Senior Research Scientist, Biology
Inequality in total fertility rates and the proximate determinants of fertility in 21 sub-Saharan African countries
2018; 13 (9): e0203344
View details for DOI 10.1371/journal.pone.0203344
Variation in Anthropometric Status and Growth Failure in Low- and Middle-Income Countries
View details for DOI 10.1542/peds.2017-2183
Ecological and social patterning of child dietary diversity in India: a population-based study
Dietary diversity (DD) measures dietary variation in children. Factors at the child, community, and state levels may be associated with poor child nutritional outcomes. However, few studies have examined the role of macro-level factors on child DD. This study seeks to 1) describe the distribution of child DD in India, 2) examine the variation in DD attributable to the child, community and state levels, and 3) explore the relationship between community socioeconomic context and child DD.Using nationally representative data from children aged 6-23 months in India, multilevel models were used to determine the associations between child DD and individual- and community-level factors.There was substantial variation in child DD score across demographic and socioeconomic characteristics. In an age and sex-only adjusted regression model, the largest portion of variation in child DD was attributable to the child level (75%) while the portions of variance attributable to the community-level and state level were similar to each other (15% and 11%). Including individual-level socioeconomic factors explained 35.6 percent of the total variation attributed to child DD at the community level and 24.8 percent of the total variation attributed to child DD at the state level. Finally, measures of community disadvantage were associated with child DD in when added to the fully adjusted model.This study suggests that both individual and contextual factors are associated with child DD. These results suggest that a population-based approach combined with a targeted intervention for at-risk children may be needed to improve child DD in India.
View details for DOI 10.1016/j.nut.2018.01.006
Distributional change of women's adult height in low- and middle-income countries over the past half century: An observational study using cross-sectional survey data.
2018; 15 (5): e1002568
Adult height reflects childhood circumstances and is associated with health, longevity, and maternal-fetal outcomes. Mean height is an important population metric, and declines in height have occurred in several low- and middle-income countries, especially in Africa, over the last several decades. This study examines changes at the population level in the distribution of height over time across a broad range of low- and middle-income countries during the past half century.The study population comprised 1,122,845 women aged 25-49 years from 59 countries with women's height measures available from four 10-year birth cohorts from 1950 to 1989 using data from the Demographic and Health Surveys (DHS) collected between 1993 and 2013. Multilevel regression models were used to examine the association between (1) mean height and standard deviation (SD) of height (a population-level measure of inequality) and (2) median height and the 5th and 95th percentiles of height. Mean-difference plots were used to conduct a graphical analysis of shifts in the distribution within countries over time. Overall, 26 countries experienced a significant increase, 26 experienced no significant change, and 7 experienced a significant decline in mean height between the first and last birth cohorts. Rwanda experienced the greatest loss in height (-1.4 cm, 95% CI: -1.84 cm, -0.96 cm) while Colombia experienced the greatest gain in height (2.6 cm, 95% CI: 2.36 cm, 2.84 cm). Between 1950 and 1989, 24 out of 59 countries experienced a significant change in the SD of women's height, with increased SD in 7 countries-all of which are located in sub-Saharan Africa. The distribution of women's height has not stayed constant across successive birth cohorts, and regression models suggest there is no evidence of a significant relationship between mean height and the SD of height (β = 0.015 cm, 95% CI: -0.032 cm, 0.061 cm), while there is evidence for a positive association between median height and the 5th percentile (β = 0.915 cm, 95% CI: 0.820 cm, 1.002 cm) and 95th percentile (β = 0.995 cm, 95% CI: 0.925 cm, 1.066 cm) of height. Benin experienced the largest relative expansion in the distribution of height. In Benin, the ratio of variance between the latest and earliest cohort is estimated as 1.5 (95% CI: 1.4, 1.6), while Lesotho and Uganda experienced the greatest relative contraction of the distribution, with the ratio of variance between the latest and earliest cohort estimated as 0.8 (95% CI: 0.7, 0.9) in both countries. Limitations of the study include the representativeness of DHS surveys over time, age-related height loss, and consistency in the measurement of height between surveys.The findings of this study indicate that the population-level distribution of women's height does not stay constant in relation to mean changes. Because using mean height as a summary population measure does not capture broader distributional changes, overreliance on the mean may lead investigators to underestimate disparities in the distribution of environmental and nutritional determinants of health.
View details for DOI 10.1371/journal.pmed.1002568
View details for PubMedID 29750787
Distinct clusters of stunted children in India: An observational study
Maternal and Child Nutrition
Childhood stunting is often conceptualised as a singular concept (i.e., stunted or not), and such an approach implies similarity in the experiences of children who are stunted. Furthermore, risk factors for stunting are often treated in isolation, and limited research has examined how multiple risk factors interact together. Our aim was to examine whether there are subgroups among stunted children, and if parental characteristics influence the likelihood of these subgroups among children. Children who were stunted were identified from the 2005-2006 Indian National Family Health Survey (n = 12,417). Latent class analysis was used to explore the existence of subgroups among stunted children by their social, demographic, and health characteristics. We examined whether parental characteristics predicted the likelihood of a child belonging to each latent class using a multinomial logit regression model. We found there to be 5 distinct groups of stunted children; "poor, older, and poor health-related outcomes," "poor, young, and poorest health-related outcomes," "poor with mixed health-related outcomes," "wealthy and good health-related outcomes," and "typical traits." Both mother and father's educational attainment, body mass index, and height were important predictors of class membership. Our findings demonstrate evidence that there is heterogeneity of the risk factors and behaviours among children who are stunted. It suggests that stunting is not a singular concept; rather, there are multiple experiences represented by our "types" of stunting. Adopting a multidimensional approach to conceptualising stunting may be important for improving the design and targeting of interventions for managing stunting.
View details for DOI 10.1111/mcn.12592
Trends in inequalities in child stunting in South Asia
Maternal & Child Nutrition 2017
2017; e12517: 1-12
View details for DOI 10.1111/mcn.12517
Relative importance of 13 correlates of child stunting in South Asia: Insights from nationally representative data from Afghanistan, Bangladesh, India, Nepal, and Pakistan
Social Science & Medicine
2017; 187: 144-154
View details for DOI 10.1016/j.socscimed.2017.06.017
- Adolescent Fertility and Child Health: The Interaction of Maternal Age, Parity and Birth Intervals in Determining Child Health Outcomes International Journal of Child Health and Nutrition 2017; 6 (1): 16-33
- The Effect of Education on the Demographic Dividend POPULATION AND DEVELOPMENT REVIEW 2016; 42 (4): 651-?
- Association of a Genetic Risk Score With Body Mass Index-Reply. JAMA 2016; 316 (17): 1826-1827
Work-Family Trajectories and the Higher Cardiovascular Risk of American Women Relative to Women in 13 European Countries.
American journal of public health
2016; 106 (8): 1449-1456
To investigate whether less-healthy work-family life histories contribute to the higher cardiovascular disease prevalence in older American compared with European women.We used sequence analysis to identify distinct work-family typologies for women born between 1935 and 1956 in the United States and 13 European countries. Data came from the US Health and Retirement Study (1992-2006) and the Survey of Health, Aging, and Retirement in Europe (2004-2009).Work-family typologies were similarly distributed in the United States and Europe. Being a lone working mother predicted a higher risk of heart disease, stroke, and smoking among American women, and smoking for European women. Lone working motherhood was more common and had a marginally stronger association with stroke in the United States than in Europe. Simulations indicated that the higher stroke risk among American women would only be marginally reduced if American women had experienced the same work-family trajectories as European women.Combining work and lone motherhood was more common in the United States, but differences in work-family trajectories explained only a small fraction of the higher cardiovascular risk of American relative to European women.
View details for DOI 10.2105/AJPH.2016.303264
View details for PubMedID 27310346
Association of a Genetic Risk Score With Body Mass Index Across Different Birth Cohorts
JAMA-JOURNAL OF THE AMERICAN MEDICAL ASSOCIATION
2016; 316 (1): 63-69
Many genetic variants are associated with body mass index (BMI). Associations may have changed with the 20th century obesity epidemic and may differ for black vs white individuals.Using birth cohort as an indicator for exposure to obesogenic environment, to evaluate whether genetic predisposition to higher BMI has a larger magnitude of association among adults from more recent birth cohorts, who were exposed to the obesity epidemic at younger ages.Observational study of 8788 adults in the US national Health and Retirement Study who were aged 50 years and older, born between 1900 and 1958, with as many as 12 BMI assessments from 1992 to 2014.A multilocus genetic risk score for BMI (GRS-BMI), calculated as the weighted sum of alleles of 29 single nucleotide polymorphisms associated with BMI, with weights equal to the published per-allele effects. The GRS-BMI represents how much each person's BMI is expected to differ, based on genetic background (with respect to these 29 loci), from the BMI of a sample member with median genetic risk. The median-centered GRS-BMI ranged from -1.68 to 2.01.BMI based on self-reported height and weight.GRS-BMI was significantly associated with BMI among white participants (n = 7482; mean age at first assessment, 59 years; 3373 [45%] were men; P <.001) and among black participants (n = 1306; mean age at first assessment, 57 years; 505 [39%] were men; P <.001) but accounted for 0.99% of variation in BMI among white participants and 1.37% among black participants. In multilevel models accounting for age, the magnitude of associations of GRS-BMI with BMI were larger for more recent birth cohorts. For example, among white participants, each unit higher GRS-BMI was associated with a difference in BMI of 1.37 (95% CI, 0.93 to 1.80) if born after 1943, and 0.17 (95% CI, -0.55 to 0.89) if born before 1924 (P = .006). For black participants, each unit higher GRS-BMI was associated with a difference in BMI of 3.70 (95% CI, 2.42 to 4.97) if born after 1943, and 1.44 (95% CI, -1.40 to 4.29) if born before 1924.For participants born between 1900 and 1958, the magnitude of association between BMI and a genetic risk score for BMI was larger among persons born in later cohorts. This suggests that associations of known genetic variants with BMI may be modified by obesogenic environments.
View details for DOI 10.1001/jama.2016.8729
View details for Web of Science ID 000379037600019
View details for PubMedID 27380344
Risk factors for chronic undernutrition among children in India: Estimating relative importance, population attributable risk and fractions
SOCIAL SCIENCE & MEDICINE
2016; 157: 165-185
Nearly 40% of the world's stunted children live in India and the prevalence of undernutrition has been persistently high in recent decades. Given numerous available interventions for reducing undernutrition in children, it is not clear of the relative importance of each within a multifactorial framework. We assess the simultaneous contribution of 15 known risk factors for child chronic undernutrition in India. Data are from the 3rd Indian National Family Health Survey (NFHS-3), a nationally representative cross-sectional survey undertaken in 2005-2006. The study population consisted of children aged 6-59 months [n = 26,842 (stunting/low height-for-age), n = 27,483 (underweight/low weight-for-age)]. Risk factors examined for their association with undernutrition were: vitamin A supplementation, vaccination, use of iodized salt, household air quality, improved sanitary facilities, safe disposal of stools, improved drinking water, prevalence of infectious disease, initiation of breastfeeding, dietary diversity, age at marriage, maternal BMI, height, education, and household wealth. Age/sex-adjusted and multivariable adjusted effect sizes (odds ratios) were calculated for risk factors along with Population Attributable Risks (PAR) and Fractions (PAF) using logistic regression. In the mutually adjusted models, the five most important predictors of childhood stunting/underweight were short maternal stature, mother having no education, households in lowest wealth quintile, poor dietary diversity, and maternal underweight. These five factors had a combined PAR of 67.2% (95% CI: 63.3-70.7) and 69.7% (95% CI: 66.3-72.8) for stunting and underweight, respectively. The remaining factors were associated with a combined PAR of 11.7% (95% CI: 6.0-17.4) and 15.1% (95% CI: 8.9-21.3) for stunting and underweight, respectively. Implementing strategies focused on broader progress on social circumstances and infrastructural domains as well as investments in nutrition specific programs to promote dietary adequacy and diversity are required to ensure a long term trajectory of optimal child growth and development in India.
View details for DOI 10.1016/j.socscimed.2015.11.014
View details for Web of Science ID 000375808900020
View details for PubMedID 26625852
Rethinking policy perspectives on childhood stunting: time to formulate a structural and multifactorial strategy.
Maternal and child nutrition
2016; 12: 219-236
Stunting and chronic undernutrition among children in South Asia remain a major unresolved global health issue. There are compelling intrinsic and moral reasons to ensure that children attain their optimal growth potential facilitated via promotion of healthy living conditions. Investments in efforts to ensure that children's growth is not faltered also have substantial instrumental benefits in terms of cognitive and economic development. Using the case of India, we critique three prevailing approaches to reducing undernutrition among children: an over-reliance on macroeconomic growth as a potent policy instrument, a disproportionate focus on interpreting undernutrition as a demand-side problem and an over-reliance on unintegrated single-factorial (one at a time) approaches to policy and research. Using existing evidence, we develop a case for support-led policy approach with a focus on integrated and structural factors to addressing the problem of undernutrition among children in India. Key messages Eliminating child undernutrition is important from an intrinsic perspective and offers considerable instrumental benefits to individual and society. Evidence suggests that an exclusive reliance on a growth-mediated strategy to eliminate stunting needs to be reconsidered, suggesting the need for a substantial support-led strategy. Interpreting and addressing undernutrition as a demand-side problem with proximal single-factorial interventions is futile. There is an urgent need to develop interventions that address the broader structural and upstream causes of child undernutrition.
View details for DOI 10.1111/mcn.12254
View details for PubMedID 27187918
- Improving household-level nutrition-specific and nutrition-sensitive conditions key to reducing child undernutrition in India SOCIAL SCIENCE & MEDICINE 2016; 157: 189-192
Community-Based Health Financing and Child Stunting in Rural Rwanda
AMERICAN JOURNAL OF PUBLIC HEALTH
2016; 106 (1): 49-55
We analyzed the likelihood of rural children (aged 6-24 months) being stunted according to whether they were enrolled in Mutuelles, a community-based health-financing program providing health insurance to rural populations and granting them access to health care, including nutrition services.We retrieved health facility data from the District Health System Strengthening Tool and calculated the percentage of rural health centers that provided nutrition-related services required by Mutuelles' minimum service package. We used data from the 2010 Rwanda Demographic and Health Survey and performed multilevel logistic analysis to control for clustering effects and sociodemographic characteristics. The final sample was 1061 children.Among 384 rural health centers, more than 90% conducted nutrition-related campaigns and malnutrition screening for children. Regardless of poverty status, the risk of being stunted was significantly lower (odds ratio = 0.60; 95% credible interval = 0.41, 0.83) for Mutuelles enrollees. This finding was robust to various model specifications (adjusted for Mutuelles enrollment, poverty status, other variables) or estimation methods (fixed and random effects).This study provides evidence of the effectiveness of Mutuelles in improving child nutrition status and supported the hypothesis about the role of Mutuelles in expanding medical and nutritional care coverage for children.
View details for DOI 10.2105/AJPH.2015.302913
View details for Web of Science ID 000373428000022
View details for PubMedID 26562109
The long-term mortality impact of combined job strain and family circumstances: A life course analysis of working American mothers
SOCIAL SCIENCE & MEDICINE
2015; 146: 111-119
Work stress and family composition have been separately linked with later-life mortality among working women, but it is not known how combinations of these exposures impact mortality, particularly when exposure is assessed cumulatively over the life course. We tested whether, among US women, lifelong work stress and lifelong family circumstances would jointly predict mortality risk.We studied formerly working mothers in the US Health and Retirement Study (HRS) born 1924-1957 (n = 7352). We used sequence analysis to determine five prototypical trajectories of marriage and parenthood in our sample. Using detailed information on occupation and industry of each woman's longest-held job, we assigned each respondent a score for job control and job demands. We calculated age-standardized mortality rates by combined job demands, job control, and family status, then modeled hazard ratios for death based on family constellation, job control tertiles, and their combination.Married women who had children later in life had the lowest mortality risks (93/1000). The highest-risk family clusters were characterized by spells of single motherhood (132/1000). Generally, we observed linear relationships between job control and mortality hazard within each family trajectory. But while mortality risk was high for all long-term single mothers, we did not observe a job control-mortality gradient in this group. The highest-mortality subgroup was previously married women who became single mothers later in life and had low job control (HR 1.91, 95% CI 1.38,2.63).Studies of associations between psychosocial work characteristics and health might consider heterogeneity of effects by family circumstances. Worksite interventions simultaneously considering both work and family characteristics may be most effective in reducing health risks.
View details for DOI 10.1016/j.socscimed.2015.10.024
View details for Web of Science ID 000365370100012
View details for PubMedID 26513120
- Individual and Ecological Variation in Child Undernutrition in India: A Multilevel Analysis JOURNAL OF SOUTH ASIAN DEVELOPMENT 2015; 10 (2): 168-198
Use of Life Course Work-Family Profiles to Predict Mortality Risk Among US Women
AMERICAN JOURNAL OF PUBLIC HEALTH
2015; 105 (4): E96-E102
We examined relationships between US women's exposure to midlife work-family demands and subsequent mortality risk.We used data from women born 1935 to 1956 in the Health and Retirement Study to calculate employment, marital, and parenthood statuses for each age between 16 and 50 years. We used sequence analysis to identify 7 prototypical work-family trajectories. We calculated age-standardized mortality rates and hazard ratios (HRs) for mortality associated with work-family sequences, with adjustment for covariates and potentially explanatory later-life factors.Married women staying home with children briefly before reentering the workforce had the lowest mortality rates. In comparison, after adjustment for age, race/ethnicity, and education, HRs for mortality were 2.14 (95% confidence interval [CI] = 1.58, 2.90) among single nonworking mothers, 1.48 (95% CI = 1.06, 1.98) among single working mothers, and 1.36 (95% CI = 1.02, 1.80) among married nonworking mothers. Adjustment for later-life behavioral and economic factors partially attenuated risks.Sequence analysis is a promising exposure assessment tool for life course research. This method permitted identification of certain lifetime work-family profiles associated with mortality risk before age 75 years.
View details for DOI 10.2105/AJPH.2014.302471
View details for Web of Science ID 000357387800019
View details for PubMedID 25713976
Service availability and association between Mutuelles and medical care usage for under-five children in rural Rwanda: a statistical analysis with repeated cross-sectional data
2015; 5 (9)
To compare the association between Mutuelles enrolment and medical care utilisation among under-five rural children between 2005 and 2010; that is, before and after substantial improvements in service availability took place in rural areas.We tracked the change in service availability between 2005 and 2010. Using the nationally representative population-based Rwanda Demographic and Health Surveys 2005 and 2010, we conducted a statistical analysis using multilevel logistic random-effects models. We included Mutuelles enrollees and uninsured children who had diarrhoea, cough or fever in the previous 2 weeks of the surveys. The final sample size was 4071 children.We observed a substantial increase in the availability of health facilities, medical staff and child health services from 2005 to 2010. In both years, under-five children with Mutuelles were more likely to use medical care than uninsured children. Children in 2010 had a higher probability of using medical care than their counterparts in 2005, regardless of the children's poverty or Mutuelles status. Mutuelles enrollees in 2010 had the highest probability of using care among children in both years. The findings were robust to model specifications and estimation methods.This study suggests the importance of strengthening service provision at the supply side in promoting equitable utilisation of childcare with prepayment schemes.
View details for DOI 10.1136/bmjopen-2015-008814
View details for Web of Science ID 000360863100037
View details for PubMedID 26351188
Economic Inequality and Intergenerational Transfers: Evidence from Mexico.
Journal of the economics of ageing
2015; 5: 23–32
Recent evidence of the National Transfer Accounts (NTA) of Mexico reveals that asset-based reallocations play a significant role in the financing of the expenditures by elderly Mexicans, whereas private and public transfers are used to support most of the expenditures for children. What that evidence does not consider, however, is the fact that differences in socioeconomic status (SES) may seriously distort the reallocation of intergenerational flows. Mexico has long been a country permeated by high levels of inequality, it is then necessary to include its effects in the analysis of intergenerational transfers. Furthermore, age reallocations of economic flows do change over time and such changes might also involve greater economic inequality. In this paper, I assess the effects of SES inequality on the reallocation of intergenerational flows using NTA estimates for two particular years, 1994 and 2004. I show that the reallocation of economic resources, mainly to children and the elderly, by SES changed substantially within this period. The main intergenerational effects associated with SES inequality are: a) equalizing effects of labor income and remittances, b) higher progressivity of public cash and educational transfers, and c) crowding-out effects between private and public transfers among the elderly.
View details for DOI 10.1016/j.jeoa.2014.09.012
View details for PubMedID 26120556
Is low fertility really a problem? Population aging, dependency, and consumption
2014; 346 (6206): 229-234
Longer lives and fertility far below the replacement level of 2.1 births per woman are leading to rapid population aging in many countries. Many observers are concerned that aging will adversely affect public finances and standards of living. Analysis of newly available National Transfer Accounts data for 40 countries shows that fertility well above replacement would typically be most beneficial for government budgets. However, fertility near replacement would be most beneficial for standards of living when the analysis includes the effects of age structure on families as well as governments. And fertility below replacement would maximize per capita consumption when the cost of providing capital for a growing labor force is taken into account. Although low fertility will indeed challenge government programs and very low fertility undermines living standards, we find that moderately low fertility and population decline favor the broader material standard of living.
View details for DOI 10.1126/science.1250542
View details for Web of Science ID 000342721500046
View details for PubMedID 25301626
Changes in memory before and after stroke differ by age and sex, but not by race.
2014; 37 (4): 235-243
Post-stroke memory impairment is more common among older adults, women and blacks. It is unclear whether post-stroke differences reflect differential effects of stroke per se or differences in prestroke functioning. We compare memory trajectories before and after stroke by age, sex and race.Health and Retirement Study participants aged ≥50 years (n = 17,341), with no stroke history at baseline, were interviewed biennially up to 10 years for first self- or proxy-reported stroke (n = 1,574). Segmented linear regression models were used to compare annual rates of memory change before and after stroke among 1,169 stroke survivors, 405 stroke decedents and 15,767 stroke-free participants. Effect modification was evaluated with analyses stratified by baseline age (≤70 vs. >70), sex and race (white vs. nonwhite), and using interaction terms between age/sex/race indicators and annual memory change.Older (>70 years) adults experienced a faster memory decline before stroke (-0.19 vs. -0.10 points/year for survivors, -0.24 vs. -0.13 points/year for decedents, p < 0.001 for both interactions), and among stroke survivors, larger memory decrements (-0.64 vs. -0.26 points, p < 0.001) at stroke and faster memory decline (-0.15 vs. -0.07 points/year, p = 0.003) after stroke onset, compared to younger adults. Female stroke survivors experienced a faster prestroke memory decline than male stroke survivors (-0.14 vs. -0.10 points/year, p < 0.001). However, no sex differences were seen for other contrasts. Although whites had higher post-stroke memory scores than nonwhites, race was not associated with rate of memory decline during any period of time; i.e. race did not significantly modify the rate of decline before or after stroke or the immediate effect of stroke on memory.Older age predicted worse memory change before, at and after stroke onset. Sex and race differences in post-stroke memory outcomes might be attributable to prestroke disparities, which may be unrelated to cerebrovascular disease.
View details for DOI 10.1159/000357557
View details for PubMedID 24686293