Do grandparents compete with or support their grandchildren? In Guatemala, paternal grandmothers may compete, and maternal grandmothers may cooperate

Variation in grandmaternal investment in Ukraine

BACKGROUND

Grandmothers vary in their contributions to grandchildren based on their relatedness and the sex of the child. Maternal grandmothers decrease grandchildren's risk of mortality and increase grandchildren's health more significantly than paternal grandmothers, but limited evidence suggests that paternal grandmothers may invest more in female than male grandchildren.

AIMS

In this study, I test whether contact frequency between grandmothers and grandchildren is influenced by their relatedness (maternal vs paternal) or the sex of the child. This research was carried out in Ukraine because it is neither matrilocal nor patrilocal, and Ukrainian grandmothers are known to provide a high rate of childcare.

METHODS

This study included interviews with 60 grandmothers that asked about contact frequency with grandchildren, relatedness (maternal or paternal), and contact frequency between the grandchild and the other grandmother. A dataset generated for each grandchild (n = 128) included sex, age, and contact frequency with both maternal and paternal grandmothers. Linear mixed models were fit to the data to explore the relationship between grandmother relatedness and contact frequency.

RESULTS

On average, maternal grandmothers saw their grandchildren 173.8 days/year, while paternal grandmothers saw their grandchildren 87.5 days/year (p < 0.001). The sex of the child was not a significant factor in determining contact frequency.

CONCLUSION

In Ukraine, maternal grandmothers have more frequent contact with their grandchildren. This finding supports the idea that grandmaternal investment is an evolutionarily adaptive strategy. However, the bias towards maternal grandmothers may also be explained by a post-socialist cultural context, which necessitates grandmaternal care.

Grandmother effects over the Finnish demographic transition

Demographic transitions are defining events for human societies, marking shifts from natural mortality and fertility rates to the low rates seen in industrialised populations. These transitions can affect trait evolution through altering the direction and strength of selection when variance in fertility and mortality decline. One key feature of human evolution is the evolution of extended post-reproductive life through indirect fitness benefits from grandmothering. Although studies in pre- and post-transition societies have documented beneficial grandmother presence, it remains unknown whether these associations changed before, during, or after the transition. Here, we use genealogical data from eighteenth- to twientieth-century Finland to show grandmother-associated changes of two measures of evolutionary fitness (grandchild survival and birth rate) over the transition. We find that grandmothers had greater opportunity to help as the transition progressed, but their effect on grandchild survival declined alongside general mortality rates, implying that selection on lifespan from grandmothering declined too. Whilst grandmother presence was still associated with reduced birth intervals and hence more grandchildren born post-transition, the nature of this relationship changed greatly. This suggests that although potential for intergenerational interactions increased over the demographic transition, the (hypothesised) evolutionary importance of these interactions declined, which reduced selection for extended post-reproductive lifespan.

Maternal grandmothers buffer the effects of ethnic discrimination among pregnant Latina mothers

Ethnic discrimination during pregnancy is linked to maternal psychological distress, adverse birth outcomes and increased offspring morbidity and mortality. An evolutionary perspective reframes offspring health issues as a risk to maternal fitness. We argue that kin may be evolutionarily motivated to buffer psychosocial stressors for the mother during pregnancy. Previously, we found that the relationship of a pregnant woman with her own mother (fetus' maternal grandmother) had a positive association on maternal prenatal psychology, above and beyond her relationship with her fetus' father. Here, we ask if grandmothers buffer mothers' prenatal psychological distress from ethnic discrimination. Using self-report data collected from 216 pregnant Latina women living in Southern California, we found discrimination to be significantly, positively associated with depression, anxiety, and stress in linear regression models. Maternal grandmother communication attenuated the association of discrimination and all three psychological distress measures, adjusting for the mother's relationship with the father. Maternal grandmother emotional support similarly significantly moderated the relationship of discrimination with depression and anxiety. We did not observe any significant interactions for paternal grandmother relationships. Geographic proximity was not a significant stress buffer. Results suggest the important role maternal grandmothers play in perinatal mental health, and that these benefits exist uncoupled from geographic proximity.

Factors Affecting Thai Fathers' Self-Efficacy to Support Exclusive Breastfeeding

BACKGROUND

Breastfeeding is the ideal approach for feeding infants and is an important public health consideration. Successful exclusive breastfeeding initiation and duration is influenced by fathers' support. Paternal self-efficacy to support breastfeeding has also been shown to mediate infant feeding practices. The aim of this study was to investigate factors associated with Thai fathers' self-efficacy to support maternal exclusive breastfeeding.

METHODS

We adopted a cross-sectional survey design for this study. In total, 215 Thai fathers who had a partner with a term (37-42 weeks) pregnancy participated in the study. Data were collected from antenatal care clinics at two hospitals in Northern Thailand between June and August 2022. Participants completed a sociodemographic questionnaire, the Fathers' Attitude toward Exclusive Breastfeeding questionnaire, the Fathers' Knowledge about Exclusive Breastfeeding questionnaire, and the Breastfeeding Self-Efficacy Scale (Short-Form). Multiple linear regression and hierarchical regression were used to analyze factors influencing Thai fathers' self-efficacy to support maternal exclusive breastfeeding.

RESULTS

The mean breastfeeding self-efficacy score was 52.94 (SD = 8.58), indicating that fathers were confident they were able to support their partners' breastfeeding. Regression analysis revealed family type, fathers' attitude toward, and fathers' knowledge about exclusive breastfeeding significantly explaining 14.90% of the variance in paternal breastfeeding support self-efficacy. However, fathers' age, education, employment, income, and number of living children were not associated with their self-efficacy.

CONCLUSIONS

The results demonstrated that family type and fathers' attitudes/knowledge about breastfeeding influenced their self-efficacy to support exclusive breastfeeding. Nurses should consider implementing breastfeeding interventions specific to fathers to enhance their attitudes and knowledge about breastfeeding, including increasing fathers' self-efficacy to support maternal exclusive breastfeeding efforts.

Adoption, Fostering, and Parental Absence in Vanuatu

Alloparenting, wherein people provide care to children who are not their biological offspring, is a key aspect of human child-rearing. In the Pacific, many children are adopted or fostered by custodial alloparents even when both biological parents are still alive. From a behavioral ecology perspective, such behaviors are puzzling: why parent someone else's child at your expense? Furthermore, little is known about how these arrangements are made in Pacific Islander societies today, who provides care, and what kinds of outcomes fostered children experience. A better understanding of these proximate factors may help reveal the ultimate drivers behind custodial alloparenting. Here, we report findings from a survey carried out with the caregivers of 282 children in rural areas of Vanuatu, an island nation in Melanesia. Most fostered and adopted children lived with relatives such as aunts, uncles, and grandparents (87.5%) rather than unrelated caregivers, with a strong preference for maternal kin. The most common reasons for these arrangements were that the parents had separated (16.7%), were engaging in labor migration (27.1%), or a combination of both (27.1%). Results for investment in children's education and their educational outcomes were mixed, although children removed from crisis situations did more poorly than children removed for aspirational reasons. Our findings suggest that custodial alloparenting helps families adapt to socioeconomic transitions and changing marriage practices. Outcomes may depend on a range of factors, such as the reason children were transferred out of the natal home to begin with.

How prenatal cortisol levels relate to grandmother-mother relationships among a cohort of Latina women

INTRODUCTION

As part of the human reproductive strategy, mothers receive childcare assistance from others. For kin, allomothers are adaptively incentivized to provide assistance due to inclusive fitness benefits. Previous studies across a broad range of populations identify grandmothers as particularly consistent allomothers. Minimal attention has been paid to the possibility that allomothers may begin investing in offspring quality during the prenatal stage of life. Here, we innovate within the area of grandmother allocare research by examining the prenatal stage of life and biopsychosocial mechanisms by which prenatal grandmother effects may be enacted.

METHODS

Data derive from the Mothers' Cultural Experiences study, a cohort of 107 pregnant Latina women in Southern California. At <16 weeks' gestation, we administered questionnaires, collected morning urine samples, and measured cortisol by enzyme-linked immunosorbent assay, correcting for specific gravity. We measured the soon-to-be maternal and paternal grandmothers' relationship quality, social support, frequency of seeing each other, communicating, and geographic proximity to pregnant mothers, that is, their daughters and daughters-in-law. These measures were self-reported by the pregnant mothers. We assessed how grandmother constructs related to the pregnant women's depression, stress, anxiety, and cortisol levels.

RESULTS

We observed benefits conferred by maternal grandmothers for mothers' prenatal mental health and lower cortisol levels. Paternal grandmothers also conferred mental health benefits to pregnant daughters-in-law, but higher cortisol levels.

CONCLUSION

Our results suggest that grandmothers, especially maternal grandmothers, are able to improve their inclusive fitness by caring for pregnant daughters, and allomother support may positively impact prenatal health. This work extends the traditional cooperative breeding model by identifying a prenatal grandmother effect, and, by examining a maternal biomarker.

Are menopause, aging and prostate cancer diseases?

There is no doubt that prostate cancer is a disease. Then, according to hyperfunction theory, menopause is also a disease. Like all age-related diseases, it is a natural process, but is also purely harmful, aimless and unintended by nature. But exactly because these diseases (menopause, prostate enlargement, obesity, atherosclerosis, hypertension, diabetes, presbyopia and thousands of others) are partially quasi-programmed, they can be delayed by slowing aging. Is aging a disease? Aging is a quasi-programmed disease that is partially treatable by rapamycin. On the other hand, aging is an abstraction, a sum of all quasi-programmed diseases and processes. In analogy, the zoo consists of animals and does not exist without animals, but the zoo is not an animal.

Do maternal grandmothers influence breastfeeding duration and infant nutrition? Evidence from Merida, Mexico

OBJECTIVES

Breast-feeding is sensitive to somatic, hormonal, behavioral and psychological components of maternal capital. However, through grandmothering, older women may also influence breast-feeding by transferring informational resources to their daughters. We hypothesized that mothers with prolonged instrumental support from their own mother are more likely to have received advice and to have favorable attitudes/practices regarding breastfeeding, compared to those lacking such support, with implications for the grandchild's somatic capital.

METHODS

We recruited 90 mother-infant dyads (52 with grandmaternal support, 38 without) in Merida, Yucatan, Mexico. All children were first-borns, aged ~2 years. Anthropometry and body composition were assessed. Data on grandmother's breastfeeding advice and maternal breastfeeding duration were obtained by questionnaire. Maternal attitudes to breast-feeding were assessed using the Iowa Infant Feeding Attitude Scale.

RESULTS

Women with instrumental support were more likely to have received grandmaternal advice during pregnancy/infancy on exclusive breast-feeding duration (60% vs. 37%, p = 0.033) and the type of first complementary food (81% vs. 47%, p = 0.001). However, women with support had a less favorable attitude to breastfeeding than those without and breastfed their children for less time (median 5 vs. 10.5 months, p = 0.01). No group differences were found in children's length, weight, skinfolds or lean mass z-score.

DISCUSSION

Although grandmothers providing instrumental support provided advice regarding breastfeeding, their attitudes may reflect issues beyond nutritional health. Advice of maternal grandmothers did not promote extended breastfeeding, however the differences in breastfeeding attitudes were not associated with the children's nutritional status. Grandmothers should be included in public health interventions promoting breastfeeding.

Matrilateral bias of grandparental investment in grandchildren persists despite the grandchildren's adverse early life experiences

Evolutionary theory predicts a downward flow of investment from older to younger generations, representing individual efforts to maximize inclusive fitness. Maternal grandparents and maternal grandmothers (MGMs) in particular consistently show the highest levels of investment (e.g. time, care and resources) in their grandchildren. Grandparental investment overall may depend on social and environmental conditions that affect the development of children and modify the benefits and costs of investment. Currently, the responses of grandparents to adverse early life experiences (AELEs) in their grandchildren are assessed from a perspective of increased investment to meet increased need. Here, we formulate an alternative prediction that AELEs may be associated with reduced grandparental investment, as they can reduce the reproductive value of the grandchildren. Moreover, we predicted that paternal grandparents react more strongly to AELEs compared to maternal grandparents because maternal kin should expend extra effort to invest in their descendants. Using population-based survey data for English and Welsh adolescents, we found evidence that the investment of maternal grandparents (MGMs in particular) in their grandchildren was unrelated to the grandchildren's AELEs, while paternal grandparents invested less in grandchildren who had experienced more AELEs. These findings seemed robust to measurement errors in AELEs and confounding due to omitted shared causes.

Children are important too: juvenile playgroups and maternal childcare in a foraging population, the Agta

Non-maternal carers (allomothers) are hypothesized to lighten the mother's workload, allowing for the specialized human life history including relatively short interbirth intervals and multiple dependent offspring. Here, using in-depth observational data on childcare provided to 78 Agta children (a foraging population in the northern Philippines; aged 0-6 years), we explore whether allomaternal childcare substitutes and decreases maternal childcare. We found that allomother caregiving was associated with reduced maternal childcare, but the substitutive effect varied depending on the source and type of care. Children-only playgroups consistently predicted a decrease in maternal childcare. While grandmothers were rarely available, their presence was negatively associated with maternal presence and childcare, and grandmothers performed similar childcare activities to mothers. These results underscore the importance of allomothering in reducing maternal childcare in the Agta. Our findings suggest that flexibility in childcare sources, including children-only playgroups, may have been the key to human life-history evolution. Overall, our results reinforce the necessity of a broad conceptualization of social support in human childcare. This article is part of the theme issue 'Multidisciplinary perspectives on social support and maternal-child health'.

Does maternal grandmother's support improve maternal and child nutritional health outcomes? Evidence from Merida, Yucatan, Mexico

In humans, high levels of investment are required to raise offspring, because of the prolonged developmental period and short interbirth intervals. The costs borne by individual mothers may be mitigated by obtaining social support from others. This strategy could be particularly valuable for first-time mothers, who lack first-hand experience and whose offspring have higher mortality risk than later-born siblings. As raising children is potentially stressful, mothers may gain from others sharing their experience, providing knowledge/information and emotional support. Being genetically related to both mother and grandchild, maternal grandmothers may be especially well placed to provide such support, while also gaining fitness benefits. We tested the over-arching hypothesis that first-time mothers and their young children supported by the maternal grandmother would have lower levels of stress and better health outcomes, compared to mother-infant dyads lacking such grandmaternal support. A cohort of 90 mother-infant dyads (52 with grandmaternal support, 38 without) was recruited in Merida, Mexico. We assessed anthropometry and body composition in both mother and child, along with maternally perceived stress and child temperament, and documented maternal social relationships. No differences were found in perceived stress/temperament or anthropometry of either mothers or children, according to the presence/absence of grandmaternal support. However, a composite score of whether grandmothers provided advice on infant feeding was positively associated with child nutritional status. Mothers without grandmaternal support reported seeking more informational and emotional support from other female relatives for childcare, potentially compensating for limited/absent grandmaternal support. Our findings may help develop interventions to improve maternal and child health by targeting the dynamics of maternal social networks. This article is part of the theme issue 'Multidisciplinary perspectives on social support and maternal-child health'.

A bioecocultural approach to supporting adolescent mothers and their young children in conflict-affected contexts

An estimated 12 million girls aged 15-19 years, and 777,000 girls younger than 15 give birth globally each year. Contexts of war and displacement increase the likelihood of early marriage and childbearing. Given the developmentally sensitive periods of early childhood and adolescence, adolescent motherhood in conflict-affected contexts may put a family at risk intergenerationally. We propose that the specifics of normative neuroendocrine development during adolescence, including increased sensitivity to stress, pose additional risks to adolescent girls and their young children in the face of war and displacement, with potential lifelong consequences for health and development. This paper proposes a developmental, dual-generational framework for research and policies to better understand and address the needs of adolescent mothers and their small children. We draw from the literature on developmental stress physiology, adolescent parenthood in contexts of war and displacement internationally, and developmental cultural neurobiology. We also identify culturally meaningful sources of resilience and provide a review of the existing literature on interventions supporting adolescent mothers and their offspring. We aim to honor Edward Zigler's groundbreaking life and career by integrating basic developmental science with applied intervention and policy.

Maternal Grandmothers' Household Residency, Children's Growth, and Body Composition Are Not Related in Urban Maya Families from Yucatan

This study analyzes the influence of grandmothers' household residency on the presence of low height-for-age and excessive fat (FMI = fat mass [kg]/height [m²]), waist circumference, and sum of triceps and subscapular skinfolds in a sample of 247 6- to 8-year-old urban Maya children from Yucatan, Mexico. Between September 2011 and January 2014, we obtained anthropometric and body composition data from children and mothers, as well as socioeconomic characteristics of participants and households. Grandmothers' place of residence was categorized as either in the same household as their grandchildren (n = 71) or in separate households (n = 176). Multiple logistic regression models were used to analyze the association between grandmothers' residency and outcome variables. Models were adjusted for maternal anthropometric characteristics and the following socioeconomic variables: family size, location, maternal education, monthly family income, and household crowding. Models showed that the presence of grandmothers in their grandchildren's households was not associated with any of the outcome variables. In contrast, larger family size, overcrowding in the household, and lower family income predicted low height-for-age in children. Larger family size decreased the risk for being overweight based on the three parameters of body composition. Overcrowding in the household increased the risk for greater skinfolds thickness, while low family income increased the risk for higher fat mass index. The residency of grandmothers in their adult daughters' households is not significantly associated with the outcome variables in this sample of urban Maya families. Instead, maternal anthropometric characteristics and socioeconomic conditions of the family have a greater influence on the overall growth of children.

Non-Parental Investment in Children and Child Outcomes after Parental Death or Divorce in a Patrilocal Society

Children rely on support from parental helpers (alloparents), perhaps especially in high-needs contexts. Considerable evidence indicates that closer relatives and maternal relatives are the most likely to provide this care, as inclusive fitness theory suggests, but whether this is equally true across different family types and in culturally patrilocal societies requires investigation. This structured interview study (N = 208 respondents with 323 dependent children) focuses on who helps raise children in rural Bangladesh after the father’s or mother’s death, or divorce, in comparison to families with both parents present or the father temporarily a migrant laborer. Family types differed in where and with whom children resided, who served as their primary and secondary caregivers, and who provided material support, but mother’s kin played a major role, and were the primary providers of material resources from outside the child’s household in all family types. Despite the patrilineal ideology, only one-quarter of children of divorce lived with the father or his family, and even after the death of the mother, only 59% remained with father or other paternal kin. Household income varied by family type and was a strong predictor of child height and weight. The children of deceased mothers moved between successive caregivers especially frequently, and were uniquely likely to have no schooling. The typology of Bangladeshi society as patrilocal obscures the extent to which matrilateral family support children’s well-being.

Offspring fertility and grandchild survival enhanced by maternal grandmothers in a pre-industrial human society

Help is directed towards kin in many cooperative species, but its nature and intensity can vary by context. Humans are one of few species in which grandmothers invest in grandchildren, and this may have served as an important driver of our unusual life history. But helping behaviour is hardly uniform, and insight into the importance of grandmothering in human evolution depends on understanding the contextual expression of helping benefits. Here, we use an eighteenth-nineteenth century pre-industrial genealogical dataset from Finland to investigate whether maternal or paternal grandmother presence (lineage relative to focal individuals) differentially affects two key fitness outcomes of descendants: fertility and survival. We found grandmother presence shortened spacing between births, particularly at younger mother ages and earlier birth orders. Maternal grandmother presence increased the likelihood of focal grandchild survival, regardless of whether grandmothers had grandchildren only through daughters, sons, or both. In contrast, paternal grandmother presence was not associated with descendants' fertility or survival. We discuss these results in terms of current hypotheses for lineage differences in helping outcomes.

Life history and socioecology of infancy

OBJECTIVES

Evolution of human maternal investment strategies is hypothesized to be tied to biological constraints and environmental cues. It is likely, however, that the socioecological context in which mothers' decisions are made is equally important. Yet, a lack of studies examining maternal investment from a cross-cultural, holistic approach has hindered our ability to investigate the evolution of maternal investment strategies. Here, we take a systems-level approach to study how human life history characteristics, environments, and socioecology influence maternal investment in their children.

MATERIALS AND METHODS

We test how infant age and sex, maternal age, parity, and child loss, and the composition of a child's cooperative breeding network are associated with maternal investment across three small-scale (hunter-gatherer, horticultural, and agropastoral), sub-Saharan populations (N = 212). Naturalistic behavioral observations also enable us to illustrate the breadth and depth of the human cooperative breeding system.

RESULTS

Results indicate that infant age, maternal age and parity, and an infant's cooperative childcare network are significantly associated with maternal investment, controlling for population. We also find that human allomaternal care is conducted by a range of caregivers, occupying different relational, sex, and age categories. Moreover, investment by allomothers is widely distributed.

DISCUSSION

Our findings illustrate the social context in which children are reared in contemporary small-scale populations, and in which they were likely reared throughout our evolutionary history. The diversity of the caregiving network, coupled with life history characteristics, is predictive of maternal investment strategies, demonstrating the importance of cooperation in the evolution of human ontogeny.

The contribution of grandmother involvement to child growth and development: an observational study in rural Pakistan

INTRODUCTION

Early childhood interventions primarily focus on the mother-child relationship, but grandmothers are often critical in childcare in low-resource settings. Prior research is mixed on how grandmother involvement influences child outcomes and there is a paucity of research on grandmother caregiving in low-income and middle-income countries. We examined the role of grandmother involvement on child growth and development in the first 2 years of life cross sectionally and longitudinally in rural Pakistan.

METHODS

We used data from the Bachpan Cohort, a longitudinal birth cohort in rural Pakistan. Maternally reported grandmother involvement in daily instrumental and non-instrumental caregiving was collected at 3 and 12 months. A summed score was created and categorised into non-involved, low and high. Outcomes included 12-month and 24-month child growth, 12-month Bayley Scales of Infant and Toddler Development and 24-month Ages and Stages Questionnaire-Socioemotional. We used multivariable generalised linear models to estimate mean differences (MD) at 12 months (n=727) and 24 months (n=712). Inverse probability weighting was used to account for missingness and sampling.

RESULTS

In our sample, 68% of children lived with a grandmother, and most grandmothers were involved in caregiving. Greater 3-month grandmother involvement was positively associated with 12-month weight z-scores; however, greater involvement was associated with lower 24-month weight z-scores. High 12-month grandmother involvement was associated with improved 12-month cognitive (MD=0.38, 95% CI -0.01 to 0.76), fine motor skills (MD=0.45, 95% CI 0.08 to 0.83) and 24-month socioemotional development (MD=-17.83, 95% CI -31.47 to -4.19). No meaningful associations were found for length z-scores or language development.

CONCLUSION

In rural Pakistan, grandmothers provide caregiving that influences early child development. Our findings highlight the complex relationship between grandmother involvement and child weight, and suggest that grandmothers may positively promote early child cognitive, fine motor and socioemotional development. Understanding how grandmother involvement affects child outcomes in early life is necessary to inform caregiving interventions.

Hired helpers at the nest: The association between life-cycle servants and net fertility in North Orkney, 1851-1911

OBJECTIVES

The presence of kin is often, but not always, associated with higher fertility in historical populations. However, the effect of other household members on fertility is less frequently studied. While not genetically related, life-cycle servants lived and worked alongside household members and may have provided assistance to reproducing families. Female servants in particular may have helped mothers with small children through direct help with childcare activities or by replacing the economic effort of mothers whose work was not compatible with childcare. This study examines the presence of servants in the households of married women of reproductive age to assess whether households with young children are more likely to also have servants.

MATERIALS AND METHODS

This study uses individual-level census data from North Orkney, Scotland (1851-1911) to investigate the relationship between the presence of servants in households and a measure of recent net marital fertility, the number of women's own-children under age 5, using logistic regression models.

RESULTS

Households with young children were more likely to have a female, but not male, servant in the household after controlling for the effects of other possible helpers, including older children, mothers, and mothers-in-law.

DISCUSSION

These findings are consistent with prior research that indicates the importance of female labor to smallholder agricultural households and suggests that female servants may have provided support to reproducing families. Life-cycle servants should be considered one component of biocultural reproduction in historical Northwest Europe. The use of hired help is not restricted to contemporary or elite groups.

How do grandparents influence child health and development? A systematic review

Grandparents are often a key source of care provision for their grandchildren, yet they are sidelined in caregiving research and policy decisions. We conducted a global, systematic review of the literature to examine the scope and quality of studies to date (PROSPERO database CRD42019133894). We screened 12,699 abstracts across 7 databases, and identified 206 studies that examined how grandparents influence child health and development. Indicators of grandparent involvement were contact, caregiving behaviors, and financial support. Our review focused on two research questions: how do grandparents influence child health and development outcomes, and what range of child outcomes is reported globally? We examined study design, sample characteristics, key findings, and outcomes pertaining to grandchildren's physical health, socio-emotional and behavioral health, and cognitive and educational development.  Our search captured studies featuring grandparent custodial care (n = 35), multigenerational care (n = 154), and both types of care (n = 17). We found substantial heterogeneity in the data provided on co-residence, caregiving roles, resources invested, outcomes, and mechanisms through which "grandparent effects" are manifested. We identified two important issues, related to operationalizing indicators of grandparent involvement and conceptualizing potential mechanisms, leading to gaps in the evidence base. Currently, our understanding of the pathways through which grandparents exert their influence is constrained by limited data on what grandparents actually do and insufficient attention given to interpersonal and structural contexts. We present a conceptual framework to explicitly measure and theorize pathways of care, with a view to inform research design and policy implementation. We underscore the need for more robust data on three indicators of caregiver involvement-contact, behavior, and support-and for careful description of structural and interpersonal contexts in caregiving research.

Family networks and infant health promotion: a mixed-methods evaluation from a cluster randomised controlled trial in rural Malawi

OBJECTIVE

Parents may rely on information provided by extended family members when making decisions concerning the health of their children. We evaluate whether extended family members affected the success of an information intervention promoting infant health.

METHODS

This is a secondary, sequential mixed-methods study based on a cluster randomised controlled trial of a peer-led home-education intervention conducted in Mchinji District, Malawi. We used linear multivariate regression to test whether the intervention impact on child height-for-age z-scores (HAZ) was influenced by extended family members. 12 of 24 clusters were assigned to the intervention, in which all pregnant women and new mothers were eligible to receive 5 home visits from a trained peer counsellor to discuss infant care and nutrition. We conducted focus group discussions with mothers, grandmothers and peer counsellors, and key-informant interviews with husbands, chiefs and community health workers to better understand the roles of extended family members in infant feeding.

RESULTS

Exposure to the intervention increased child HAZ scores by 0.296 SD (95% CI 0.116 to 0.484). However, this effect is smaller in the presence of paternal grandmothers. Compared with an effect size of 0.441 to 0.467 SD (95% CI -0.344 to 1.050) if neither grandmother is alive, the effect size was 0.235 (95% CI -0.493 to 0.039) to 0.253 (95% CI -0.529 to 0.029) SD lower if the paternal grandmother was alive. There was no evidence of an effect of parents' siblings. Maternal grandmothers did not affect intervention impact, but were associated with a lower HAZ score in the control group. Qualitative analysis suggested that grandmothers, who act as secondary caregivers and provide resources for infants, were slower to dismiss traditionally held practices and adopt intervention messages.

CONCLUSION

The results indicate that the intervention impacts are diminished by paternal grandmothers. Intervention success could be increased by integrating senior women.

When the mother-in-law is just as good-Differential mortality of reproductive females by family network composition

Motivated by the cooperative breeding hypothesis, we investigate the effect of having kin on the mortality of reproductive women based on family reconstitutions for the Krummhörn region (East Frisia, Germany, 1720-1874). We rely on a combination of Cox clustered hazard models and hazard models stratified at the family level. In order to study behavior-related effects, we run a series of models in which only kin who lived in the same parish are considered. To investigate structural, non-behavior-related effects, we run a different model series that include all living kin, regardless their spatial proximity. We find that women of reproductive age who had a living mother had a reduced mortality risk. It appears that having living sisters had an ambivalent impact on women's mortality: i.e., depending on the socioeconomic status of the family, the effect of having living sisters ranged between representing a source of competition and representing a source of support. Models which are clustered at the family level suggest that the presence of a living mother-in-law was associated with reduced mortality among her daughters-in-law especially among larger-scale farm families. We interpret this finding as a consequence of augmented consanguineous marriages among individuals of higher social strata. For instance, in first cousin marriages, the mother-in-law could also be a biological aunt. Thus, it appears that among the wealthy elite, the genetic in-law conflict was neutralized to some extent by family solidarity. This result further suggests that the tipping point of the female trade-off between staying with the natal family and leaving the natal family to join an economically well-established in-law family might have been reached very quickly among women living under the socioeconomic conditions of the Krummhörn region.