly greater magnitudes in the mother care group. The findings also implied the potential contribution of child care environment on developmental outcomes for those who spend extensive hours in nonmaternal care.

Nonmaternal care hours and temperament predict infants’ proximity-seeking behavior and attachment subgroups

Using the NICHD Early Childcare dataset (N=1281), this study examined whether infant temperament and the amount of time infants spend in nonmaternal care independently predict (1) the likelihood that they seek comfort from their mother when needed and (2) placement in a particular subgroup of infant-mother attachment patterns. Mothers reported the number of hours their infant spent in nonmaternal care each month and their infant's difficulty adapting to novel stimuli at 6 months. The degree to which 15-month-old infants seek comfort from their mother during reunion episodes in the Strange Situation was observed using two behavioral scales (“proximity seeking” and “contact maintaining”). Their average score forms the outcome variable of “proximity-seeking behavior.” The other outcome variables were the subgroups of infant-mother attachment patterns: two subgroups for insecure babies (resistant and avoidant) and four subgroups for secure babies (B1, B2, B3, and B4). Easy adaptability to novel stimuli and long hours of nonmaternal care independently predicted a low level of proximity-seeking behavior. These predictors also increased the likelihood of an insecure infant being classified as avoidant (vs. resistant). A secure infant with these same predictors was most likely to be classified as B1, followed by B2, and then B3, with B4 being the least likely classification. Although previous studies using the NICHD dataset found that hours of nonmaternal care had no main effect on infants’ attachment security (vs. insecurity), this study demonstrates that hours of nonmaternal care predict the subcategories of infant-mother attachment.

"Auf die Familie kommt es an". Familienorientierte Frühförderung und inklusive Krippenförderung

The current state of research suggests that early day care services for children with and without disabilities have no negative consequences for child development, if quality of care is well enough. However, the quality of family relations has more effect on child development than day care. According to our view, this fact has special relevance for children with disabilities. We propose that children with disabilities should not visit day care settings before their second birthday and the amount of time in nonmaternal care should be restricted if there are no severe additional social risks. Early intervention services should support the coping skills of families as well as the professional skills of day care providers to adapt to the special needs of this group of children. Implications of this position are discussed.

Nonmaternal Care's Association With Mother's Parenting Sensitivity: A Case of Self‐Selection Bias?

Although attachment theory posits that the use of nonmaternal care undermines quality of mothers' parenting, empirical evidence for this link is inconclusive. Using data from the National Institute of Child Health and Human Development Study of Early Child Care and Youth Development (N = 1,233), the authors examined the associations between nonmaternal care characteristics and maternal sensitivity during the first 3 years of children's lives, with special attention to selection effects and moderation by resource levels. Findings from fixed-effects regression models suggested that, on average, there is little relationship between nonmaternal care characteristics and maternal sensitivity, once selection factors are held constant. Some evidence of moderation effects was found, however. Excellent-quality care is related to more sensitivity for mothers with lower family income. Poor-quality care is related to lower sensitivity for single mothers, but not partnered mothers. In sum, nonmaternal care characteristics do not seem to have as much influence on mothers' parenting as attachment theory claims.

Moving beyond the child care debate toward implications for social and political agendas

Abstract Early nonmaternal child care, for at least some portion of the week, is now the reality for most families in the United States. Ongoing debates surrounding what these changes mean for our society have focused on the possible negative consequences of extended nonmaternal care and the potential impact of such arrangements on children's later development. The NICHD-Early Child Care Research Network (ECCRN) Study of Early Child Care and Youth Development has made great strides toward addressing methodological limitations in previous research through a series of landmark examinations of child functioning from transition to school through 15 years-of-age. The primary goal of this commentary is to put the child care findings into a broader developmental, social, and political context by reframing the discussion to move beyond the current daycare debate and consider implications for social policy and research agendas. Given that daycare has become a normative social institution, we first consider what the research findings mean for the healthy social–emotional and cognitive growth of children. Second, we articulate the implications of the data for social interventions to improve those outcomes. Finally, we address the issue of what political changes are necessary to produce those improvements.

One-Year-Olds' Proximity-Seeking Behavior in the Strange Situation: Its Links to Hours of Nonmaternal Care

One-Year-Olds' Proximity-Seeking Behavior in the Strange Situation: Its Links to Hours of Nonmaternal Care