The effects of kin on child mortality in rural Gambia

Survival among children under-five in India: a parametric multilevel survival approach

BACKGROUND

Many studies have been conducted on under-five mortality in India and most of them focused on the associations between individual-level factors and under-five mortality risks. On the contrary, only a scarce number of literatures talked about contextual level effect on under-five mortality. Hence, it is very important to have thorough study of under-five mortality at various levels. This can be done by applying multilevel analysis, a method that assesses both fixed and random effects in a single model. The multilevel analysis allows extracting the influence of individual and community characteristics on under-five mortality. Hence, this study would contribute substantially in understanding the under-five mortality from a different perspective.

METHOD

The study used data from the Demographic and Health Survey (DHS) acquired in India, i.e., the fourth round of National Family and Health Survey (2015-16). It is a nationally representative repeated cross-sectional data. Multilevel Parametric Survival Model (MPSM) was employed to assess the influence of contextual correlates on the outcome. The assumption behind this study is that 'individuals' (i.e., level-1) are nested within 'districts' (i.e., level-2), and districts are enclosed within 'states' (i.e., level-3). This suggests that people have varying health conditions, residing in dissimilar communities with different characteristics.

RESULTS

Highest under-five mortality i.e., 3.85% are happening among those women whose birth interval is less than two years. In case of parity, around 4% under-five mortality is among women with Third and above order parity. Further, findings from the full model is that ICC values of 1.17 and 0.65% are the correlation of the likelihood of having under-five mortality risk among people residing in the state and district communities, respectively. Besides, the risk of dying was increased alarmingly in the first year of life and slowly to aged 3 years and then it remains steady.

CONCLUSION

This study has revealed that both aspects viz. individual and contextual effect of the community are necessary to address the importance variations in under-five mortality in India. In order to ensure substantial reduction in under-five mortality, findings of the study support some policy initiatives that involves the need to think beyond individual level effects and considering contextual characteristics.

From the Ground Up: A Multidisciplinary Approach to Past Fertility and Population Narratives

Population dynamics form a crucial component of human narratives in the past. Population responses and adaptations not only tell us about the human past but also offer insights into the present and future. Though an area of substantial interest, it is also one of often limited evidence. As such, traditional techniques from demography and anthropology must be adapted considerably to accommodate the available archaeological and ethnohistoric data and an appropriate inferential framework must be applied. In this article, I propose a ground-up, multidisciplinary approach to the study of past population dynamics. Specifically, I develop an empirically informed path diagram based on modern fertility interactions and sources of past environmental, sociocultural, and biological evidence to guide high-resolution case studies. The proposed approach is dynamic and can evolve in response to data inputs as case studies are undertaken. In application, this approach will create new knowledge of past population processes which can greatly enhance our presently limited knowledge of high-frequency, small-scale demographic fluctuations, as well as contribute to our broader understanding of significant population disturbances and change throughout human history.

Household structure, composition and child mortality in the unfolding antiretroviral therapy era in rural South Africa: comparative evidence from population surveillance, 2000-2015

OBJECTIVES

The structure and composition of the household has important influences on child mortality. However, little is known about these factors in HIV-endemic areas and how associations may change with the introduction and widespread availability of antiretroviral treatment (ART). We use comparative, longitudinal data from two demographic surveillance sites in rural South Africa (2000-2015) on mortality of children younger than 5 years (n=101 105).

DESIGN

We use multilevel discrete time event history analysis to estimate children's probability of dying by their matrilineal residential arrangements. We also test if associations have changed over time with ART availability.

SETTING

Rural South Africa.

PARTICIPANTS

Children younger than 5 years (n=101 105).

RESULTS

3603 children died between 2000 and 2015. Mortality risks differed by co-residence patterns along with different types of kin present in the household. Children in nuclear households with both parents had the lowest risk of dying compared with all other household types. Associations with kin and child mortality were moderated by parental status. Having older siblings lowered the probability of dying only for children in a household with both parents (relative risk ratio (RRR)=0.736, 95% CI (0.633 to 0.855)). Only in the later ART period was there evidence that older adult kin lowered the probability of dying for children in single parent households (RRR=0.753, 95% CI (0.664 to 0.853)).

CONCLUSIONS

Our findings provide comparative evidence of how differential household profiles may place children at higher mortality risk. Formative research is needed to understand the role of other household kin in promoting child well-being, particularly in one-parent households that are increasingly prevalent.

The relationship between extended kin resources and children's healthcare utilization: An analysis of family networks

Extended kin serve as key sources of financial, social, and instrumental support for young children and their families. In impoverished settings, the ability to rely on extended kin for investments, information, and/or in-kind support to access health care when needed may be particularly important in buffering children against poor health outcomes and mortality. Given data limitations, little is known about how specific social and economic characteristics of extended kin shape children's healthcare access and health outcomes. We use detailed household survey data from rural Mali, where related households co-reside in extended family compounds, a living arrangement typical across West Africa and other settings globally. We examine how specific social and economic characteristics of extended kin residing in close geographic proximity affect children's healthcare utilization in a sample of 3948 children under five years of age reporting illness in the preceding two weeks. Absolute wealth among extended family networks is associated with utilization of any healthcare and healthcare with a formally-trained provider, an indicator of health service quality (adjusted odds ratio (aOR) = 1.29, 95% CI 1.03, 1.63; aOR = 1.49, 95% CI 1.17, 1.90, respectively). Net of maternal characteristics, educational attainment and decision-making power of extended female relatives of reproductive age in the concession network are powerful predictors of any healthcare utilization (aOR = 1.69, 95% CI 1.18, 2.42; aOR = 1.59, 95% CI 1.27, 1.99, respectively). Labor force participation among extended relatives is not associated with healthcare utilization outcomes among young children, while maternal labor force participation is predictive of utilization of any care and care with a formally-trained provider (aOR = 1.41, 95% CI 1.12, 1.78; aOR = 1.36, 95% CI 1.11, 1.67, respectively). These findings underscore the importance of financial and instrumental support from extended family and illuminate the ways extended families work together to return young children to health in the face of resource constraints.

Female cooperation: evolutionary, cross-cultural and ethnographic evidence

Women and girls cooperate with each other across many domains and at many scales. However, much of this information is buried in the ethnographic record and has been overlooked in theoretic constructions of the evolution of human sociality and cooperation. The assumed primacy of male bonding, hunting, patrilocality and philopatry has dominated the discussion of cooperation without balanced consideration. A closer look at the ethnographic record reveals that in addition to cooperative childcare and food production, women and girls collectively form coalitions, have their own cooperative political, ceremonial, economic and social institutions, and develop female-based exchange and support networks. The numerous ethnographic examples of female cooperation urge reconsideration of gender stereotypes and the limits of female cooperation. This review brings together theoretic, cross-cultural and cross-lifespan research on female cooperation to present a more even and empirically supported view of female sociality. Following the lead from trends in evolutionary biology and sexual selection theory, the hope going forward is that the focus shifts from rote characterizations of sex differences to highlighting sources of variation and conditions that enhance or constrain female cooperative engagement. This article is part of the theme issue 'Cooperation among women: evolutionary and cross-cultural perspectives'.

Girls in early childhood increase food returns of nursing women during subsistence activities of the BaYaka in the Republic of Congo

Nursing mothers face an energetic trade-off between infant care and work. Under pooled energy budgets, this trade-off can be reduced by assistance in food acquisition and infant care tasks from non-maternal carers. Across cultures, children also often provide infant care. Yet the question of who helps nursing mothers during foraging has been understudied, especially the role of children. Using focal follow data from 140 subsistence expeditions by BaYaka women in the Republic of Congo, we investigated how potential support from carers increased mothers' foraging productivity. We found that the number of girls in early childhood (ages 4–7 years) in subsistence groups increased food returns of nursing women with infants (kcal collected per minute). This effect was stronger than that of other adult women, and older girls in middle childhood (ages 8–13 years) and adolescence (ages 14–19 years). Child helpers were not necessarily genetically related to nursing women. Our results suggest that it is young girls who provide infant care while nursing mothers are acquiring food—by holding, monitoring and playing with infants—and, thus, that they also contribute to the energy pool of the community during women's subsistence activities. Our study highlights the critical role of children as carers from early childhood.

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.

Effects of Family Demographics and Household Economics on Sidama Children's Nutritional Status

Weight- (WAZ), height- (HAZ), and BMI-for-age (BMIZ) are frequently used to assess malnutrition among children. These measures represent different categories of risk and are usually hypothesized to be affected by distinct factors, despite their inherent relatedness. Life history theory suggests weight should be sacrificed before height, indicating a demonstrable relationship among them. Here we evaluate impact of family composition and household economics on these measures of nutritional status and explore the role of WAZ as a factor in HAZ. Anthropometrics, family demographics, and measures of household economy were collected from Sidama agropastoralist children in a peri-urban village in southwestern Ethiopia (n = 157; 79 girls). Just over half of the sample (50.9%) had z-scores of - 2SD or below on at least one measure, indicating an elevated risk of morbidity/mortality; 30% were at or below - 2SD on two or more measures. We used hierarchical linear regression with random intercept analysis to model WAZ and HAZ. Siblings and crop sales significantly decrease WAZ while electricity, agriculture, and polygyny improve z-scores; however, an interaction between polygyny and siblings indicates negative effects of siblings in polygynous families and positive effects in nonpolygynous ones (adj. R² = 66.5%). For HAZ, agriculture and electricity are positively associated with z-scores whereas siblings have a negative effect; the interaction term again indicates that effects of siblings vary in polygynous and nonpolygynous families (adj. R² = 74.2%). A mediation model exploring the role of weight in height outcomes suggests not only that WAZ has direct effects on HAZ but also that effects of electricity and agriculture on HAZ are partially mediated by WAZ. Our findings indicate that WAZ and HAZ are primarily affected by shared variables, but effects of siblings vary by polygyny status. Long-term outcomes (HAZ) among Sidama children would likely benefit from interventions focused on stabilizing WAZ across family members.

A Psychometric Evaluation of the Intrasexual Competition Scale

The Intrasexual Competition Scale (ICS) measures the extent to which individuals view their interaction with same-sex others in competitive terms. Although it is frequently used in studies investigating differences in mating behavior, the factor structure of the ICS has never been confirmed. Researchers have yet to use multiple-group confirmatory factor analysis to test whether the properties of the scale are equivalent between the sexes. In Study 1, we report on an investigation in which participants' responses to the ICS were submitted to exploratory factor analysis (EFA). In Study 2A, we compared the fit of one and two-factor models from the EFA as well as two additional models, using confirmatory factor analysis with an independent sample. The best fit was obtained by a two-factor solution, which reflected: (1) respondents' feelings of frustration when intrasexual competitors are better off (Inferiority Frustration), and (2) respondents' enjoyment of being better than intrasexual competitors (Superiority Enjoyment). This model achieved a high degree of measurement invariance. In Study 2B, we found the ICS had good concurrent validity via associations with sociosexuality, mating effort, and sexual behavior. Together, these analyses suggest that the ICS is a valid measure of intrasexually competitive attitudes.

The effects of income fluctuations on undernutrition and overnutrition across the lifecycle

This study uses individual level data from a 13-year, nationally representative rotating panel survey of Kyrgyzstan to estimate the effects of fluctuations in predicted income on health and nutrition outcomes from early childhood to adulthood. We consider impacts on both undernutrition and overnutrition side-by-side, and carefully consider the mechanisms at work. We address the endogeneity of income following Bartik (1991): We construct a measure of predicted income, obtained using the household's initial period share of income from different sources and aggregate national growth rates over time in each source. We find that young children (under age 5) exposed to reductions in predicted income experienced reductions in important measures of health and nutrition: weight, weight-for-age Z-scores, and weight-for-height Z-scores. We further identify reductions in both weight and height among older children (aged 5-18). Declines in child health and nutrition are most pronounced among households most dependent on agriculture and those living in rural areas. Reduced consumption of healthy foods and reduced parental time spent with children may help explain the results. A channel possibly offsetting negative impacts is increased use of contraceptives. At the same time, older children and adults experienced decreases in body mass index and-for adults-decreases in the incidence of overweight and obesity, suggesting selective health benefits for some groups.

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'.

Are fathers a good substitute for mothers? Paternal care and growth rates in Shodagor children

Biparental care is a hallmark of human social organization, though paternal investment varies between and within societies. The facultative nature of paternal care in humans suggests males should invest when their care improves child survival and/or quality, though testing this prediction can be challenging because of the difficulties of empirically isolating paternal effects from those of other caregivers. Additionally, the broader context in which care is provided, vis-à-vis care from mothers and others, may lead to different child outcomes. Here, we examine the effects of paternal care on child growth among Shodagor fisher-traders, where fathers provide high levels of both additive and substitutive care, relative to mothers. We modeled seasonal z-scores and velocities for height, weight, and body mass index (BMI) outcomes using linear mixed models. Our evidence indicates that, as predicted, the context of paternal care is an important predictor of child outcomes. Results show that environmental seasonality and alloparental help contribute to a nuanced understanding of the impact of Shodagor paternal care on child physiology.

Effects of family planning on fertility behaviour across the demographic transition

The adoption of contraception often coincides with market integration and has transformative effects on fertility behavior. Yet many parents in small-scale societies make decisions about whether and when to adopt family planning in an environment where the payoffs to  have smaller families are uncertain. Here we track the fertility of Maya women across 90 years, spanning the transition from natural to contracepting fertility. We first situate the uncertainty in which fertility decisions are made and model how childbearing behaviors respond. We find that contraception, a key factor in cultural transmission models of fertility decline, initially has little effect on family size as women appear to hedge their bets and adopt fertility control only at the end of their reproductive careers. Family planning is, however, associated with the spread of lower fertility in later cohorts. Distinguishing influences on the origin versus spread of a behaviour provides valuable insight into causal factors shaping individual and normative changes in fertility.

"We All Join Hands": Perceptions of the Kangaroo Method Among Female Relatives of Newborns in The Gambia

Family support is essential for kangaroo mother care (KMC), but there is limited research regarding perceptions of female relatives, and none published from West African contexts. In-depth interviews were conducted from July to August 2017 with a purposive sample of 11 female relatives of preterm neonates admitted to The Gambia's referral hospital. Data were coded in NVivo 11, and thematic analysis was conducted applying an inductive framework. Female relatives were willing to support mothers by providing KMC and assisting with domestic chores and agricultural labor. Three themes were identified: (a) collective family responsibility for newborn care, with elder relatives being key decision makers, (b) balance between maintaining traditional practices and acceptance of KMC as a medical innovation, and (c) gendered expectations of women's responsibilities postnatally. Female relatives are influential stakeholders and could play important roles in KMC programs, encourage community ownership, and contribute to improved outcomes for vulnerable newborns.

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.

On age-specific selection and extensive lifespan beyond menopause

Standard evolutionary theory of ageing predicts weaker purifying selection on genes critical to later life stages. Prolonged post-reproductive lifespan (PPRLS), observed only in a few species like humans, is likely a result of disparate relaxation of purifying selection on survival and reproduction in late life stages. While the exact origin of PPRLS is under debate, many researchers agree on hypotheses like mother-care and grandmother-care, which ascribe PPRLS to investment into future generations-provision to one's descendants to enhance their overall reproductive success. Here, we simulate an agent-based model, which properly accounts for age-specific selection, to examine how different investment strategies affect the strength of purifying selection on survival and reproduction. We observed in the simulations that investment strategies that allow a female individual to remain contributive to its own descendants (infants and adults) at late life stages may lead to differential relaxation of selection on survival and reproduction, and incur the adaptive evolution of PPRLS.

Household composition and child health in Botswana

Background

There is a general lack of research on children’s household experiences and child health outcomes in low- and middle-income countries (LMICs). This study examines the relationship between household composition, stunting and diarrhoea prevalence among children younger than 5 years of age in Botswana.

Methods

The analysis uses data from the 2007 Botswana Family Health Survey (BFHS) and multilevel logistic regression models.

Results

The findings indicate that stunting varies by whom the child lives with. Stunting is higher among children living with no parents compared to those living with both parents. Stunting is also high among children living with unrelated household members. Similarly, children in households with a mother-only and with a grandparent present, have a higher level of stunting compared to those living with both parents. Conversely, living with an aunt and living with other relatives, protects against stunting. The findings on diarrhoea prevalence show that children living in mother-only households and those living with no parents are less likely to have diarrhoea than those living with both parents. Also, across all households, those who are more affluent have lower rates of child stunting and diarrhoea than those which are more deprived. Finally, the findings show a clustering effect at the household level for both stunting and diarrhoea prevalence.

Conclusions

These findings suggest that policies and programs aimed at reducing stunting and diarrhoea may work best if they target households and other adults co-residing in homes with children besides biological parents. Further, children who live in poorer households deserve special attention.

Risk of childhood mortality associated with death of a mother in low-and-middle-income countries: a systematic review and meta-analysis

Background

Death of a mother at an early age of the child may result in an increased risk of childhood mortality, especially in low-and-middle-income countries. This study aims to synthesize estimates of the association between a mother’s death and the risk of childhood mortality at different age ranges from birth to 18 years in these settings.

Methods

Various MEDLINE databases, EMBASE, and Global Health databases were searched for population-based cohort and case-control studies published from 1980 to 2017. Studies were included if they reported the risk of childhood mortality for children whose mother had died relative to those whose mothers were alive. Random-effects meta-analyses were used to pool effect estimates, stratified by various exposures (child’s age when mother died, time since mother’s death) and outcomes (child’s age at risk of child death).

Results

A total of 62 stratified risk estimates were extracted from 12 original studies. Childhood mortality was associated with child’s age at time of death of a mother and time since a mother’s death. For children whose mother died when they were ≤ 42 days, the relative risk (RR) of dying within the first 1–6 months of the child’s life was 35.5(95%CI:9.7–130.5, p [het] = 0.05) compared to children whose mother did not die; by 6–12 months this risk dropped to 2.8(95%CI:0.7–10.7). For children whose mother died when they were ≤ 1 year, the subsequent RR of dying in that year was 15.9(95%CI:2.2–116.1,p [het] = 0.02), compared to children whose mother lived. For children whose mother died when they were ≤ 5 years of age, the RR of dying before aged 12 was 4.1(95%CI:3.0–5.7),p [het] = 0.83. Mortality was also elevated in specific analysis  among children whose mother died when child was older than 42 days. Overall, for children whose mother died < 6 and 6+ months ago, RRs of dying before reaching adulthood (≤18 years) were 4.7(95%CI:2.6–8.7,p [het] = 0.2) and 2.1(95%CI:1.3–3.4,p [het] = 0.7), respectively, compared to children whose mother lived.

Conclusions

There is evidence of an association between the death of a mother and childhood mortality in lower resource settings. These findings emphasize the critical importance of women in family outcomes and the importance of health care for women during the intrapartum and postpartum periods and throughout their child rearing years.

Electronic supplementary material

The online version of this article (10.1186/s12889-019-7316-x) contains supplementary material, which is available to authorized users.

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.

A Cohort Perspective on the Demography of Grandparenthood: Past, Present, and Future Changes in Race and Sex Disparities in the United States

How has the demography of grandparenthood changed over the last century? How have racial inequalities in grandparenthood changed, and how are they expected to change in the future? Massive improvements in mortality, increasing childlessness, and fertility postponement have profoundly altered the likelihood that people become grandparents as well as the timing and length of grandparenthood for those that do. The demography of grandparenthood is important to understand for those taking a multigenerational perspective of stratification and racial inequality because these processes define the onset and duration of intergenerational relationships in ways that constrain the forms and levels of intergenerational transfers that can occur within them. In this article, we discuss four measures of the demography of grandparenthood and use simulated data to estimate the broad contours of historical changes in the demography of grandparenthood in the United States for the 1880-1960 birth cohorts. Then we examine race and sex differences in grandparenthood in the past and present, which reveal declining inequality in the demography of grandparenthood and a projection of increasing group convergence in the coming decades.

Does it Take a Village? Kin Coresidence and Child Survival in Tanzania

Children in Tanzania live in a variety of family structures, many of which contain related and unrelated non-parental adults. In this article, I use data from the Rufiji Health and Demographic Surveillance System in Tanzania to examine the role of coresident non-parental adults in childrearing. First, I use quantitative demographic data to investigate the association between kin coresidence and child survival, differentiating by lineage. I also examine the role of unrelated coresident adults. Second, I test whether coresident non-parental adults moderate the association between parental absence and child survival. Finally, I draw from qualitative interview data to investigate childrearing practices and beliefs, with a particular focus on parental absence and kin coresidence. I find that, despite the institutionalization of kin caregiving, coresidence with kin is not beneficial, and kin are unable to compensate for parental absence. The two-parent living arrangement is viewed as ideal, although the reality of childrearing in the setting is complex and fluid. While absent parents try to maintain support of their children, such assistance is insufficient in times of health crisis. Kin care for children with absent parents, but their willingness to assist depends on the reason for the absence.

Is the timing of menarche correlated with mortality and fertility rates?

Timing of menarche has largely been studied in the context of a secular trend. However, since mortality and fertility rates are fundamental demographic factors linked to a population’s developmental and reproductive characteristics, we expect that the timing of menarche, a precondition to reproduction, is also associated with these vital rates. We conduct an analysis of 89 countries and 21 demographic, socioeconomic, nutritional, and educational variables selected for their known influence on menarche. Model results predict that a country’s fertility and adult female mortality rates are significant predictors of mean age at menarche, while other covariates are not. Specifically, menarche is delayed in countries with high mortality and high fertility, which may be proxies for assessing overall environmental quality. We emphasize that, for a comprehensive understanding of the timing of menarche, it is critical to take into account both individual- and population-level influences.

Infant handling by female mountain gorillas: Establishing its frequency, function, and (ir)relevance for life history evolution

OBJECTIVES

Infant handling describes cases in which youngsters are temporarily removed from the care of their mothers and "taken care of" (held, carried, etc.) by other conspecifics. Handlers may gain indirect fitness benefits from these actions and can practice mothering skills, thereby improving the odds of survival of their own infants. Great apes are notable for displaying little infant handling. Apart from anecdotal observations, no published data exist on infant handling in wild mountain gorillas. We tested two of the most pertinent explanations ("kin selection" and "learning to mother") in a wild population of mountain gorillas in Rwanda. We predicted that (a) nulliparous females would exhibit infant handling (i.e., carrying) more than parous females and (b) maternal kin would exhibit more infant handling than nonkin.

METHODS

We collated 8 years of data on infant carrying behavior collected in 13 groups monitored by the Dian Fossey Gorilla Fund's Karisoke Research Center.

RESULTS

Infant handling is an infrequent behavior (1,783 instances over 25,600 observation hours). A strong positive effect of relatedness and handler parity on the frequency of infant handling emerged.

CONCLUSIONS

While the nature of handler-infant interactions (affiliative, abusive, etc.) remains unstudied, they could constitute alloparental care and could therefore attenuate maternal energetic burden and ultimately allow increased birth rates. However, the rarity of this behavior makes it an unlikely contributor to mountain gorillas' relatively short interbirth intervals.

The influence of unpredictable, fragmented parental signals on the developing brain

Mental illnesses originate early in life, governed by environmental and genetic factors. Because parents are a dominant source of signals to the developing child, parental signals - beginning with maternal signals in utero - are primary contributors to children's mental health. Existing literature on maternal signals has focused almost exclusively on their quality and valence (e.g. maternal depression, sensitivity). Here we identify a novel dimension of maternal signals: their patterns and especially their predictability/unpredictability, as an important determinant of children's neurodevelopment. We find that unpredictable maternal mood and behavior presage risk for child and adolescent psychopathology. In experimental models, fragmented/unpredictable maternal care patterns directly induce aberrant synaptic connectivity and disturbed maturation of cognitive and emotional brain circuits, with commensurate memory problems and anhedonia-like behaviors. Together, our findings across species demonstrate that patterns of maternal signals influence brain circuit maturation, promoting resilience or vulnerability to mental illness.

Kin support and child health: Investigating two approaches in an African slum

Extensive research from sub-Saharan Africa shows that mothers frequently rely on help from other family members to ensure their children's health and well-being. Yet, there is considerable debate about the relative importance of support from grandmothers versus fathers. Using an innovative survey instrument to interview 462 unmarried mothers in a slum area of Nairobi, Kenya, we provide insight into this debate by showing that a status versus transfers approach to measuring kin support asks subtly different questions and yields different results. A status approach reflects an evolutionary perspective that argues that maternal grandmothers have a greater incentive than non-residential fathers to provide material and practical support for young children. In contrast, a transfers approach is consistent with social support theories whereby the social capital provided by fathers may be more beneficial to children's health than that afforded by grandmothers. Demonstrating that different approaches to measuring kin support matter highlights the need for kin research that crosses disciplinary boundaries and encourages the development of more nuanced family policies designed to protect children's health in Africa.

Aging is an adaptation that selects in animals against disruption of homeostasis

During evolution, Muller's ratchet permanently generates deleterious germline mutations that eventually must be defused by selection. It seems widely held that cancer and aging-related diseases (ARDs) cannot contribute to this germline gene selection because they tail reproduction and thus occur too late, at the end of the life cycle. Here we posit however that by lessening the offspring's survival by proxy through diminishing parental care, they can still contribute to the selection. The hypothesis in detail: The widespread occurrence of aging in animals suggests that it is an adaptation. But to what benefit? Aging seems to have only drawbacks. In humans, ARDs cause today almost all mortality; they include heart disease, cerebrovascular disease, Alzheimer's disease, kidney disease and cancer. Compensation seems unthinkable. For cancer, the author proposed in a previous study a benefit to the species: purifying selection against deleterious germline genes that when expressed enhance intracellular energy dissipation. This multicausal energy dissipation, posited as the universal origin of cancer initiation, relates to cellular heat generation, disrupted metabolism, and inflammation. The organism reproduces during cancer's dormancy, and when approaching its end of life, the onset of cancer is accelerated in proportion to the cancer-initiating signal. Through cancer, the organism, now a parent, implements the self-actuated programmed death of Skulachev's phenoptosis. This "first death" enhances by proxy the offspring's chance of "second death" (or "double death") through diminished parental care. Repetition over generations realizes a purifying selection against genes causing energy dissipation. The removal of the deleterious germline gene mutations permanently generated by Muller's ratchet gives a benefit. We generalize, motivated by the parallels between cancer and aging, the purifying selection posited for cancer to aging. An ARD would be initiated in the organ by multicausal disruption of homeostasis, and be followed by dormancy and senescence until its onset near the end of the life cycle. Just as for cancer, the ARD eventually enhances double death, and the realized permanent selection gives a benefit to the species through the selection against germ line genes that disrupt homeostasis. Given their similarities, cancer and aging are combined in the posited Unified Cancer-Aging Adaptation (UCAA) model, which may be confirmed by next-generation sequencing data. Also because of the emerging important role of cellular senescence, the hypothesis may guide the development of therapies against both cancer and aging.

Early-life mortality clustering in families: A literature review

Research on early-life mortality in contemporary and historical populations has shown that infant and child mortality tend to cluster in a limited number of high-mortality families, a phenomenon known as 'mortality clustering'. This paper is the first to review the literature on the role of the family in early-life mortality. Contemporary results, methodological and theoretical shortfalls, recent developments, and opportunities for future research are all discussed in this review. Four methodological approaches are distinguished: those based on sibling deaths, mother heterogeneity, thresholds, and excess deaths in populations. It has become clear from research to date that the death of an older child harms the survival chances of younger children in that family, and that fertility behaviour, earlier stillbirths, remarriages, and socio-economic status all explain mortality clustering to some extent.

Determinants of neonatal, infant and under-five mortality in a war-affected country: analysis of the 2010 Household Health Survey in South Sudan

Background

Under-five children born in a fragile and war-affected setting of South Sudan are faced with a high risk of death as reflecting in high under-five mortality. In South Sudan health inequities and inequitable condition of daily living play a significant role in childhood mortality. This study examines factors associated with under-five mortality in South Sudan.

Methods

The study population includes 8125 singleton, live birth, under-five children born in South Sudan within 5 years prior to the 2010 South Sudan Household Survey. Factors associated with neonatal, infant and under-five deaths were examined using generalised linear latent and mixed models with the logit link and binomial family that adjusted for cluster and survey weights.

Results

The multivariate analysis showed that mothers who reported a previous death of a child reported significantly higher risk of neonatal (adjusted OR (AOR)=3.74, 95% confidence interval (CI 2.88 to 4.87), P<0.001), infant (AOR=3.19, 95% CI (2.62 to 3.88), P<0.001) and under-five deaths (AOR=3.07, 95% CI (2.58 to 3.64), P<0.001). Other associated factors included urban dwellers (AOR=1.37, 95% CI (1.01 to 1.87), P=0.045) for neonatal, (AOR=1.35, 95% CI (1.08 to 1.69), P=0.009) for infants and (AOR=1.39, 95% CI (1.13 to 1.71), P=0.002) for under-five death. Unimproved sources of drinking water were significantly associated with neonatal mortality (AOR=1.91, 95% CI (1.11 to 3.31), P=0.02).

Conclusions

This study suggested that the condition and circumstances in which the child is born into, and lives with, play a role in under-five mortality, such as higher mortality among children born to teenage mothers. Ensuring equitable healthcare service delivery to all disadvantaged populations of children in both urban and rural areas is essential but remains a challenge, while violence continues in South Sudan.

Limited support for the X-linked grandmother hypothesis in pre-industrial Finland

The level of kin help often depends on the degree of relatedness between a helper and the helped. In humans, grandmother help is known to increase the survival of grandchildren, though this benefit can differ between maternal grandmothers (MGMs) and paternal grandmothers (PGMs) and between grandsons and granddaughters. The X-linked grandmother hypothesis posits that differential X-chromosome relatedness between grandmothers and their grandchildren is a leading driver of differential grandchild survival between grandmother lineages and grandchild sexes. We tested this hypothesis using time-event models on a large, multigenerational dataset from pre-industrial Finland. We found that the presence of an MGM increases grandson survival more than PGM presence, and that granddaughter survival is higher than that of grandsons in the presence of a PGM. However, there was no support for the key prediction that the presence of PGMs improves granddaughter survival more than that of MGMs, diminishing the overall support for the hypothesis. Our results call for alternative explanations for differences in the effects of maternal and paternal kin to grandchild survival in humans.

Beyond Orphanhood: Parental Nonresidence and Child Well-being in Tanzania

This article used data from the Rufiji Health and Demographic Surveillance System in Tanzania to examine the influence of parental non-residence on child survival and school entry. Using survival analysis methods, the article tested variations by parent and by cause, examining parental death, non-residence due to parental relationship status, and migration. In general, maternal non-residence was more consequential for child survival, while paternal non-residence influences school entry. This is consistent with gendered parenting patterns in the setting. There was important variation by cause and by outcome, particularly for paternal non-residence. Paternal non-residence due to non-marital birth was associated with increased risk of child death, while paternal migration was associated with improved survival. Paternal death and migration were associated with lower odds of school entry. This article moves beyond orphanhood to consider multiple causes of parental non-residence simultaneously, demonstrating that parental non-residence is not uniformly deleterious for children.

Who Helps Single Mothers in Nairobi? The Role of Kin Support

Single mothers often turn to their extended kin for financial assistance and to help with child care. Such support may be especially important in areas of high poverty and poor environmental conditions. Using novel kinship data, this paper assesses the extent of support given by over 3,000 relatives to 462 single mothers living in a slum area of Nairobi, Kenya. Contrary to stereotypes about families in sub-Saharan Africa, the active kin network of single mothers is relatively small and nearly a fifth of mothers do not receive any financial or child care assistance. Different types of kin offer different kinds of support according to culturally proscribed roles. However, support also depends heavily on kin's employment status, geographic proximity, and age. These findings offer a nuanced picture of how single women living in slum areas draw upon their kin network to cope with their daily demands as mothers.

How the Community Shapes Unmet Need for Modern Contraception: An Analysis of 44 Demographic and Health Surveys

Unmet need for modern contraception is a major public health concern in resource-constrained countries. Recent research supports the application of social-ecological theories to explain how characteristics of a woman's community shape modern contraception use. However, this research focuses largely on individual countries and uses a limited number of community-level effects. We fitted three random-effects logistic regression models to examine associations between 13 community-level variables and the odds of reporting unmet need, unmet need for spacing, and unmet need for limiting for all parous, female respondents in 44 DHS surveys collected in 2010-2015 (n=528,101). Community variables explain significant variance in unmet need between communities. Associations between community variables and unmet need differ by urban and rural residence. The results highlight several commonalities in how the community shapes unmet need across resource-constrained settings and may help in designing structural-level interventions.

Cancer is an adaptation that selects in animals against energy dissipation

As cancer usually follows reproduction, it is generally assumed that cancer does not select. Graham has however argued that juvenile cancer, which precedes reproduction, could during evolution have implemented a "cancer selection" that resulted in novel traits that suppress this juvenile cancer; an example is protection against UV sunlight-induced cancer, required for the emergence of terrestrial animals from the sea. We modify the cancer selection mechanism to the posited "cancer adaptation" mechanism, in which juvenile mortality is enhanced through the diminished care received by juveniles from their (grand) parents when these suffer from cancer in old age. Moreover, it is posited that the cancer adaptation selects against germline "dissipative genes", genes that result in enhanced free energy dissipation. Cancer's progression is interpreted as a cascade at increasing scale of repeated amplification of energy dissipation, a cascade involving heat shock, the Warburg effect, the cytokine IL-6, tumours, and hypermetabolism. Disturbance of any physiological process must enhance energy dissipation if the animal remains functioning normally, what explains multicausality, why "everything gives you cancer". The hypothesis thus comprises two newly invoked partial processes-diminished (grand) parental care and dissipation amplification-and results in a "selection against enhanced energy dissipation" which gives during evolution the benefit of energy conservation. Due to this benefit, cancer would essentially be an adaptation, and not a genetic disease, as assumed in the "somatic mutation theory". Cancer by somatic mutations is only a side process. The cancer adaptation hypothesis is substantiated by (1) cancer's extancy, (2) the failure of the somatic mutation theory, (3) cancer's initiation by a high temperature, (4) the interpretation of cancer's progression as a thermal process, and (5) the interpretation of tumours as organs that implement thermogenesis. The hypothesis could in principle be verified by monitoring in a population over several generations (1) the presence of dissipative genes, (2) the incidence of cancer, and (3) the beneficial effect of dissipative gene removal by cancer on starvation/famine survival.

Household structure vs. composition: Understanding gendered effects on educational progress in rural South Africa

BACKGROUND

Demographers have long been interested in the relationship between living arrangements and gendered outcomes for children in sub-Saharan Africa. Most extant research conflates household structure with composition and has revealed little about the pathways that link these components to gendered outcomes.

OBJECTIVES

First, we offer a conceptual approach that differentiates structure from composition with a focus on gendered processes that operate in the household; and second, we demonstrate the value of this approach through an analysis of educational progress for boys and girls in rural South Africa.

METHODS

We use data from the 2002 round of the Agincourt Health and Demographic Surveillance System. Our analytical sample includes 22,997 children aged 6-18 who were neither parents themselves nor lived with a partner or partner's family. We employ ordinary least squares regression models to examine the effects of structure and composition on educational progress of girls and boys.

RESULTS

The results suggest that non-nuclear structures are associated with similar negative effects for both boys and girls compared to children growing up in nuclear households. However, the presence of other kin in the absence of one or both parents results in gendered effects favouring boys.

CONCLUSION

The absence of any gendered effects when using a household structure typology suggests that secular changes to attitudes about gender equity trump any specific gendered processes stemming from particular configurations. On the other hand, gendered effects that appear when one or both parents are absent show that traditional gender norms and/or resource constraints continue to favour boys.

CONTRIBUTION

Despite the wealth of literature on household structure and children's educational outcomes in sub-Saharan Africa, the conceptual basis of these effects has not been well articulated. We have shown the value of unpacking household structure to better understand how gender norms and gendered resource allocations impact education.

Maternal union instability and childhood mortality risk in the Global South, 2010-14

Efforts to improve child survival in lower-income countries typically focus on fundamental factors such as economic resources and infrastructure provision, even though research from post-industrial countries confirms that family instability has important health consequences. We tested the association between maternal union instability and children's mortality risk in Africa, Latin America and the Caribbean, and Asia using children's actual experience of mortality (discrete-time probit hazard models) as well as their experience of untreated morbidity (probit regression). Children of divorced/separated mothers experience compromised survival chances, but children of mothers who have never been in a union generally do not. Among children of partnered women, those whose mothers have experienced prior union transitions have a higher mortality risk. Targeting children of mothers who have experienced union instability-regardless of current union status-may augment ongoing efforts to reduce childhood mortality, especially in Africa and Latin America where union transitions are common.

Marital Dissolution and Child Educational Outcomes in San Borja, Bolivia

Serial monogamy is likely an adaptive mating strategy for women when the expected future fitness gains with a different partner are greater than expected future fitness with one's current partner. Using interview data from more than 400 women in San Borja, Bolivia, discrete-time event history analyses and random effects regression analyses were conducted to examine predictors of marital dissolution, separated by remarriage status, and child educational outcomes. Male income was found to be inversely associated with women's risk of "divorce and remarriage," whereas female income is positively associated with women's risk of "divorce, but not remarriage." Children of women who divorce and remarry tend to have significantly lower educational outcomes than children of married parents, but women with higher incomes are able to buffer their children from the negative educational outcomes of divorce and remarriage. Counter to predictions, there is no evidence that women with kin in the community have a significant difference in likelihood of divorce or a buffering effect of child outcomes. In conclusion, predictors of divorce differ depending on whether the woman goes on to remarry, suggesting that male income may be a better predictor of a serial monogamy strategy whereas female income predicts marital dissolution only. Thus, women who are relatively autonomous because of greater income may not benefit from remarriage.

Under-five mortality according to maternal survival: a systematic review and meta-analysis

OBJECTIVE

To investigate, within so-called general populations, the relationship between maternal survival and mortality of children younger than five years.

METHODS

We conducted a systematic review of literature published between January 1990 and November 2016 that reported maternal vital status and the corresponding mortality of children younger than five years. Seven studies were included in a qualitative analysis and four in a random-effects meta-analysis. Summary estimates of the odds of dying by maternal survival were obtained and statistical heterogeneity estimated. Quality of the included studies and evidence was assessed using a Cochrane tool for assessing risk of bias and the Grading of Recommendations Assessment, Development and Evaluation criteria, respectively.

FINDINGS

Among children younger than five years, those whose mother had died were found to be 4.09 times (95% confidence interval, CI: 2.40-6.98) more likely to die than those with surviving mothers. Due to heterogeneity (I2: 83%), further pooled estimates were not possible. For children that were motherless as a result of maternal mortality, the increased odds of dying ranged from 1.40 (95% CI: 0.47-4.21) to 2.92 (95% CI: 1.21-7.04) among those aged between two and four years, 6.1 (95% CI: 2.27-16.77) to 33.78 (95% CI: 24.21-47.14) for those younger than one year and 4.39 (95% CI: 3.34-5.78) to 51.68 (95% CI: 20.26-131.80) for those younger than six months.

CONCLUSION

The loss of a mother was associated with increased mortality among children, especially when maternal death occurred in the first year of the child's life.

Effect of maternal death on child survival in rural West Africa: 25 years of prospective surveillance data in The Gambia

Background

The death of a mother is a tragedy in itself but it can also have devastating effects for the survival of her children. We aim to explore the impact of a mother’s death on child survival in rural Gambia, West Africa.

Methods

We used 25 years of prospective surveillance data from the Farafenni Health and Demographic surveillance system (FHDSS). Mortality rates per 1,000 child-years up to ten years of age were estimated and Kaplan-Meier survival curves plotted by maternal vital status. Cox proportional hazard models were used to examine factors associated with child survival.

Findings

Between 1^st April 1989 and 31^st December 2014, a total of 2, 221 (7.8%) deaths occurred during 152,906 child-years of follow up. Overall mortality rate was 14.53 per 1,000 child-years (95% CI: 13.93–15.14). Amongst those whose mother died, the rate was 25.89 (95% CI: 17.99–37.25) compared to 14.44 (95% CI: 13.84–15.06) per 1,000 child-years for those whose mother did not die. Children were 4.66 (95% CI: 3.15–6.89) times more likely to die if their mother died compared to those with a surviving mother. Infants whose mothers died during delivery or shortly after were up to 7 times more likely to die within the first month of life compared to those whose mothers survived. Maternal vital status was significantly associated with the risk of dying within the first 2 years of life (p-value <0.05), while this was no longer observed for children over 2 years of age (P = 0.872). Other factors associated with an increased risk of dying were living in more rural areas, and birth spacing and year of birth.

Conclusions

Mother’s survival is strongly associated with child survival. Our findings highlight the importance of the continuum of care for both the mother and child not only throughout pregnancy, and childbirth but beyond 6 weeks post-partum.

Exploring unobserved heterogeneity in perinatal and neonatal mortality risks: The case of an Italian sharecropping community, 1900-39

Previous researchers have found that traditional determinants explain only a limited part of the variation in perinatal and infant mortality at the family level. In the study reported in this paper, we explored the factors that make the perinatal/neonatal death risk more heterogeneous across families. We estimated logistic regressions with cluster random effects at the maternal level, using data from the Italian village of Granarolo from 1900 to 1939. We estimated the effects of selected predictors on perinatal/neonatal mortality and unexplained inter-family variation. We found that non-rural skilled and lower-skilled workers experienced higher perinatal and neonatal mortality risks. Unexplained heterogeneity at the maternal level was lower for women living in sharecropper families than for those in landless labourer and non-rural worker families. Unexplained perinatal and neonatal mortality components were also due to socio-economic differences and were not necessarily related only to maternal biological features or shared genetic frailty.

Reduced birth intervals following the birth of children with long-term illness: evidence supporting a conditional evolved response

Human birth interval length is indicative of the level of parental investment that a child will receive: a short interval following birth means that parental resources must be split with a younger sibling during a period when the older sibling remains highly dependent on their parents. From a life-history theoretical perspective, it is likely that there are evolved mechanisms that serve to maximize fitness depending on context. One context that would be expected to result in short birth intervals, and lowered parental investment, is after a child with low expected fitness is born. Here, data drawn from a longitudinal British birth cohort study were used to test whether birth intervals were shorter following the birth of a child with a long-term health problem. Data on the timing of 4543 births were analysed using discrete-time event history analysis. The results were consistent with the hypothesis: birth intervals were shorter following the birth of a child diagnosed by a medical professional with a severe but non-fatal medical condition. Covariates in the analysis were also significantly associated with birth interval length: births of twins or multiple births, and relationship break-up were associated with significantly longer birth intervals.

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

Previous research has found that the presence of grandparents, particularly grandmothers, is often positively associated with child survival. Little research has explored the potential mechanisms driving these associations. We use data from rural Guatemala to test whether contact with and direct investment (advice and financial) from grandparents is associated with child health, proxied by height. Our results demonstrate the complexity of family relationships and their influence on child health, suggesting that both cooperative and competitive relationships exist within the family. The clearest evidence we find for grandparental influence is that having a living paternal grandmother tends to be negatively associated with child height. By contrast, contact with maternal kin appears broadly to be beneficial for child height, although these relationships are weaker. These patterns are mirrored in maternal body mass index, suggesting grandparental influence acts partly through maternal health. These findings support the hypotheses that, under conditions of limited resources, family relationships may be competitive within the family lineage which shares the same resource base, but cooperative when there are few costs to cooperation. Finally, financial assistance from maternal grandfathers is positively correlated with infant length but negatively with the height of older children, perhaps because the receipt of financial support is an indication of need. The provision of advice shows no associations with child height.