Cohort profile: the Cebu longitudinal health and nutrition survey

DNA methylation-based estimators of telomere length show low correspondence with paternal age at conception and other measures of external validity of telomere length

In humans, DNA methylation (DNAm) based estimators of telomere length (TL) have been shown to better predict TL-associated variables (e.g., age, sex, and mortality) than TL itself. The biological significance of DNAm-based estimators of TL (DNAmTL) is unclear. In vitro DNAmTL shortens with cell replications, even when telomerase is maintaining TL. Telomerase is typically suppressed in humans, except in testes. Accordingly, sperm TL increases with age, and offspring with greater paternal age at conception (PAC) have longer TL. Thus, we expect that PAC associations with DNAmTL can shed light on whether in vivo cell replications in the presence of high telomerase activity (production of sperm) shorten DNAmTL or if PAC-lengthened TL causes lengthened DNAmTL. In a pre-registered analysis, using data from 1733 blood samples from the Philippines, we examined the association between paternal age at conception (PAC) and offspring DNAmTL. We did not find an association between PAC and DNAmTL but found a positive association of paternal grandfather's age at father's conception predicting grandchild's DNAmTL. In post hoc analyses, we examined how DNAmTL versus qPCR-measured TL (qPCR-TL) correlated with measures typically associated with TL. Contrary to previous findings, on almost all measures of external validity (correlations with parental TLs, southern blot TL, and age), qPCR-TL outperformed DNAmTL. The "kilobase" units of DNAm-based estimators of TL showed considerable deviations from southern blot-derived kilobase measures. Our findings suggest that DNAmTL is not a reliable index of inherited aspects of TL and underscores uncertainty about the biological meaning of DNAmTL.

Comparison of Infinium MethylationEPIC v2.0 to v1.0 for human population epigenetics: considerations for addressing EPIC version differences in DNA methylation-based tools

Background

The recently launched DNA methylation profiling platform, Illumina MethylationEPIC BeadChip Infinium microarray v2.0 (EPICv2), is highly correlated with measurements obtained from its predecessor MethylationEPIC BeadChip Infinium microarray v1.0 (EPICv1). However, the concordance between the two versions in the context of DNA methylation-based tools, including cell type deconvolution algorithms, epigenetic clocks, and inflammation and lifestyle biomarkers has not yet been investigated.

Findings

We profiled DNA methylation on both EPIC versions using matched venous blood samples from individuals spanning early to late adulthood across three cohorts. On combining the DNA methylomes of the cohorts, we observed that samples primarily clustered by the EPIC version they were measured on. Within each cohort, when we calculated cell type proportions, epigenetic age acceleration (EAA), rate of aging estimates, and biomarker scores for the matched samples on each version, we noted significant differences between EPICv1 and EPICv2 in the majority of these estimates. These differences were not significant, however, when estimates were adjusted for EPIC version or when EAAs were calculated separately for each EPIC version.

Conclusions

Our findings indicate that EPIC version differences predominantly explain DNA methylation variation and influence estimates of DNA methylation-based tools, and therefore we recommend caution when combining cohorts run on different versions. We demonstrate the importance of calculating DNA methylation-based estimates separately for each EPIC version or accounting for EPIC version either as a covariate in statistical models or by using version correction algorithms.

JA KIDS - Jamaica's second national birth cohort study: aims and methods

Birth cohort studies across the world have yielded information that has been used to inform policy and programme decisions that have improved the health and well-being of populations. A few such studies have been conducted in low- and middle-income countries due to funding, methodological and other challenges. This paper briefly reviews the methods of comprehensive birth cohort studies with extensive follow-up of participants through the life course conducted in low- and middle-income countries. It then reviews the first Jamaican birth cohort study of 1986 and discusses the methodological advances in implementing JA KIDS, the second Jamaican birth cohort study conducted in 2011. The aims and methods of JA KIDS are described in detail.

Ultraprocessed Food Intake during the Transition to Adulthood Varies According to Sociodemographic Characteristics and Maternal Intake in Cebu, Philippines

BACKGROUND

Ultraprocessed foods (UPFs) are associated with elevated risk of noncommunicable disease, but little is known about UPF intake and the individual-, household-, and community-level factors associated with it among adolescents in low- or middle-income countries.

OBJECTIVES

We estimated the association of UPF intake across adolescence with sociodemographic characteristics and maternal UPF intake in a Filipino cohort.

METHODS

Data were from 4 waves (1994-2005) of the Cebu Longitudinal Health and Nutrition Survey (n = 2068); participants were aged 11, 15, 18, and 21 y. Foods from 24-h recalls were classified using NOVA. We used two-part multilevel models to estimate time-varying associations of the odds and amount (percentage daily kilocalories) of UPF intake with sociodemographic characteristics and maternal UPF intake (none, below median among UPF-consuming mothers ["low"], at or above median ["high"]).

RESULTS

Median UPF intake (interquartile range [IQR]) among adolescents was 7.3% (IQR: 0, 17.2%) of daily kilocalories at age 11 y and 10.6% (IQR: 3.6, 19.6%) at 21 y. The odds and amount of adolescent UPF intake were positively associated with female sex, years of schooling, and household wealth and inversely associated with household size. The odds-but not amount-of adolescent UPF intake was positively associated with maternal education and urbanicity and inversely associated with the distance from a household's primary store/market. The association between odds of adolescent UPF intake and school enrollment was positive in adolescence but disappeared in early adulthood. Compared with offspring whose mothers did not consume UPFs, the odds of UPF intake among those whose mothers had low or high UPF intake was greater in adolescence, but there was no association once offspring became adults. At all ages, maternal UPF intake was positively associated with the amount of offspring intake.

CONCLUSIONS

Adolescent UPF intake varied across sociodemographic characteristics and was positively associated with maternal UPF intake, but not after adolescents entered adulthood.

Intimate partner violence, depression, and chronic low-grade inflammation among middle-aged women in Cebu, Philippines

OBJECTIVES

Recent discussions in human biology have highlighted how local ecological contexts shape the relationship between social stressors and health across populations. Chronic low-grade inflammation has been proposed as a pathway linking social stressors to health, with evidence concentrated in high-income Western contexts. However, it remains unclear whether this is an important pathway in populations where prevalence is lower due to lower adiposity and greater infectious exposures. To investigate this further, we tested associations between multiple types of intimate partner violence (IPV), a highly prevalent stressor and health crisis globally, and C-reactive protein (CRP), a commonly used measure of chronic low-grade inflammation, in Cebu, Philippines. For reference, we compared results for CRP to depression, a well-established and consistently observed health outcome of IPV.

METHODS

Data came from 1601 currently partnered women (ages 35-69 years) as part of the Cebu Longitudinal Health and Nutrition Survey. IPV exposures included physical, emotional, and controlling behavior. Depression scores were measured using a modified version of the Center for Epidemiologic Studies-Depression Scale for this population, whereas plasma CRP was measured from overnight-fasted morning blood samples.

RESULTS

All three types of IPV were associated with a higher depression score. However, none of the IPV measures were associated with CRP. In a post hoc interaction test, emotional IPV became positively associated with CRP as waist circumference increased above the mean.

CONCLUSIONS

Our results suggest a complex relationship between social stressors and chronic low-grade inflammation, which is likely dependent on the population-specific context of lifestyle and environmental factors.

Imputation accuracy across global human populations

Genotype imputation is now fundamental for genome-wide association studies but lacks fairness due to the underrepresentation of references from non-European ancestries. The state-of-the-art imputation reference panel released by the Trans-Omics for Precision Medicine (TOPMed) initiative improved the imputation of admixed African-ancestry and Hispanic/Latino samples, but imputation for populations primarily residing outside of North America may still fall short in performance due to persisting underrepresentation. To illustrate this point, we imputed the genotypes of over 43,000 individuals across 123 populations around the world and identified numerous populations where imputation accuracy paled in comparison to that of European-ancestry populations. For instance, the mean imputation r-squared (Rsq) for variants with minor allele frequencies between 1% and 5% in Saudi Arabians (n = 1,061), Vietnamese (n = 1,264), Thai (n = 2,435), and Papua New Guineans (n = 776) were 0.79, 0.78, 0.76, and 0.62, respectively, compared to 0.90-0.93 for comparable European populations matched in sample size and SNP array content. Outside of Africa and Latin America, Rsq appeared to decrease as genetic distances to European-ancestry reference increased, as predicted. Using sequencing data as ground truth, we also showed that Rsq may over-estimate imputation accuracy for non-European populations more than European populations, suggesting further disparity in accuracy between populations. Using 1,496 sequenced individuals from Taiwan Biobank as a second reference panel to TOPMed, we also assessed a strategy to improve imputation for non-European populations with meta-imputation, but this design did not improve accuracy across frequency spectra. Taken together, our analyses suggest that we must ultimately strive to increase diversity and size to promote equity within genetics research.

Pregnancy is linked to faster epigenetic aging in young women

A central prediction of evolutionary theory is that energy invested into reproduction comes at the expense of somatic maintenance and repair, accelerating biological aging. Supporting this prediction are findings that high fertility among women predicts shorter lifespan and poorer health later in life. However, biological aging is thought to begin before age-related health declines, limiting the applicability of morbidity and mortality for studying the aging process earlier in life. Here, we examine the relationship between reproductive history and biological aging in a sample of young (20 to 22yo) men and women from the Cebu Longitudinal Health and Nutrition Survey, located in the Philippines (n = 1,735). We quantify biological aging using six measures, collectively known as epigenetic clocks, reflecting various facets of cellular aging, health, and mortality risk. In a subset of women, we test whether longitudinal changes in gravidity between young and early-middle adulthood (25 to 31yo) are associated with changes in epigenetic aging during that time. Cross-sectionally, gravidity was associated with all six measures of accelerated epigenetic aging in women (n = 825). Furthermore, longitudinal increases in gravidity were linked to accelerated epigenetic aging in two epigenetic clocks (n = 331). In contrast, the number of pregnancies a man reported fathering was not associated with epigenetic aging among same-aged cohort men (n = 910). These effects were robust to socioecological, environmental, and immunological factors, consistent with the hypothesis that pregnancy accelerates biological aging and that these effects can be detected in young women in a high-fertility context.

Evidence that highly canalized fetal traits are sensitive to intergenerational effects of maternal developmental nutrition

OBJECTIVES

Maternal experiences before pregnancy predict birth outcomes, a key indicator of health trajectories, but the timing and pathways for these effects are poorly understood. Here we test the hypothesis that maternal pre-adult growth patterns predict pregnancy glucose and offspring fetal growth in Cebu, Philippines.

METHODS

Using multiple regression and path analysis, gestational age-adjusted birthweight and variables reflecting infancy, childhood, and post-childhood/adolescent weight gain (conditional weights) were used to predict pregnancy HbA1c and offspring birth outcomes among participants in the Cebu Longitudinal Health and Nutrition Survey.

RESULTS

Maternal early/mid-childhood weight gain predicted birth weight, length, and head circumference in female offspring. Late-childhood/adolescent weight gain predicted birth length, birth weight, skinfold thickness, and head circumference in female offspring, and head circumference in male offspring. Pregnancy HbA1c did not mediate relationships between maternal growth and birth size parameters.

DISCUSSION

In Cebu, maternal growth patterns throughout infancy, childhood, and adolescence predict fetal growth via a pathway independent of circulating glucose, with stronger impacts on female than male offspring, consistent with a role of developmental nutrition on offspring fetal growth. Notably, the strength of relationships followed a pattern opposite to what occurs in response to acute pregnancy stress, with strongest effects on head circumference and birth length and weakest on skinfolds. We speculate that developmental sensitivities are reversed for stable, long-term nutritional cues that reflect average local environments. These findings are relevant to public health and life-history theory as further evidence of developmental influences on health and resource allocation across the life course.

Properties of the full random-effect modeling approach with missing covariate data

During drug development, a key step is the identification of relevant covariates predicting between-subject variations in drug response. The full random effects model (FREM) is one of the full-covariate approaches used to identify relevant covariates in nonlinear mixed effects models. Here we explore the ability of FREM to handle missing (both missing completely at random (MCAR) and missing at random (MAR)) covariate data and compare it to the full fixed-effects model (FFEM) approach, applied either with complete case analysis or mean imputation. A global health dataset (20 421 children) was used to develop a FREM describing the changes of height for age Z-score (HAZ) over time. Simulated datasets (n = 1000) were generated with variable rates of missing (MCAR) covariate data (0%-90%) and different proportions of missing (MAR) data condition on either observed covariates or predicted HAZ. The three methods were used to re-estimate model and compared in terms of bias and precision which showed that FREM had only minor increases in bias and minor loss of precision at increasing percentages of missing (MCAR) covariate data and performed similarly in the MAR scenarios. Conversely, the FFEM approaches either collapsed at≥ $$ \ge $$ 70% of missing (MCAR) covariate data (FFEM complete case analysis) or had large bias increases and loss of precision (FFEM with mean imputation). Our results suggest that FREM is an appropriate approach to covariate modeling for datasets with missing (MCAR and MAR) covariate data, such as in global health studies.

Socioeconomic status is negatively associated with immunosenescence but positively associated with inflammation among middle-aged women in Cebu, Philippines

BACKGROUND

Socioeconomic status (SES) gradients in health are well-documented, and while biological pathways are incompletely understood, chronic inflammation and accelerated immune aging (immunosenescence) among lower SES individuals have been implicated. However, previous findings have come from samples in higher income countries, and it is unclear how generalizable they are to lower- and middle-income countries (LMIC) with different infectious exposures and where adiposity-an important contributor to chronic inflammation-might show different SES patterning. To address this gap, we explored associations between SES and inflammation and immunosenescence in a sample of women in Cebu, Philippines.

METHODS

Data came from the mothers of the Cebu Longitudinal Health and Nutrition Survey birth cohort (mean age: 47.7, range: 35-69 years). SES was measured as a combination of annual household income, education level, and assets. Chronic inflammation was measured using C-reactive protein (CRP) in plasma samples from 1,834 women. Immunosenescence was measured by the abundance of exhausted CD8T (CD8 + CD28-CD45RA-) and naïve CD8T and CD4T cells, estimated from DNA methylation in whole blood in a random subsample of 1,028. Possible mediators included waist circumference and a collection of proxy measures of pathogen exposure.

RESULTS

SES was negatively associated with the measures of immunosenescence, with slight evidence for mediation by a proxy measure for pathogen exposure from the household's drinking water source. In contrast, SES was positively associated with CRP, which was explained by the positive association with waist circumference.

CONCLUSIONS

Similar to higher income populations, in Cebu there is an SES-gradient in pathogen exposures and immunosenescence. However, lifestyle changes occurring more rapidly among higher SES individuals is contributing to a positive association between SES and adiposity and inflammation. Our results suggest more studies are needed to clarify the relationship between SES and inflammation and immunosenescence across LMIC.

Association between infectious exposures in infancy and epigenetic age acceleration in young adulthood in metropolitan Cebu, Philippines

OBJECTIVES

The drivers of human life expectancy gains over the past 200 years are not well-established, with a potential role for historical reductions in infectious disease. We investigate whether infectious exposures in infancy predict biological aging using DNA methylation-based markers that forecast patterns of morbidity and mortality later in life.

METHODS

N = 1450 participants from the Cebu Longitudinal Health and Nutrition Survey-a prospective birth cohort initiated in 1983-provided complete data for the analyses. Mean chronological age was 20.9 years when venous whole blood samples were drawn for DNA extraction and methylation analysis, with subsequent calculation of three epigenetic age markers: Horvath, GrimAge, and DunedinPACE. Unadjusted and adjusted least squares regression models were evaluated to test the hypothesis that infectious exposures in infancy are associated with epigenetic age.

RESULTS

Birth in the dry season, a proxy measure for increased infectious exposure in the first year of life, as well as the number of symptomatic infections in the first year of infancy, predicted lower epigenetic age. Infectious exposures were associated with the distribution of white blood cells in adulthood, which were also associated with measures of epigenetic age.

CONCLUSIONS

We document negative associations between measures of infectious exposure in infancy and DNA methylation-based measures of aging. Additional research, across a wider range of epidemiological settings, is needed to clarify the role of infectious disease in shaping immunophenotypes and trajectories of biological aging and human life expectancy.

Imputation Accuracy Across Global Human Populations

Genotype imputation is now fundamental for genome-wide association studies but lacks fairness due to the underrepresentation of populations with non-European ancestries. The state-of-the-art imputation reference panel released by the Trans-Omics for Precision Medicine (TOPMed) initiative contains a substantial number of admixed African-ancestry and Hispanic/Latino samples to impute these populations with nearly the same accuracy as European-ancestry cohorts. However, imputation for populations primarily residing outside of North America may still fall short in performance due to persisting underrepresentation. To illustrate this point, we curated genome-wide array data from 23 publications published between 2008 to 2021. In total, we imputed over 43k individuals across 123 populations around the world. We identified a number of populations where imputation accuracy paled in comparison to that of European-ancestry populations. For instance, the mean imputation r-squared (Rsq) for 1-5% alleles in Saudi Arabians (N=1061), Vietnamese (N=1264), Thai (N=2435), and Papua New Guineans (N=776) were 0.79, 0.78, 0.76, and 0.62, respectively. In contrast, the mean Rsq ranged from 0.90 to 0.93 for comparable European populations matched in sample size and SNP content. Outside of Africa and Latin America, Rsq appeared to decrease as genetic distances to European reference increased, as predicted. Further analysis using sequencing data as ground truth suggested that imputation software may over-estimate imputation accuracy for non-European populations than European populations, suggesting further disparity between populations. Using 1496 whole genome sequenced individuals from Taiwan Biobank as a reference, we also assessed a strategy to improve imputation for non-European populations with meta-imputation, which can combine results from TOPMed with smaller population-specific reference panels. We found that meta-imputation in this design did not improve Rsq genome-wide. Taken together, our analysis suggests that with the current size of alternative reference panels, meta-imputation alone cannot improve imputation efficacy for underrepresented cohorts and we must ultimately strive to increase diversity and size to promote equity within genetics research.

Inference for the dimension of a regression relationship using pseudo-covariates

In data analysis using dimension reduction methods, the main goal is to summarize how the response is related to the covariates through a few linear combinations. One key issue is to determine the number of independent, relevant covariate combinations, which is the dimension of the sufficient dimension reduction (SDR) subspace. In this work, we propose an easily-applied approach to conduct inference for the dimension of the SDR subspace, based on augmentation of the covariate set with simulated pseudo-covariates. Applying the partitioning principal to the possible dimensions, we use rigorous sequential testing to select the dimensionality, by comparing the strength of the signal arising from the actual covariates to that appearing to arise from the pseudo-covariates. We show that under a "uniform direction" condition, our approach can be used in conjunction with several popular SDR methods, including sliced inverse regression. In these settings, the test statistic asymptotically follows a beta distribution and therefore is easily calibrated. Moreover, the family-wise type I error rate of our sequential testing is rigorously controlled. Simulation studies and an analysis of newborn anthropometric data demonstrate the robustness of the proposed approach, and indicate that the power is comparable to or greater than the alternatives.

The rise and fall of SES gradients in heights around the world

We use data from a large sample of low- and middle-income countries to study the association (or "gradient") between child height and maternal education. We show that the gap in height between high- and low-SES children is small at birth, rises throughout childhood, and declines in adolescence as girls and boys go through puberty. This inverted U-shaped pattern is consistent with a degree of catch-up in linear height among children of low- relative to high-SES families, in partial contrast to the argument that height deficits cannot be overcome after the early years of life. This finding appears to be explained by the association between SES and the timing of puberty and therefore of the adolescent growth spurt: low-SES children start their adolescent growth spurt later and stop growing at later ages as well.

Contrasting speed and accuracy approaches to measure executive functions in three low-and middle-income countries

Executive functions (EF) can be measured by tests assessing accuracy, reaction times and by computing scores which combine these two components. Interpretation issues can arise from the use of different scoring methods across studies. Given that EF measures and their scoring methods are predominantly developed and validated in high income countries, little is known about the generalisability of such methods cross- culturally. The current paper compares two different established scoring approaches for measures of inhibition and cognitive flexibility: difference scores (which utilise reaction time only) and computed scores (combining accuracy and reaction time). We utilised data collected in adulthood from three low- and middle-income birth cohorts (Guatemala, Philippines, South Africa). Non-normal distributions were observed for both scoring methods in all three samples; however, this was more pronounced for the difference score method. Differing distribution patterns were observed across the three cohorts, which was especially evident in the Guatemala cohort, highlighting potential issues with using these methods across diverse populations. The data suggest that the computed scores may be a reliable measure of EF. However, the different ways of scoring and interpreting EF instruments need to be considered carefully for each population before use.

Quality of vital event data for infant mortality estimation in prospective, population-based studies: an analysis of secondary data from Asia, Africa, and Latin America

INTRODUCTION

Infant and neonatal mortality estimates are typically derived from retrospective birth histories collected through surveys in countries with unreliable civil registration and vital statistics systems. Yet such data are subject to biases, including under-reporting of deaths and age misreporting, which impact mortality estimates. Prospective population-based cohort studies are an underutilized data source for mortality estimation that may offer strengths that avoid biases.

METHODS

We conducted a secondary analysis of data from the Child Health Epidemiology Reference Group, including 11 population-based pregnancy or birth cohort studies, to evaluate the appropriateness of vital event data for mortality estimation. Analyses were descriptive, summarizing study designs, populations, protocols, and internal checks to assess their impact on data quality. We calculated infant and neonatal morality rates and compared patterns with Demographic and Health Survey (DHS) data.

RESULTS

Studies yielded 71,760 pregnant women and 85,095 live births. Specific field protocols, especially pregnancy enrollment, limited exclusion criteria, and frequent follow-up visits after delivery, led to higher birth outcome ascertainment and fewer missing deaths. Most studies had low follow-up loss in pregnancy and the first month with little evidence of date heaping. Among studies in Asia and Latin America, neonatal mortality rates (NMR) were similar to DHS, while several studies in Sub-Saharan Africa had lower NMRs than DHS. Infant mortality varied by study and region between sources.

CONCLUSIONS

Prospective, population-based cohort studies following rigorous protocols can yield high-quality vital event data to improve characterization of detailed mortality patterns of infants in low- and middle-income countries, especially in the early neonatal period where mortality risk is highest and changes rapidly.

Growth patterns in childhood and adolescence and adult body composition: a pooled analysis of birth cohort studies from five low and middle-income countries (COHORTS collaboration)

OBJECTIVE

We examined associations among serial measures of linear growth and relative weight with adult body composition.

DESIGN

Secondary data analysis of prospective birth cohort studies.

SETTINGS

Six birth cohorts from Brazil, Guatemala, India, the Philippines and South Africa.

PARTICIPANTS

4173 individuals followed from birth to ages 22-46 years with complete and valid weight and height at birth, infancy, childhood and adolescence, and body composition in adult life.

EXPOSURES

Birth weight and conditional size (standardised residuals of height representing linear growth and of relative weight representing weight increments independent of linear size) in infancy, childhood and adolescence.

PRIMARY OUTCOME MEASURES

Body mass index, fat mass index (FMI), fat-free mass index (FFMI), fat mass/fat-free mass ratio (FM/FFM), and waist circumference in young and mid-adulthood.

RESULTS

In pooled analyses, a higher birth weight and relative weight gains in infancy, childhood and adolescence were positively associated with all adult outcomes. Relative weight gains in childhood and adolescence were the strongest predictors of adult body composition (β (95% CI) among men: FMI (childhood: 0.41 (0.26 to 0.55); adolescence: 0.39 (0.27 to 0.50)), FFMI (childhood: 0.50 (0.34 to 0.66); adolescence: 0.43 (0.32 to 0.55)), FM/FFM (childhood: 0.31 (0.16 to 0.47); adolescence: 0.31 (0.19 to 0.43))). Among women, similar patterns were observed, but, effect sizes in adolescence were slightly stronger than in childhood. Conditional height in infancy was positively associated with FMI (men: 0.08 (0.03 to 0.14); women: 0.11 (0.07 to 0.16)). Conditional height in childhood was positively but weakly associated with women's adiposity. Site-specific and sex-stratified analyses showed consistency in the direction of estimates, although there were differences in their magnitude.

CONCLUSIONS

Prenatal and postnatal relative weight gains were positive predictors of larger body size and increased adiposity in adulthood. A faster linear growth in infancy was a significant but weak predictor of higher adult adiposity.

Longitudinal associations between parental migration and children's psychological well-being in Southeast Asia: The roles of caregivers' mental health and caregiving quality

OBJECTIVE

This study investigates the longer-term effects of parental migration on the psychological well-being of children who stay behind in two major labor-sending countries in Southeast Asia, namely, Indonesia and the Philippines. Adopting the framework of the 'care triangle', we further examine how caregivers' mental health and caregiving quality moderate the associations between parental migration and children's psychological well-being.

METHODS

Using longitudinal data collected in 2008 and 2016/17, we assess children's psychological well-being during early childhood (aged 3-5 years) and again in adolescence (aged 11-13 years). We apply both fixed-effects and random-effects models, using the Hausman test to indicate the preferred model.

RESULTS

The findings indicate that there is no significant longer-term effect of parental migration on children's psychological well-being, but parental migration tends to show adverse effects on Filipino children's psychological well-being when they are cared for by a caregiver with poor mental health.

CONCLUSIONS

The two-country comparison demonstrates the complexities of understanding the gender-based influences of parental migration on children's psychological well-being. The findings also highlight the caregiver's role in maintaining frequent communications with migrant parents within the care triangle, which is crucial to children's well-being.

Prenatal household size and composition are associated with infant fecal bacterial diversity in Cebu, Philippines

OBJECTIVES

The gut microbiome (GM) connects physical and social environments to infant health. Since the infant GM affects immune system development, there is interest in understanding how infants acquire microbes from mothers and other household members.

MATERIALS AND METHODS

As a part of the Cebu Longitudinal Health and Nutrition Survey (CLHNS), we paired fecal samples (proxy for the GM) collected from infants living in Metro Cebu, Philippines at 2 weeks (N = 39) and 6 months (N = 36) with maternal interviews about prenatal household composition. We hypothesized that relationships between prenatal household size and composition and infant GM bacterial diversity (as measured in fecal samples) would vary by infant age, as well as by household member age and sex. We also hypothesized that infant GM bacterial abundances would differ by prenatal household size and composition.

RESULTS

Data from 16 S rRNA bacterial gene sequencing show that prenatal household size was the most precise estimator of infant GM bacterial diversity, and that the direction of the association between this variable and infant GM bacterial diversity changed between the two time points. The abundances of bacterial families in the infant GM varied by prenatal household variables.

CONCLUSIONS

Results highlight the contributions of various household sources to the bacterial diversity of the infant GM, and suggest that prenatal household size is a useful measure for estimating infant GM bacterial diversity in this cohort. Future research should measure the effect of specific sources of household bacterial exposures, including social interactions with caregivers, on the infant GM.

Early-life stature, preschool cognitive development, schooling attainment, and cognitive functioning in adulthood: a prospective study in four birth cohorts

BACKGROUND

Nutrition is important for growth and brain development and therefore cognitive ability. Growth faltering in early childhood, an important indicator of early adversity, is associated with poorer developmental outcomes, some into adulthood, but this association probably reflects early-life deprivation. We aimed to investigate the associations between early-life stature, child IQ, and adult IQ.

METHODS

In this cohort study, we used prospective longitudinal data collected in four birth cohorts from Brazil (born in 1993), Guatemala (born in 1969-77), the Philippines (born in 1983-84), and South Africa (born in 1990). Using multivariable linear models, we estimated the relative contributions of early-life stature, child IQ, and schooling (highest school year completed) to adult IQ, including interaction effects among the early-childhood measures and schooling.

FINDINGS

We included 2614 individuals in the analysis. Early-life stature was associated with adult IQ (range across eight site-by-sex groups -0·14 to 3·17 IQ points) and schooling (-0·05 to 0·77 years) per height-for-age Z-score. These associations were attenuated when controlling for child IQ (-0·86 to 1·72 for adult IQ and -0·5 to 0·60 for schooling). The association of early-life stature with adult IQ was further attenuated when controlling for schooling (-1·86 to 1·21). Child IQ was associated with adult IQ (range 3·91 to 10·02 points) and schooling (0·25 to 1·30 years) per SD of child IQ in all groups; these associations were unattenuated by the addition of early-life stature to the models. The interaction between schooling and child IQ, but not that between schooling and early-life stature, was positively associated with adult IQ across groups.

INTERPRETATION

The observed associations of early-life stature with adult IQ and schooling varied across cohorts and sexes and explained little variance in adult IQ beyond that explained by child IQ. These findings suggest that interventions targeted at growth for health and early development are important. Our results are consistent with the inference that improving long-term cognitive outcomes might require interventions that more specifically target early cognitive ability.

FUNDING

Bill & Melinda Gates Foundation.

Birth weight and maternal energy status during pregnancy as predictors of epigenetic age acceleration in young adults from metropolitan Cebu, Philippines

Epigenetic clocks quantify regular changes in DNA methylation that occur with age, or in relation to biomarkers of ageing, and are strong predictors of morbidity and mortality. Here, we assess whether measures of fetal nutrition and growth that predict adult chronic disease also predict accelerated biological ageing in young adulthood using a suite of commonly used epigenetic clocks. Data come from the Cebu Longitudinal Health and Nutrition Survey (CLHNS), a long-running cohort followed since birth in metropolitan Cebu, Philippines. Past work has shown that birth weight (BW) and the mother's arm fat during pregnancy (a measure of pregnancy energy status) relate inversely to health outcomes in the CLHNS but primarily in males. Genome-wide DNA methylation was assessed in whole blood using the Infinium EPIC array. Participants included males (n=895) and females (n=803) measured in 2005 (20.8-22.5 years). Clocks included the Hannum and Horvath clocks trained on chronological age, the DNAmPhenoAge and DNAmGrimAge clocks trained on clinical biomarkers, the Dunedin pace of ageing (DunedinPACE) clock trained on longitudinal changes in ageing biomarkers, and the DNAmTL clock trained on leukocyte telomere length. In males, lower BW predicted advanced biological ageing using the Hannum, DNAmPhenoAge, DunedinPoAm, and DNAmTL clocks. In contrast, BW did not predict any clock in female participants. Participants' mothers' pregnancy arm fat only predicted DNAmTL in males. These findings suggest that epigenetic clocks are a useful tool for gauging long-term outcomes predicted by fetal growth, and add to existing evidence in the CLHNS for sex differences in these relationships.

Conditional wealth to estimate association of wealth mobility with health and human capital in low- and middle-income country cohorts

Temporally harmonized asset indices allow the study of changes in relative wealth (mean, variance, social mobility) over time and its association with adult health and human capital in cohort studies. Conditional measures are the unexplained residuals of an indicator regressed on its past values. Using such measures, previously used to study the relative importance of key life stages for anthropometric growth, we can identify specific life stages during which changes in relative wealth are important for adult health in longitudinal studies. We discuss the assumptions, strengths and limitations of this methodology as applied to relative wealth. We provide an illustrative example using a publicly-available longitudinal dataset and show how relative wealth changes at different life stages are differentially associated with body mass index in adulthood.

Lee N, Kelly P, Trilok-Kumar G, Chisenga M, Kweka B, Faurholt-Jepsen D, Krogh-Madsen R, AM Shaw J, M. Paglinawan-Modoc D, Solon J, Frahm Olsen M, Stefanovski D, Cox S, Nitsch D, Keogh R, Filteau S. Long-term health after Severe Acute Malnutrition in children and adults- the role of the Pancreas (SAMPA): Protocol

Background: Prenatal growth retardation may increase the risk of later chronic non-communicable diseases (NCDs), including diabetes; however, long-term effects of wasting malnutrition in childhood or adulthood are less studied. Pancreatic exocrine and endocrine functions, both critical for nutrition and NCD aetiology, may not fully recover following malnutrition. However, the evidence and mechanistic information is piecemeal. We hypothesise that wasting malnutrition at any age has long-term detrimental effects on endocrine and exocrine pancreatic structure and function. Methods: The SAMPA international research programme will assess pancreatic structure and function in 3700 participants from ongoing observational nutrition cohorts, two adolescent and four adult, in Zambia, Tanzania, Philippines, and India. Pancreas size, structure, and calcification will be assessed by ultrasound and computed tomography (CT) scan; exocrine function by faecal elastase and serum lipase; and endocrine function by haemoglobin A1c (HbA1c) and blood glucose, insulin and C-peptide concentrations during an oral glucose tolerance test (OGTT). In-depth hormonal analyses of incretins, glucagon, proinsulin and trypsinogen during OGTT and intravenous glucose tolerance tests will be done in subsets of adult participants. Pancreatic size and function outcomes will be compared between people with and without prior wasting malnutrition. Analyses will investigate effect modification by sex, current age, time since malnutrition, current body mass index and dietary patterns. Mathematical modelling of OGTT data will be used to estimate the relative contribution to glucose dysregulation of decreased insulin production, changes in insulin clearance and increased insulin resistance. Proinsulin/insulin ratio will be analysed in archived samples from the Tanzanian cohort using a nested case-control design to investigate whether abnormal values precede diabetes. Conclusions: SAMPA, a large-scale multi-centre research programme using data from people with or without prior wasting malnutrition to assess several aspects of pancreatic phenotype, will provide coherent evidence for future policies and programmes for malnutrition and diabetes.

Global Trends in the Availability of Dietary Data in Low and Middle-Income Countries

Individual-level quantitative dietary data can provide suitably disaggregated information to identify the needs of all population sub-groups, which can in turn inform agricultural, nutrition, food safety, and environmental policies and programs. The purpose of this discussion paper is to provide an overview of dietary surveys conducted in low- and middle-income countries (LMICs) from 1980 to 2019, analyzing their key characteristics to understand the trends in dietary data collection across time. The present study analyzes the information gathered by the Food and Agriculture Organization of the United Nations/World Health Organization Global Individual Food consumption data Tool (FAO/WHO GIFT). FAO/WHO GIFT is a growing repository of individual-level dietary data and contains information about dietary surveys from around the world, collected through published survey results, literature reviews, and direct contact with data owners. The analysis indicates an important increase in the number of dietary surveys conducted in LMICs in the past four decades and a notable increase in the number of national dietary surveys. It is hoped that this trend continues, together with associated efforts to validate and standardize the dietary methods used. The regular implementation of dietary surveys in LMICs is key to support evidence-based policies for improved nutrition.

Maternal epigenetic clocks measured during pregnancy do not predict gestational age at delivery or offspring birth outcomes: a replication study in metropolitan Cebu, Philippines

Adverse birth outcomes, such as early gestational age and low birth weight, can have lasting effects on morbidity and mortality, with impacts that persist into adulthood. Identifying the maternal factors that contribute to adverse birth outcomes in the next generation is thus a priority. Epigenetic clocks, which have emerged as powerful tools for quantifying biological aging and various dimensions of physiological dysregulation, hold promise for clarifying relationships between maternal biology and infant health, including the maternal factors or states that predict birth outcomes. Nevertheless, studies exploring the relationship between maternal epigenetic age and birth outcomes remain few. Here, we attempt to replicate a series of analyses previously reported in a US-based sample, using a larger similarly aged sample (n = 296) of participants of a long-running study in the Philippines. New pregnancies were identified prospectively, dried blood spot samples were collected during the third trimester, and information was obtained on gestational age at delivery and offspring weight after birth. Genome-wide DNA methylation was assessed with the Infinium EPIC array. Using a suite of 15 epigenetic clocks, we only found one significant relationship: advanced age on the epigenetic clock trained on leptin predicted a significantly earlier gestational age at delivery (β = - 0.15, p = 0.009). Of the other 29 relationships tested predicting gestational age and offspring birth weight, none were statistically significant. In this sample of Filipino women, epigenetic clocks capturing multiple dimensions of biology and health do not predict birth outcomes in offspring.

Neither environmental unpredictability nor harshness predict reliance on alloparental care among families in Cebu, Philippines

Alloparental caregiving is key to humans' highly flexible reproductive strategies. Across species and across societies, alloparental care is more common in harsh and/or unpredictable environments (HUEs). Currently, however, it is unclear whether HUEs predict intra-population variation in alloparental care, or whether early life HUEs might predict later alloparental care use in adulthood, consistent with adaptive developmental plasticity. We test whether harshness measures (socioeconomic status (SES), environmental hygiene, crowding) and unpredictability measures (parental unemployment, paternal absence, household moves) predicted how much alloparental assistance families in Cebu, Philippines received, in a multigenerational study with data collected across four decades. Though worse environmental hygiene predicted more concurrent alloparental care in 1994, we found little evidence that HUEs predict within-population variation in alloparental care in this large-scale, industrialized society. Indeed, less-crowded conditions and higher SES predicted more alloparental care, not less, in the 1980s and in 2014 respectively, while paternal absence in middle childhood predicted less reliance on alloparental care in adulthood. In this cultural context, our results generally do not provide support for the translation of interspecific or intersocietal patterns linking HUEs and alloparental care to intra-population variation in alloparental care, nor for the idea that a reproductive strategy emphasizing alloparental care use may be preceded by early life HUEs.

Immune cell type and DNA methylation vary with reproductive status in women: possible pathways for costs of reproduction

Background

Consistent with evolutionarily theorized costs of reproduction (CoR), reproductive history in women is associated with life expectancy and susceptibility to certain cancers, autoimmune disorders and metabolic disease. Immunological changes originating during reproduction may help explain some of these relationships.

Methodology

To explore the potential role of the immune system in female CoR, we characterized leukocyte composition and regulatory processes using DNA methylation (DNAm) in a cross-sectional cohort of young (20–22 years old) women differing in reproductive status.

Results

Compared to nulliparity, pregnancy was characterized by differential methylation at 828 sites, 96% of which were hypomethylated and enriched for genes associated with T-cell activation, innate immunity, pre-eclampsia and neoplasia. Breastfeeding was associated with differential methylation at 1107 sites (71% hypermethylated), enriched for genes involved in metabolism, immune self-recognition and neurogenesis. There were no significant differences in DNAm between nulliparous and parous women. However, compared to nullipara, pregnant women had lower proportions of B, CD4T, CD8T and natural killer (NK) cells, and higher proportions of granulocytes and monocytes. Monocyte counts were lower and NK counts higher among breastfeeding women, and remained so among parous women.

Implications

Our findings point to widespread differences in DNAm during pregnancy and lactation. These effects appear largely transient, but may accumulate with gravidity become detectable as women age. Nulliparous and parous women differed in leukocyte composition, consistent with more persistent effects of reproduction on cell type. These findings support transient (leukocyte DNAm) and persistent (cell composition) changes associated with reproduction in women, illuminating potential pathways contributing to CoR.

Lay Summary: Evolutionary theory and epidemiology support costs of reproduction (CoR) to women’s health that may involve changes in immune function. We report differences in immune cell composition and gene regulation during pregnancy and breastfeeding. While many of these differences appear transient, immune cell composition may remain, suggesting mechanisms for female CoR.

Systematic Review and Meta-analysis: Depressive Symptoms and Risky Behaviors Among Adolescents in Low- and Middle-Income Countries

OBJECTIVE

Several studies conducted in high-income countries have found an association between depressive symptoms and risky behaviors among adolescents. Evidence from low- and middle-income countries (LMICs), where 90% of the world's adolescents live, remains scarce. This meta-analysis systematically reviewed evidence examining the association between depressive symptoms and risky behaviors among adolescents in LMICs.

METHOD

Fifteen electronic databases were searched for published or unpublished cohort and case-control studies about adolescents in LMICs. The primary outcome was the association (odds ratio [OR]) between depressive symptoms and risky sexual behavior and substance use. Secondary outcomes included delinquency, adverse school behavior, self-harm, and suicidal behavior. ORs from all studies were pooled using the random-effects model. Quality of studies was assessed using the Newcastle-Ottawa scale, and strength of the overall body of evidence was assessed using Grading of Recommendations, Assessment, Development and Evaluation.

RESULTS

Searches yielded 31,148 potentially relevant studies. After screening, 33 studies were included in the systematic review, of which 30 comprised the meta-analysis. Studies encompassed 35,918 adolescents living in 17 LMICs: 5 from Africa, 7 from Asia, and 5 from Latin America and the Caribbean. Adolescents with depressive symptoms were more likely to engage in risky sexual behavior (OR 1.3 95% CI 1.1-1.5) and substance use (OR 1.8, 95% CI 1.4-2.2) compared with nondepressed adolescents. Results for secondary outcomes showed a similar pattern, with higher delinquency (OR 3.2, 95% CI 1.8-5.6), self-harm (OR 4.4, 95% CI 1.3-14.4), and suicidal behavior (OR 6.6, 95% CI 2.3-18.9) among adolescents with depression compared with healthy adolescents.

CONCLUSION

This study suggests that adolescents with depression in LMICs carry a double burden: depression and increased risk of engaging in risky behaviors. This combination may lead to further psychological and physical health problems that persist over the life course and may impose a health burden on society as a whole. Taken together, these findings highlight the urgent need for scalable and sustainable approaches to prevent and/or treat depression among adolescents in resource-poor settings.

Subjective social status is associated with happiness but not weight status or psychological distress: An analysis of three prospective birth cohorts from low- and middle-income countries

BACKGROUND

Subjective social status (SSS, perception of social position relative to a frame of reference) has been associated with physical, mental and socio-emotional wellbeing. However, these associations may be susceptible to unmeasured confounding by life course objective socio-economic position (SEP; such as wealth, education and employment) and life satisfaction.

PURPOSE

To estimate the association of position on ladders of perceived community respect and perceived economic status with weight, distress and wellbeing, independent of objective SEP in cohorts from three low and middle-income countries.

METHODS

We used data from birth cohorts in Guatemala (n = 1258), Philippines (n = 1323) and South Africa (n = 1393). We estimated the association of perceived community respect and perceived economic status with body mass index (kg/m²), the World Health Organization's Self-Reported Questionnaire-20 (SRQ-20) for psychological distress, and Lyubomirsky's Subjective Happiness Scale. We estimated these associations using robust linear regression models adjusting for indicators of life course objective SEP, early life characteristics, adult covariates, and life satisfaction.

RESULTS

Participants in South Africa (age 27-28y) rated themselves higher on average for both the respect (7 vs 5 in Guatemala and 6 in Philippines) and economic (5 vs 3 in Guatemala and 4 in Philippines) ladder measures. Position on neither community respect nor economic ladders were associated with BMI or psychological distress. Higher position on community respect (Guatemala: 0.03, 95%CI: 0.01, 0.04; Philippines: 0.03, 95% CI: 0.02, 0.05; South Africa: 0.07, 95%CI: 0.04, 0.09) and economic (Guatemala: 0.02, 95%CI: 0, 0.04; Philippines: 0.04, 95%CI: 0.02, 0.07; South Africa: 0.07, 95%CI: 0.04, 0.10) ladders were associated with greater happiness.

CONCLUSIONS

Subjective social status showed small but consistent associations with happiness in birth cohorts independent of life-course SEP.

Changes in asset-based wealth across the life course in birth cohorts from five low- and middle-income countries

Background

Temporally-harmonized asset-based measures of wealth can be used to study the association of life-course wealth exposures in the same scale with health outcomes in low- and middle-income countries (LMICs). The within-individual longitudinal stability of asset-based indices of wealth in LMICs is poorly understood.

Methods

Using data from five birth cohorts from three continents, we developed temporally-harmonized asset indices over the life course through polychoric principal component analysis of a common set of assets collected consistently over time (18 years in Brazil to 50 years in Guatemala). For each cohort, we compared the harmonized index to cross-sectional indices created using more comprehensive asset measures using rank correlations. We evaluated the rank correlation of the harmonized index in early life and adulthood with maternal schooling and own attained schooling, respectively.

Results

Temporally-harmonized asset indices developed from a consistently-collected set of assets (range: 10 in South Africa to 30 in Philippines) suggested that mean wealth improved over time for all birth cohorts. Cross-sectional indices created separately for each study wave were correlated with the harmonized index for all cohorts (Brazil: r = 0.78 to 0.96; Guatemala: r = 0.81 to 0.95; India: 0.75 to 0.93; Philippines: r = 0.92 to 0.99; South Africa: r = 0.84 to 0.96). Maternal schooling (r = 0.15 to 0.56) and attained schooling (r = 0.23 to 0.53) were positively correlated with the harmonized asset index in childhood and adulthood respectively.

Conclusions

Temporally-harmonized asset indices displayed coherence with cross-sectional indices as well as construct validity with schooling.

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Temporally-harmonized asset indices are useful to assess relative importance of wealth at different life stages with health on the same scale.

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Harmonized indices using a subset of assets were correlated with cross-sectional asset indices using all available assets in five LMIC birth cohorts.

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Harmonized indices displayed construct validity, as demonstrated by its correlation with schooling.

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Harmonized indices were robust to alternate specifications such as shorter lists of assets, study years, and factor extraction procedures.

Stunting, IQ, and final school attainment in the Cebu Longitudinal Health and Nutrition Survey birth cohort

School attainment is an important aspect of human capital, and a key determinant of long-term health and well-being. Early life deprivation and poor nutritional status are well known predictors of school entry and progression. We examine the persistence of early life influences and subsequent socioeconomic disadvantage (SED) across the multiple school continuation decisions that lead to final school attainment. Using data from a Philippine birth cohort followed for 35 years, we model 6 continuation decisions: Did not complete elementary school, elementary graduate only (completed grade 6), some secondary schooling, high school graduate, some postsecondary schooling, and college graduate, as well as total years of schooling. We estimate the association of school attainment with early life length for age Z-score (LAZ at 2 years of age) and cognitive development (IQ) as well as underlying indicators of SED and other family influences through early adulthood. The analysis sample includes >1900 participants in the Cebu Longitudinal Health and Nutrition Survey. Females completed, on average, one year more schooling than males, and twice as many females as males were college graduates (29.1 vs 15.0 %). LAZ and one standard deviation of IQ were each independently associated with 0.4 more years of attained schooling. A path model demonstrated strong direct associations of SED with years of schooling as well as indirect associations through LAZ and IQ. Sequential logits used to estimate continuing education decisions show persistent associations of early life LAZ and IQ and schooling even after accounting for changing SED of households over the schooling life course. Filipino parents had high but often unmet educational aspirations for their children because of the child's loss of interest in school and perceived financial barriers. Results further emphasize the importance of early life SED as a key risk factor for suboptimal school attainment.

The influence of natural disasters on violence, mental health, food insecurity, and stunting in the Philippines: Findings from a nationally representative cohort

Background

Climate change is leading to an increased number of natural disasters. Children from low- and middle-income countries are disproportionately affected. The impacts of exposure to multiple natural disasters on the development of children are not well understood. The Philippines had 6.5 million people affected by natural disasters in 2018 and is therefore an ideal country in which to study the cumulative effects of natural disasters on human development.

Methods

We used wave 1 (2016–17) of the Longitudinal Cohort Study on the Filipino Child, a nationally representative cohort study of 4952 10-year-old children, to examine the impact of natural disasters. For caregivers, we examined mental health, family violence, and food insecurity. For children, we examined exposure to violence and stunting. We used random effects models to estimate the associations between natural disasters and children's development outcomes and caregivers' outcomes, after adjusting for neighbourhood, demographic, and geographic variables. Disaster exposure was measured using caregiver-reported measures of cumulative exposure and cumulative impact of disasters, average neighbourhood reports and data linked from the International Disaster Database (EM-DAT), an independent measure of community exposure to disaster.

Findings

We found that experiencing natural disasters, as measured by neighbourhood reports, was associated with higher levels of family violence in the previous 12 months, parenting stress, children witnessing physical violence, physical abuse of children, stunting in children, and greater food insecurity. Associations with individual self-reported exposure showed was similar. Associations with natural disasters measured using EM-DAT data showed a similar pattern: exposure to greater numbers of natural disasters was associated with higher levels of family violence, physical abuse of children, stunting in children, and food insecurity. Impacts of disasters was associated with higher levels of family violence, depression and food insecurity.

Interpretation

This is the first national study to document that cumulative measures of natural disasters had small, but wide-ranging, impacts on children and their caregivers. Further research is needed to identify factors that will protect populations who are at risk of high levels of natural disasters to ensure the optimal development of children.

Funding

The Philippines Project, The Australian National University.

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The implications of multiple natural disasters for child development are not well understood.

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First national study on the impact of multiple natural disasters on children.

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More natural disasters associated with child physical abuse and family violence.

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Exposure to a greater number of natural disasters associated with stunting and food insecurity.

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More natural disasters led to worse caregivers' depression and stress.

Patterns of Growth in Childhood in Relation to Adult Schooling Attainment and Intelligence Quotient in 6 Birth Cohorts in Low- and Middle-Income Countries: Evidence from the Consortium of Health-Oriented Research in Transitioning Societies (COHORTS)

BACKGROUND

Growth faltering has been associated with poor intellectual performance. The relative strengths of associations between growth in early and in later childhood remain underexplored.

OBJECTIVES

We examined the association between growth in childhood and adult human capital in 5 low- and middle-income countries (LMICs).

METHODS

We analyzed data from 9503 participants in 6 prospective birth cohorts from 5 LMICs (Brazil, Guatemala, India, the Philippines, and South Africa). We used linear and quasi-Poisson regression models to assess the associations between measures of height and relative weight at 4 age intervals [birth, age ∼2 y, midchildhood (MC), adulthood] and 2 dimensions of adult human capital [schooling attainment and Intelligence Quotient (IQ)].

RESULTS

Meta-analysis of site- and sex-specific estimates showed statistically significant associations between size at birth and height at ∼2 y and the 2 outcomes (P < 0.001). Weight and length at birth and linear growth from birth to ∼2 y of age (1 z-score difference) were positively associated with schooling attainment (β: 0.13; 95% CI: 0.08, 0.19, β: 0.17; 95% CI: 0.07, 0.32, and β: 0.25, 95% CI: 0.10, 0.40, respectively) and adult IQ (β: 0.74, 95% CI: 0.35, 1.14, β: 0.73, 95% CI: 0.35, 1.10, and β: 1.52, 95% CI: 0.96, 2.08, respectively). Linear growth from age 2 y to MC and from MC to adulthood was not associated with higher school attainment or IQ. Change in relative weight in early childhood, MC, and adulthood was not associated with either outcome.

CONCLUSIONS

Linear growth in the first 1000 d is a predictor of schooling attainment and IQ in adulthood in LMICs. Linear growth in later periods was not associated with either of these outcomes. Changes in relative weight across the life course were not associated with schooling and IQ in adulthood.

The effect of gender targeting of food transfers on child nutritional status: Experimental evidence from the Bolivian Amazon

Some research suggests women are more likely to allocate additional resources to their children than are men. This perception has influenced policies such as in-kind food transfer programs and cash transfer programs, which often target women recipients. We assess whether targeting in-kind rice transfers to female versus male adult household members has a differential impact on children's short-run nutritional status. We estimate the impacts of transfers of edible rice and rice seeds, randomly allocated to female or male adults, on three anthropometric indicators: BMI-for-age, arm-muscle area, and triceps skinfold thickness. The trial includes 481 children aged 3-11 years in a horticultural-foraging society of native Amazonians in Bolivia. On average, the gender of the transfer recipient does not influence child anthropometric dimensions, possibly due to norms of cooperation and sharing within and between households. We find limited evidence of heterogeneity in impacts. Transfers to women help children who were growth stunted at baseline to partially catch-up to their better-nourished age-sex peers and help boys (but not girls) and children in higher-income households increase their BMI-for-age. The results of this research point to the importance of considering cultural context in determining if allocating food transfers according to gender are most effective.

An application of Systematic Anomalous Case Analysis to improve models predicting contraceptive use in the Philippines

Amidst persistently high unintended pregnancy rates and lags in contraceptive use, novel methodological approaches may prove useful in investigating sexual and reproductive health outcomes in the Philippines. Systematic Anomalous Case Analysis (SACA) - a mixed-methods technique - was employed to examine predictors of women's lifetime contraceptive use. First, multivariable, longitudinal Poisson regression models predicted fertility and sexual debut using the 1998-2009 Cebu Longitudinal Health and Nutrition Surveys (CLHNS), then regression outliers and normative cases were used to identify 48 participants for in-depth interviews (2013-2014) for further examination. Qualitative findings from 24 women highlighted 'control over life circumstances' was critical, prompting the addition of two items to the original quantitative models predicting any contraceptive use (n=532). Each of the items, 'what happens to [them] is their own doing' and '[I] do not [have] enough control over direction life is taking [me]', significantly and independently predicted any contraceptive use (aOR: 2.37 (CI: 1.24-4.55) and aOR: 0.46 (CI: 0.28-0.77), respectively). The findings demonstrate the utility of SACA to improve the understanding and measurement of sexual and reproductive health outcomes and underscore the importance of integrating psychosocial constructs into existing models of fertility and reproductive behaviour in the Philippines to improve sexual and reproductive health outcomes.

Socioeconomic status effects on health vary between rural and urban Turkana

Background and objectives

Understanding the social determinants of health is a major goal in evolutionary biology and human health research. Low socioeconomic status (often operationalized as absolute material wealth) is consistently associated with chronic stress, poor health and premature death in high-income countries. However, the degree to which wealth gradients in health are universal—or are instead made even steeper under contemporary, post-industrial conditions—remains poorly understood.

Methodology

We quantified absolute material wealth and several health outcomes among a population of traditional pastoralists, the Turkana of northwest Kenya, who are currently transitioning toward a more urban, market-integrated lifestyle. We assessed whether wealth associations with health differed in subsistence-level versus urban contexts. We also explored the causes and consequences of wealth-health associations by measuring serum cortisol, potential sociobehavioral mediators in early life and adulthood, and adult reproductive success (number of surviving offspring).

Results

Higher socioeconomic status and greater material wealth predicts better self-reported health and more offspring in traditional pastoralist Turkana, but worse cardiometabolic health and fewer offspring in urban Turkana. We do not find robust evidence for either direct biological mediators (cortisol) or indirect sociobehavioral mediators (e.g. adult diet or health behaviors, early life experiences) of wealth–health relationships in either context.

Conclusions and implications

While social gradients in health are well-established in humans and animals across a variety of socioecological contexts, we show that the relationship between wealth and health can vary within a single population. Our findings emphasize that changes in economic and societal circumstances may directly alter how, why and under what conditions socioeconomic status predicts health.

Lay Summary

High socioeconomic status predicts better health and more offspring in traditional Turkana pastoralists, but worse health and fewer offspring in individuals of the same group living in urban areas. Together, our study shows that under different economic and societal circumstances, wealth effects on health may manifest in very different ways.

Inter-relationships between percentage body fat, relative subischial leg length and body mass index among adolescents and adults from the Limbu community of Darjeeling, West Bengal

Leg length in humans is considered to be an indicator of the long-term impact of quality of childhood living conditions and nutritional status. The main objective of this study was to evaluate the magnitude of association of percentage body fat (PBF) with relative subischial leg length (RSLL), adjusting for age, sex and body mass index (BMI), among adolescents and adults in a population of poor socioeconomic background in India. Data were taken from a cross-sectional study conducted in 2010-2014 among the Limbu community of Darjeeling, West Bengal - an indigenous community with poor socioeconomic background, low literacy rate, low income and inadequate living conditions. The study villages were located in the Himalayan and sub-Himalayan regions of Darjeeling. The present study sample comprised 97 adolescents aged 16-19 years (47 boys, 50 girls) and 260 adults aged 20-39 years (135 men, 125 women). Anthropometric measurements of stature/height (cm), weight (kg), sitting height (cm) and skinfold thicknesses (biceps, triceps, subscapular, suprailiac) (mm) were recorded. Derived variables were BMI (kg/m2), subischial leg length (SLL) (cm), RSLL (%), sum of four skinfolds (mm) and PBF (%). Significant sex differences at p<0.05 were observed for all anthropometric characteristics, except for body weight among adolescents and RSLL, subscapular and sum of four skinfolds in adults. The linear regression models adjusting for age and sex showed that RSLL had a negative relationship with PBF (p<0.05) among adolescents and adults. Higher body fat, independent of BMI, was correlated with lower RSLL among both adolescents and adults from the Limbu community, indicating a possible association with poor quality living conditions in childhood. However, this may also have been due to the allometry of total body fat with body proportions - a relatively larger trunk results in more body fat.

Predictors of maternal-origin microchimerism in young women in the Philippines

OBJECTIVES

Microchimerism is the presence of a small quantity of cells or DNA from a genetically distinct individual. This phenomenon occurs with bidirectional maternal-fetal exchange during pregnancy. Microchimerism can persist for decades after delivery and have long-term health implications. However, little is known about why microchimerism is detectable at varying levels in different individuals. We examine the variability and the following potential determinants of maternal-origin microchimerism (MMc) in young women in the Philippines: gestational duration (in utero exposure to MMc), history of being breastfed (postpartum exposure to MMc), maternal telomere length (maternal cells' ability to replicate and persist), and participant's pregnancies in young adulthood (effect of adding fetal-origin microchimerism to preexisting MMc).

MATERIALS AND METHODS

Data are from the Cebu Longitudinal Health and Nutrition Survey, a population-based study of infant feeding practices and long-term health outcomes. We quantified MMc using quantitative PCR (qPCR) in 89 female participants, ages 20-22, and analyzed these data using negative binomial regression.

RESULTS

In a multivariate model including all predictors, being breastfed substantially predicted decreased MMc (detection rate ratio = 0.15, p = 0.007), and there was a trend of decreasing MMc in participants who had experienced more pregnancies (detection rate ratio = 0.55, p = 0.057).

DISCUSSION

These results might be explained by breastfeeding having lasting impact on immune regulatory networks, thus reducing MMc persistence. MMc may also decrease in response to the introduction of fetal-origin microchimerism with pregnancies experienced in adulthood.

Executive functions form a single construct and are associated with schooling: Evidence from three low- and middle- income countries

Measuring executive function (EF) among adults is important, as the cognitive processes involved in EF are critical to academic achievement, job success and mental health. Current evidence on measurement and structure of EF largely come from Western, Educated, Industrialized, Rich and Democratic (WEIRD) countries. However, measuring EF in low-and-middle-income countries (LMICs) is challenging, because of the dearth of EF measures validated across LMICs, particularly measures that do not require extensive training, expensive equipment, or professional administration. This paper uses data from three LMIC cohorts to test the feasibility, validity and reliability of EF assessment in adults using three sub-tests (representing key components of EF) of the NIH Toolbox Cognitive battery. For each cohort, all three EF measures (inhibition, flexibility and working memory) loaded well onto a unidimensional latent factor of EF. Factor scores related well to measures of fluid intelligence, processing speed and schooling. All measures showed good test-retest reliability across countries. This study provides evidence for a set of sound measures of EF that could be used across different cultural, language and socio-economic backgrounds in future LMIC research. Furthermore, our findings extend conclusions on the structure of EF beyond those drawn from WEIRD countries.

Within-Person Variation in Nutrient Intakes across Populations and Settings: Implications for the Use of External Estimates in Modeling Usual Nutrient Intake Distributions

Determining the proportion of a population at risk of inadequate or excessive nutrient intake is a crucial step in planning and managing nutrition intervention programs. Multiple days of 24-h dietary intake data per subject allow for adjustment of modeled usual nutrient intake distributions for the proportion of total variance in intake attributable to within-individual variation (WIV:total). When only single-day dietary data are available, an external adjustment factor can be used; however, WIV:total may vary by population, and use of incorrect WIV:total ratios may influence the accuracy of prevalence estimates and subsequent program impacts. WIV:total values were compiled from publications and from reanalyses of existing datasets to describe variation in WIV:total across populations and settings. The potential impact of variation in external WIV:total on estimates of prevalence of inadequacy was assessed through simulation analyses using the National Cancer Institute 1-d method. WIV:total values were extracted from 40 publications from 24 countries, and additional values were calculated from 15 datasets from 12 nations. Wide variation in WIV:total (from 0.02 to 1.00) was observed in publications and reanalyses. Few patterns by population characteristics were apparent, but WIV:total varied by age in children (< vs. >1 y) and between rural and urban settings. Simulation analyses indicated that estimates of the prevalence of inadequate intake are sensitive to the selected ratio in some cases. Selection of an external WIV:total estimate should consider comparability between the reference and primary studies with regard to population characteristics, study design, and statistical methods. Given wide variation in observed ratios with few discernible patterns, the collection of ≥2 days of intake data in at least a representative subsample in population dietary studies is strongly encouraged. In the case of single-day dietary studies, sensitivity analyses are recommended to determine the robustness of prevalence estimates to changes in the variance ratio.

Stunting of children under two from repeated pregnancy among young mothers

Repeated pregnancy leaves young mothers nutritionally deprived which may in turn lead to poor infant growth. We measure the occurrence and persistence of stunting among offspring of young mothers who experienced repeated pregnancies using data from the Cebu Longitudinal Health and Nutrition Survey. We selected mothers aged 14-24 years (n = 1,033) with singleton birth. We determined the length-for-age z scores (LAZ) at 12 and 24 months of the index child using the World Health Organisation 2007 growth standard. We fitted LAZ, stunting occurrence (i.e. LAZ < - 2) and persistence from 12 to 24 months into regression models and tested for the mediating effect of low birthweight and feeding practices. In these models, repeated pregnancy was analysed in an ordinal approach using number of past pregnancies of young mothers at birth of the index child. Compared to infants born to young mothers aged 14-24 years who had no previous pregnancies, those born to young mothers with repeated pregnancies have at least 0.15 (95% CI - 0.23, - 0.08) LAZ lower and are at higher chance of stunting by at least 40% (95% CI 1.19, 1.67) at 12 and 24 months. Similar cohorts of infants showed an elevated risk of persistent stunting from 12 through 24 months with a relative risk ratio of 1.51 (95% CI 1.21, 1.88). Optimal feeding practices substantially mediated stunting outcomes by further reducing the effects of repeated pregnancy to stunting occurrence and persistence by 19.95% and 18.09% respectively. Mediation tests also showed low birthweight in the causal pathway between repeated pregnancy and stunting. Repeated pregnancy in young mothers is a predictor of stunting among children under 2 years. Secondary pregnancy prevention measures and addressing suboptimal feeding practices are beneficial to mitigate the negative impact of repeated adolescent pregnancy on children.

Linear growth and mid-childhood cognitive outcomes in three birth cohorts of term-born children: an approach to integrating three growth models to explore critical windows

OBJECTIVE

To illustrate that a mediation framework can help integrate inferences from three growth models to enable a comprehensive view of the associations between growth during specific developmental windows and mid-childhood IQ.

DESIGN

We analysed direct and indirect associations between mid-childhood IQ and length/height growth in five early-life age intervals bounded by conception, birth, early, mid and late infancy, and mid-childhood using estimates from three growth models (lifecourse, conditional change and change score) applied to three historical birth cohorts.

PARTICIPANTS AND SETTING

12 088 term-born children from the Collaborative Perinatal Project (CPP) in the USA (n=2170), the Promotion of Breastfeeding Intervention Trial (PROBIT) in Belarus (n=8275) and the Cebu Longitudinal Health and Nutrition Survey (CLHNS) in the Philippines (n=1643).

PRIMARY OUTCOME MEASURE

Mid-childhood IQ.

RESULTS

Our analyses revealed cross-cohort and cross-interval variations in the direct and indirect effects of foetal and early childhood physical growth on mid-childhood IQ. For example, in CPP, there was a direct association of prenatal growth with IQ that was not evident in the other cohorts, whereas in PROBIT and CLHNS, we observed that foetal and early growth-IQ associations were mediated through size in later periods.

CONCLUSION

Lifecourse, conditional change and change score growth models yield complementary inferences when appropriately interpreted. Future longitudinal studies of associations of early-life growth with later outcomes would benefit from adopting a causal mediation framework to integrate inferences from multiple complementary growth models.

Differential influences of early growth and social factors on young children's cognitive performance in four low-and-middle-income birth cohorts (Brazil, Guatemala, Philippines, and South Africa)

Background

Studies relating childhood cognitive development to poor linear growth seldom take adequate account of social conditions related to both, leading to a focus on nutrition interventions. We aimed to assess the roles of both biological and social conditions in determining early childhood cognition, mediated by birthweight and early linear growth.

Methods

After exploratory structural equation modelling to identify determining factors, we tested direct and indirect paths to cognitive performance through birthweight and child height-for-age at 2 years, assessed between 4 and 8.5 years of age among 2448 children in four birth cohort studies in low-and-middle-income countries (Brazil, Guatemala, Philippines and South Africa). Determinants were compared across the cohorts.

Findings

Three factors yielded excellent fit, comprising birth endowment (primarily maternal age and birth order), household resources (crowding, dependency) and parental capacity (parental education). We estimated their strength together with maternal height in determining cognitive performance. Percentage shares of total effects of the four determinants show a marked transition from mainly biological determinants of birth weight (birth endowment 34%) and maternal height (30%) compared to household resources (25%) and parental capacity (11%), through largely economic determinants of height at 2 years (household resources (60%) to cognitive performance being predominantly determined by parental capacity (64%) followed by household resources (29%). The largely biological factor, birth endowment (maternal age and birth order) contributed only 7% to childhood cognitive performance and maternal height was insignificant. In summary, the combined share of social total effects (household resources and parental capacity) rises from 36∙2% on birth weight, to 78∙2% on height for age at 24 m, and 93∙4% on cognitive functioning.

Interpretation

Across four low- and middle-income contexts, cognition in childhood is influenced more by the parental capacity of families and their economic resources than by birth weight and early linear growth. Improving children's cognitive functioning requires multi-sectoral interventions to improve parental education and enhance their economic wellbeing, interventions that are known to improve also early childhood growth.

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We aimed to investigate separate and combined biological and social determination of young children’s cognitive performance.

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We used path analysis of longitudinal data from birth cohort studies in four differing low-and-middle countries.

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We distinguished biological and social factors, as well as household resources from parental capacity.

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Biological factors determine birthweight, 2-year height depends on social factors, and the latter drive child cognitive performance.

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No single domain intervention provides both necessary and sufficient support for young children’s unfolding development.

A machine learning-based approach for estimating and testing associations with multivariate outcomes

We propose a method for summarizing the strength of association between a set of variables and a multivariate outcome. Classical summary measures are appropriate when linear relationships exist between covariates and outcomes, while our approach provides an alternative that is useful in situations where complex relationships may be present. We utilize machine learning to detect nonlinear relationships and covariate interactions and propose a measure of association that captures these relationships. A hypothesis test about the proposed associative measure can be used to test the strong null hypothesis of no association between a set of variables and a multivariate outcome. Simulations demonstrate that this hypothesis test has greater power than existing methods against alternatives where covariates have nonlinear relationships with outcomes. We additionally propose measures of variable importance for groups of variables, which summarize each groups' association with the outcome. We demonstrate our methodology using data from a birth cohort study on childhood health and nutrition in the Philippines.

Early life stress and HPA axis function independently predict adult depressive symptoms in metropolitan Cebu, Philippines

OBJECTIVES

Alterations in adult hypothalamic-pituitary-adrenal (HPA) axis activity have increasingly been linked with early life stress and adult depression, but a limited number of studies have used longitudinal data to explore HPA axis dysregulation as an underlying mechanism driving the long-term depressive impacts of early stressors. Here we address potential long-term impacts of early life, family-based stress on depressive symptoms among young adults in a longitudinal birth cohort study begun in 1983 in the Philippines.

MATERIALS AND METHODS

We relate a composite measure of family-based stressors experienced between birth and adolescence to circadian dynamics in adult salivary cortisol and depressive risk measured at 21-22 years of age. Multiple regression analyses were conducted to examine the relationship between early life stress levels and risk of adult depressive symptoms, as well as the role of adult diurnal cortisol activity in this relationship.

RESULTS

Greater levels of early life familial stress predicted more severe depressive symptomatology at age 21-22 in a dose-response fashion (p < .0001) independent of adult diurnal cortisol patterns. Flatter diurnal cortisol slopes are directly associated with higher adult depressive symptoms, an effect mostly driven by evening cortisol levels (p = .004). When considering the cumulative effects of early life stress measures, however, exposure to more of these stressors during development is associated with even higher depressive symptoms.

DISCUSSION

The long-term depressive effects of early life familial stress extend to this large sample of Cebuano young adults, and early life stress and HPA axis function may shape adult depressive symptoms through independent pathways in this sample. Our findings provide further evidence that HPA axis activity is shaped by early life conditions and is associated with depressive symptoms.

Otitis media susceptibility and shifts in the head and neck microbiome due to SPINK5 variants

BACKGROUND

Otitis media (OM) susceptibility has significant heritability; however, the role of rare variants in OM is mostly unknown. Our goal is to identify novel rare variants that confer OM susceptibility.

METHODS

We performed exome and Sanger sequencing of >1000 DNA samples from 551 multiethnic families with OM and unrelated individuals, RNA-sequencing and microbiome sequencing and analyses of swabs from the outer ear, middle ear, nasopharynx and oral cavity. We also examined protein localisation and gene expression in infected and healthy middle ear tissues.

RESULTS

A large, intermarried pedigree that includes 81 OM-affected and 53 unaffected individuals cosegregates two known rare A2ML1 variants, a common FUT2 variant and a rare, novel pathogenic variant c.1682A>G (p.Glu561Gly) within SPINK5 (LOD=4.09). Carriage of the SPINK5 missense variant resulted in increased relative abundance of Microbacteriaceae in the middle ear, along with occurrence of Microbacteriaceae in the outer ear and oral cavity but not the nasopharynx. Eight additional novel SPINK5 variants were identified in 12 families and individuals with OM. A role for SPINK5 in OM susceptibility is further supported by lower RNA counts in variant carriers, strong SPINK5 localisation in outer ear skin, faint localisation to middle ear mucosa and eardrum and increased SPINK5 expression in human cholesteatoma.

CONCLUSION

SPINK5 variants confer susceptibility to non-syndromic OM. These variants potentially contribute to middle ear pathology through breakdown of mucosal and epithelial barriers, immunodeficiency such as poor vaccination response, alteration of head and neck microbiota and facilitation of entry of opportunistic pathogens into the middle ear.

Using Systematic Anomalous Case Analysis to Examine Sexual and Reproductive Health Outcomes in the Philippines

The Philippines is characterized by sustained economic growth and political stability, yet sexual and reproductive health indicators have stalled or even worsened in recent decades. We employed an innovative, mixed-methods approach-Systematic Anomalous Case Analysis-to gain insights into these worsening trends by examining sexual and reproductive decision-making among a cohort of young adults in Metro Cebu, Philippines. We first analyzed longitudinal data (1998-2009) to predict reproductive outcomes (i.e., age of first sex, number of living children) among participants in the Cebu Longitudinal Health and Nutrition Survey to identify cases (predicted and anomalous) with whom we subsequently conducted qualitative, in-depth interviews in 2013-14 (n = 48). Analysis of the qualitative data revealed unique social and contextual factors that shaped patterns of sexual and contraceptive decision-making across three, distinct reproductive life stages: (1) at first sex, (2) after the birth of first child, and (3) after the birth of several children. However, gendered roles and expectations exerted strong influences on sexual and reproductive outcomes across these life stages. Finally, we identified two constructs from our qualitative analysis-sexual fluidity and sexual agency-that deserve further examination and integration into theoretical and empirical models of sexual and reproductive decision-making.