Endowments and parental investments in infancy and early childhood

Estimating a Theoretically Consistent Human Capital Production Function With an Application to Head Start

This article describes a conceptual and empirical approach for estimating a human capital production function of child development that incorporates mother- or child-fixed effects. The use of mother- or child-fixed effects is common in this applied economics literature, but its application is often inconsistent with human capital theory. We outline the problem and demonstrate its empirical importance with an analysis of the effect of Head Start and preschool on child and adult outcomes. The empirical specification we develop has broad implications for a variety of applied microeconomic analyses beyond our specific application. Results of our analysis indicate that attending Head Start or preschool had no economically or statistically significant effect on child or adult outcomes.

Adolescents' height and cognitive ability in China

Cognitive ability, as an early human capital, has always been an important research object in modern education and labor economics. Despite growing awareness of the importance of height in individual growth and development, there are few empirical studies on height and cognitive ability. Using the data from the China Education Panel Survey, this paper examined the impact of height on the cognitive ability of adolescents and explored the reasons behind the Chinese pursuit of height growth and the potential impact mechanism. In this paper, comprehensive analysis ability was taken as the representative of cognitive ability. The empirical results showed that height was positively correlated with cognitive ability. From the perspective of the influence mechanism, the hypothesis that height reflected self-esteem, health, non-cognitive ability, and other influences on cognitive ability was excluded. To correct the errors that endogenous problems may cause, we used the PSM method and "age at first menstruation " and "age at first wet dream" as instrumental variables to correct them. The results showed that height still affected cognitive ability, with taller people having higher cognitive ability.

The production of within-family inequality: Insights and implications of integrating genetic data

The integration of genetic data within large-scale social and health surveys provides new opportunities to test long-standing theories of parental investments in children and within-family inequality. Genetic predictors, called polygenic scores, allow novel assessments of young children's abilities that are uncontaminated by parental investments, and family-based samples allow indirect tests of whether children's abilities are reinforced or compensated. We use over 16,000 sibling pairs from the UK Biobank to test whether the relative ranking of siblings' polygenic scores for educational attainment is consequential for actual attainments. We find evidence consistent with compensatory processes, on average, where the association between genotype and phenotype of educational attainment is reduced by over 20% for the higher-ranked sibling compared to the lower-ranked sibling. These effects are most pronounced in high socioeconomic status areas. We find no evidence that similar processes hold in the case of height or for relatives who are not full biological siblings (e.g. cousins). Our results provide a new use of polygenic scores to understand processes that generate within-family inequalities and also suggest important caveats to causal interpretations the effects of polygenic scores using sibling difference designs. Future work should seek to replicate these findings in other data and contexts.

Variation in the Relationship between School Spending and Achievement: Progressive Spending Is Efficient

The equity-efficiency trade-off and cumulative return theories predict larger returns to school spending in areas with higher previous investment in children. Equity-not efficiency-is therefore used to justify progressive school funding: spending more in communities with fewer financial resources. Yet it remains unclear how returns to school spending vary across areas by previous investment. Using county-level panel data for 2009-18 from the Stanford Education Data Archive, the Census Finance Survey, and National Vital Statistics, the authors estimate achievement returns to school spending and test whether returns vary between counties with low and high levels of initial human capital (measured as birth weight), child poverty, and previous spending. Spending returns are higher among counties with low previous investment (counties that also have a high percentage of Black students). Evidence of diminishing returns by previous investment documents another way that schools increase equality and establishes another argument for progressive school funding: efficiency.

Health endowments, schooling allocation in the family, and longevity: Evidence from US twins

We analyze data from the Minnesota Twin Registry (MTR), combined with the Socioeconomic Survey of Twins (SST), and new mortality data, and contribute to two bodies of literature. First, we demonstrate a beneficial causal effect of education on health and longevity in contrast to other twin-based studies of the US population, which show little or no effect of education on health. Second, we present evidence that is consistent with parental compensation through education for differences in their children's endowments that predict health, but find no evidence that parents reinforce differences in endowments that predict earnings. We argue that there is a bias towards detecting reinforcement both in this paper and in the literature. Despite this bias, we still find statistical evidence of compensating behavior. We account for observed and unobserved confounding factors, sample selection bias, and measurement error in education.

Association of sibling presence with language development before early school age among children with developmental delays: A longitudinal study

BACKGROUND/PURPOSE

Having siblings is a crucial ecological factor in children's language development. Whether siblings play a role in the language development of children with developmental delays remains unknown. This study therefore aimed to assess the association between sibling presence and changes in language trajectories of children with developmental delays before reaching early school age.

METHODS

This retrospective cohort-sequential longitudinal study analyzed data from an institution designated by Taiwan's Ministry of Health and Welfare for assessing and identifying young children with developmental delays between December 2008 and February 2016. We included 174 children, aged 10-58 months (mean [standard deviation (SD)], 31.74 [10.15] months), with developmental delays who underwent at least three waves of evaluation. The final evaluation occurred at 37-90 months of age. Data collection spanned over an age from 10 to 90 months. The primary outcome was language delays as determined by board-certified speech-language pathologists.

RESULTS

Of the 174 participants (131 boys), 64.94 % (n = 113) had siblings. The likelihood of both receptive language delay and expressive language delay for participants with siblings increased gradually from 10 to 90 months and exceeded that of participants without siblings, respectively (adjusted odds ratios [aOR], 1.04, 1.04; 95 % confidence interval [CI], 1.01-1.07, 1.01-1.07; P = 0.014, 0.020).

CONCLUSIONS

Having siblings does not necessarily positively associate with language development in children with developmental delays. Clinicians should consider the association of sibling presence with language development for these children in a broader familial-ecological context before they reach early school age.

Parental migrant status and health inequalities at birth: The role of immigrant educational selectivity

Immigrants tend to exhibit better health than natives despite immigrants' more disadvantaged socioeconomic status. This paradox has often been attributed to immigrants' pre-migration selectivity. However, most empirical studies investigating the role of selectivity have focused on adult health; less attention has been paid to children's birth outcomes outside the U.S. context. Using data from the Etude Longitudinale Française depuis l'Enfance (ELFE), a nationally representative sample of over 18000 births in France in 2011, we investigate the role of immigrant parents' educational selectivity in shaping four birth outcomes: birthweight, low birthweight, prematurity, and being born small for gestational age. Results from linear and logistic regressions confirm a health advantage for children of immigrants compared to natives despite lower parental socioeconomic status, mainly among children of Middle Eastern and North African parents. Immigrant parents' positive pre-migration educational selectivity explains most of this health advantage, predominantly among children with two immigrant parents. Further, mediation analyses indicate that the effect of educational selectivity is partially mediated by parental health behaviors, particularly smoking during pregnancy. Furthermore, analyses suggest that selectivity improves birth outcomes only for children of recent arrivals, with less than five years of residence in France. The beneficial effect of selectivity declines with length of residence, suggesting that a process of "unhealthy assimilation," coupled with the cumulative exposure to health risks and disadvantaged living conditions, may lead to the erosion of the protective effect of immigrant selectivity.

The returns to early-life interventions for very low birth weight children

We use comprehensive administrative data from Rhode Island to measure the impact of early-life interventions for low birth weight newborns. Our analysis relies on a regression discontinuity design based on the 1,500 g threshold for Very Low Birth Weight (VLBW) status. We find that threshold crossing causes more intense in-hospital care, in line with prior studies. In terms of later-life outcomes, we show that threshold crossing causes a 0.34 standard deviation increase in test scores in elementary and middle school, a 17.1 percentage point increase in the probability of college enrollment, and a $66,997 decrease in social program expenditures by age 14.

Is there something special about twin families? A comparison of parenting styles in twin and non-twin families

Twin comparisons offer a powerful quasi-experimental design to study the impact of the family of origin on children's life chances. Yet, there are concerns about the generalizability of results obtained from twin studies because twin families are structurally different and twins have a genetic resemblance. We examine these concerns by comparing mothers' reports on their parenting styles for twin and non-twin children between twin and non-twin families, as well as within twin families. We use two German studies for our comparisons: TwinLife and pairfam. Our results demonstrate that twins receive more differential treatment and more emotional warmth than non-twins; however, these differences are largely accounted for by age differences between children. Overall, our results indicate that results on parenting obtained from twin studies can be generalized to non-twin families.

Child Wantedness and Low Weight at Birth: Differential Parental Investment among Roma

Studies investigating child wantedness, birthweight and parental care are limited. This study assessed relationships of child wantedness, low birthweight and differential parental investment in a poor population of Serbian Roma. Data from the Multiple Indicator Cluster Survey round 5 for Roma settlements were used to account for the association between child wantedness and birthweight, and three measures of parental investment: breastfeeding practices, immunization of children and quality of mother-child interaction. The sample included 584 children aged 0-24 months. The child variables were gender, birth order, birthweight (low birthweight at <2500 g and normal birthweight at >2500 g) and whether the child was wanted, while maternal independent variables included age, literacy and household wealth. The results show that unwanted children were at greater risk of having low birthweight. After controlling for birthweight, child wantedness emerged as a predictor of breastfeeding practices and immunization status: Roma mothers biased their investment toward children who were wanted. The quality of mother-child interaction varied with the mother's household wealth. Given the high rates of infant and child mortality among Roma, investments in children's health should be prioritized within the family, where maternal bias in parental investment may contribute to their children's health disparities.

A test of oscillation in the human secondary sex ratio

Background and objectives

The sex ratio of human birth cohorts predicts the health and longevity of their members. Most literature invokes natural selection in support of the argument that heritable tendencies to produce male or female offspring induce oscillation in the sex ratio and its sequelae. Tests of the argument remain exceedingly rare because they require vital statistics describing many generations of a population both unaffected by migration and exposed to an exogenous stressor virulent enough to change the sex ratio at birth. We contribute to the literature by using time-series modeling to detect oscillation in the best data currently available for such a test.

Methodology

We apply rigorous time-series methods to data describing Sweden from 1751 through 1830, a period when the population not only aged in place without migration, but also exhibited the effects of an Icelandic volcanic eruption including a historically low secondary sex ratio. That very low sex ratio should have induced oscillation if heritable mechanisms appear in humans.

Results

We detected oscillation in the ratio but not that predicted by heritable tendencies to produce males or females. We found peak-to-trough oscillation at 14 rather than the approximately 32 years expected from the heritable tendencies argument.

Conclusions and implications

Our findings suggest that mechanisms other than perturbation of heritable tendencies to produce males or females induce oscillation in the human secondary sex ratio. These other mechanisms may include reproductive suppression and selection in utero.

LAY SUMMARY

The male to female ratio in human birth cohorts predicts longevity but its variation over time remains unexplained. We test the long-held theory that the ratio oscillates due to heritable tendencies to produce males or females. We find oscillation, but it appears due to social processes rather than heritable mechanisms.

Twins are more different than commonly believed, but made less different by compensating behaviors

Twin studies are popular, because twins are believed to be the same/similar in genes and environmental exposures. It is well documented, however, that the firstborns are healthier at birth. We use the entire U.S. record of twin births during 1995-2000 to show that the survival duration parameters differ between twins depending on the birth order. We also find that wiser (i.e., older or educated) or married (i.e., resource-richer) mothers take more care of the weaker, which is a "compensating" behavior reducing the twin difference, as opposed to "reinforcing (the twin difference)" behavior. The systematic survival pattern difference and the mother's intervention against nature send cautions to twin studies that regard twins homogeneous to interpret their findings accordingly. Since the survival duration in our data is 97% right-censored in one year, we devise a quantile-based 'fixed-effect' semiparametric estimator that can handle heavy censoring, which is our methodological contribution.

Gestational age, kindergarten-level literacy, and effect modification by maternal socio-economic and demographic factors

BACKGROUND

Shorter gestational age at birth is associated with worse academic performance in childhood. Socio-economic and demographic factors that affect a child's development may modify the relationship between gestational age and later academic performance.

OBJECTIVE

The purpose of this study was to investigate socio-economic and demographic effect modification of gestational age's association with kindergarten-level literacy skills in a longitudinal Wisconsin birth cohort.

METHODS

We sampled 153 145 singleton births (2007-2010) that linked to Phonological Awareness Literacy Screening-Kindergarten (PALS-K) scores (2012-2016 school years). PALS-K outcomes included meeting the screening benchmark (≥28 points, range 0-102 points) and the standardised score. Multivariable linear regressions of PALS-K outcomes on gestational age (completed weeks) included individual interactions for five maternal attributes measured at delivery: Medicaid coverage, education, age, race/ethnicity, and marital status.

RESULTS

Each additional completed gestational week was associated with a 0.5 percentage point increase in the probability of meeting the PALS-K literacy benchmark. The benefit of an additional week of gestational age was 0.5 percentage points (95% confidence interval 0.3, 0.7 percentage points) greater for Medicaid-covered births (0.8 percentage points) relative to non-Medicaid births (0.3 percentage points). Relative to only completing high school, having college education weakened this association by 0.3-0.6 percentage points, depending on years in college. Similar but modest relations emerged with standardised scores.

CONCLUSIONS

Socio-economic advantage as indicated by non-Medicaid coverage or higher levels of completed maternal education may diminish the cost of preterm birth on a child's kindergarten-level literacy skills.

Low birth weight and childhood health: the role of maternal education

PURPOSE

Low birth weight (LBW) is associated with myriad health and developmental problems in childhood and later in life. Less well-documented is the variation in the relationship between LBW status and subsequent child health by socioeconomic status-such as education levels and income. This article examines whether differences exist in the relationship between LBW and subsequent child health by maternal education.

METHODS

We used data from the 1998-2017 National Health Interview Survey to estimate multivariate logistic regression models to determine whether the association between LBW and subsequent child health as measured by general health status, developmental disability, and asthma diagnosis differed by maternal education, net of differences in children's sociodemographic factors, family background, and medical access.

RESULTS

The negative association between LBW and subsequent health was typically weaker for children of mothers with less than high school education than it was for children of mothers with higher levels of education.

CONCLUSIONS

The findings on the enduring impact of LBW status on child health for all children, especially those born to mothers with higher levels of education, suggest that all children born LBW should be provided appropriate medical and support services to reduce the lifelong repercussions of poor health at birth.

How does birth weight affect health and human capital? A short- and long-term evaluation

In utero shocks have been shown to have long-lasting consequences. However, we hardly know whether these effects tend to fade out over time and whether they can be compensated by post-natal investments. This paper examines the effect of birth endowment over time by employing a long panel of individuals born in 1983 in Cebu (Philippines) that includes relevant information on the pregnancy. We build a refined health endowment measure netted out from prenatal investments. We find that initial endowments affect trajectories both through the human capital production function and subsequent parental investment. The effect of birth endowment remains until adulthood and the fading out is very limited for health outcomes but more pronounced for educational outcomes. We also find that parents tend to reinforce initial health endowments, but the effect of this behaviour has almost no effect on final outcomes.

Associations Among Mothers' Depression, Emotional and Learning-Material Support to Their Child, and Children's Cognitive Functioning: A 16-Year Longitudinal Study

This study examined the associations among maternal depression, mothers' emotional and material investment in their child, and children's cognitive functioning. Middle-class Chilean mothers and children (N = 875; 52% males) were studied when children were 1, 5, 10, and 16 years (1991-2007). Results indicated that highly depressed mothers provided less emotional and material support to their child across all ages, which related to children's lower IQ. Children with lower mental abilities at age 1 received less learning-material support at age 5, which led to mothers' higher depression at child age 10. Mothers' low support was more strongly linked to maternal depression as children got older. Findings elucidate the dynamic and enduring effects of depression on mothers' parenting and children's development.

Birth Weight and Early Cognitive Skills: Can Parenting Offset the Link?

Objectives There is an enduring negative association between low birth weight (<2500 g) and early childhood cognitive skills. This study examines if parenting practices meaningfully contribute to or offset birth weight disparities in cognitive development prior to formal schooling. Methods This study uses the ECLS-B, a nationally representative sample of live births in the United States in 2001. Unlike studies focused on one or two measures of parenting and investment, this study considers a wide array parenting measures collected at multiple time points, tracked from before birth across 5 years of development. Results Regression results show that nearly 50 % of the low-birth-weight gap in early math and reading ability is associated with family socioeconomic status. Between-family OLS regressions show that parenting practices, including "parental interaction," "cognitive stimulation," and "parent quality", are negatively associated with low birth weight and positively associated with improved cognitive skill among all children. After adjustment for family socioeconomic status, parenting practices did little to offset (by mediation or moderation) remaining birth weight disparities in early cognitive development. Conclusions Effective parenting is positively associated with cognitive development, but parenting is not a panacea-the developmental disadvantages associated with poor child health are not linked to parenting practices. We argue that birth weight disparities are rooted in biology and cannot easily be offset by parenting practices.

Missing Time with Parents: Son Preference among Asians in the United States

We study prevalence of son preference in families of East and South Asian origin living in the U.S. by investigating parental time investments in children using American Time Use Surveys. Estimates show that East and South Asian mothers spend an additional hour of quality time per day with their young (aged 0-2 years) sons than with young daughters; son-preference in mothers' time allocation declines as children get older. East and South Asian fathers' time with young children is gender neutral. We find gender specialization in time with children aged 6-17 with fathers spending more time with sons and mothers spending more time with daughters.

Parental preferences and allocations of investments in children's learning and health within families

Empirical evidence suggests that parental preferences may be important in determining investment allocations among their children. However, there is mixed or no evidence on a number of important related questions. Do parents invest more in better-endowed children, thus reinforcing differentials among their children? Or do they invest more in less-endowed children to compensate for their smaller endowments and reduce inequalities among their children? Does higher maternal education affect the preferences underlying parental decisions in investing among their children? What difference might such intrafamilial investments among children make? And what is the nature of these considerations in the very different context of developing countries? This paper gives new empirical evidence related to these questions. We examine how parental investments affecting child education and health respond to initial endowment differences between twins within families, as represented by birth weight differences, and how parental preference tradeoffs and therefore parental investment strategies vary between families with different maternal education. Using the separable earnings-transfers model (Behrman et al., 1982), we first illustrate that preference differences may make a considerable difference in the ratios of health and learning differentials between siblings - up to 30% in the simulations that we provide. Using a sample of 2000 twins, collected in the 2012 wave of the Early Childhood Longitudinal Survey for Chile, we find that preferences are not at the extreme of pure compensatory investments to offset endowment inequalities among siblings nor at the extreme of pure reinforcement to favor the better-endowed child with no concern about inequality. Instead, they are neutral, so that parental investments do not change the inequality among children due to endowment differentials. We also find that there are not significant preference differences between families with low- and high-educated mothers. Our estimates are consistent with previous empirical evidence that finds that parents do not invest differentially within twins.

Familial transient financial difficulties during infancy and long-term developmental concerns

BACKGROUND

Socioeconomic difficulties affect the cognitive and emotional development of children. However, the focus of prior studies has largely been on poverty and material hardship. This study expands on the existing literature by examining the impact of familial transient financial difficulties during infancy on long-term cognitive and behavioral outcomes.

METHODS

The National Longitudinal Surveys of Youth (79) were used to assess the association between a transient drop in family income by 50% or more (called transient income decline or TID) during the first 3 years of life and later-life Peabody Individual Achievement Math and Reading scores and behavior problem index (BPI) scores (N = 8272-17 348; median assessment age = 9 years). A subsample of matched siblings (N = 2049-4238) was examined to tease out maternal and intra-familial effects.

RESULTS

Exposure to TID predicted increased total and externalizing BPI scores (std. coefficients of 0.10 and 0.09, respectively, p < 0.01) in the overall sample. Among matched siblings, exposure to TID predicted increased total, externalizing, and internalizing BPI scores (std. coefficients of 0.27, 0.25, and 0.23, respectively, p < 0.01).

CONCLUSION

Familial transient financial difficulties can have long-lasting behavioral effects for infants. The study identifies an early risk factor and at-risk children, thus providing insight into developing early intervention measures for infants to avoid long-term behavioral problems.

The Short-Run and Long-Run Effects of Birth Weight: Evidence from Large Samples of Siblings and Twins in Taiwan

In this paper, we assemble five large administrative data sets in Taiwan to investigate the short-run and long-run effects of birth weight. Comparing with previous studies, our results are more precisely estimated due to the large sample size. Using administrative data sets, the problems arising from self-reported samples are also mitigated. Moreover, we are able to examine both singletons by controlling sibling fixed effects and twins by controlling twin fixed effects. Our results show that an infant's birth weight has positive influence on health and education. Our twin fixed-effects estimates confirm the finding of a long-lasting, but diminishing in the longer run, effects of birth weight. Copyright © 2016 John Wiley & Sons, Ltd.

The Roles of Fathers' Involvement and Coparenting in Relationship Quality among Cohabiting and Married Parents

Relationship quality often declines following the birth of child, likely reflecting in part the shift towards role traditionalization that occurs through gender specialization. The current study used longitudinal data from the Fragile Families and Child Well-Being Study, an urban birth cohort in 2000 consisting of structured interviews of mothers and fathers who were followed over 5 years (n=1275), to examine whether low levels of fathers' involvement and coparenting, two indicators of role traditionalization, were linked to negative trajectories of mothers' and fathers' relationship quality for couples whose first child was born in marriage or cohabitation. We carefully consider union transitions in the 5 years postpartum by including between-subjects variables indicating that the parents were continually married, continually cohabiting, were cohabiting at the child's birth and got married after, or were cohabiting or married at the child's birth but subsequently separated. As anticipated, both fathers' involvement and coparenting were positively associated with parents' reports of relationship quality, more so for mothers than for fathers and especially for cohabiting mothers, buffering the decline in mothers' and fathers' relationship quality that typically accompanies the birth of a child. These findings underscore the importance of the father role, not only for the well-being of the child (as we know from other research) but also for the relationship of the parents. Fathers should be encouraged and supported to take an active role in parenting through educational programs and public policy (e.g., paid paternity leave).

Compensation or Reinforcement? The Stratification of Parental Responses to Children’s Early Ability

Theory and empirical evidence suggest that parents allocate their investments unequally among their children, thus inducing within-family inequality. We investigate whether parents reinforce or compensate for initial ability differences between their children as well as whether these parental responses vary by family socioeconomic status (SES). Using the Early Childhood Longitudinal Study, Birth Cohort (ECLS-B) and a twin fixed-effects approach to address unobserved heterogeneity, we find that parental responses to early ability differences between their children do vary by family SES. Contrary to prior findings, we find that advantaged parents provide more cognitive stimulation to higher-ability children, and lower-class parents do not respond to ability differences. No analogous stratification in parental responses to birth weight is found, suggesting that parents’ responses vary across domains of child endowments. The reinforcing responses to early ability by high-SES parents do not, however, led to increases in ability differences among children because parental responses have little effect on children’s later cognitive performance in this twin sample.

Endowments at Birth and Parents' Investments in Children

Do parents invest more in higher quality children, or do they compensate for lower quality by giving more to children with lower endowments? We answer this question in the context of a large-scale iodine supplementation programme in Tanzania. We find that children with higher programme exposure were more likely to receive necessary vaccines and were breastfed for longer. Siblings of treated children were also more likely to be immunised. Fertility behavior and investments at the time of birth were unaffected.

Are natural disasters in early childhood associated with mental health and substance use disorders as an adult?

Understanding factors that influence risk for mental health and substance use disorders is critical to improve population health and reduce social costs imposed by these disorders. We examine the impact of experiencing a natural disaster-a serious fire, tornado, flood, earthquake, or hurricane-by age five on adult mental health and substance use disorders. The analysis uses data from the 2004 to 2005 National Epidemiologic Survey of Alcohol and Related Conditions. The analysis sample includes 27,129 individuals ages 21-64 years. We also exploit information on parenting strategies to study how parents respond to natural disasters encountered by their children. We find that experiencing one or more of these natural disasters by age five increases the risk of mental health disorders in adulthood, particularly anxiety disorders, but not substance use disorders. Parents alter some, but not all, of their parenting strategies following a natural disaster experienced by their children. It is important to provide support, for example through counseling services and financial assistance, to families and children exposed to natural disasters to mitigate future mental health and substance use problems attributable to such exposure.

Health and the Economy in the United States, from 1750 to the Present

I discuss the health transition in the United States, bringing new data to bear on health indicators, and investigating the changing relationship between health, income, and the environment. I argue that scientific advances played an outsize role and that health improvements were largest among the poor. Health improvements were not a precondition for modern economic growth. The gains to health are largest when the economy has moved from "brawn" to "brains" because this is when the wage returns to education are high, leading the healthy to obtain more education. More education may improve use of health knowledge, producing a virtuous cycle.

When children affect parents: Children's academic performance and parental investment

Sociologists have extensively documented the ways that parent resources predict children's achievement. However, less is known about whether and how children's academic performance shapes parental investment behaviors. I use data from the Early Childhood Longitudinal Study-Kindergarten Cohort (ECLS-K) and longitudinal fixed effects models to examine how changes in teacher assessments are related to changes in the conferral of various parent resources. Overall, I find that the relationship between achievement and investment varies based on the directionality in children's achievement and the type of resource at hand. Children whose performance improves receive a broad range of enrichment resources, while declines in performance are met with corrective educational resources. Results are largely consistent whether language or math assessments are used to predict investment, and also among children whose achievement does not change over time. I discuss these patterns, along with implications for the use of parent resources in education and family research.

Breastfeeding over two years is associated with longer birth intervals, but not measures of growth or health, among children in Kilimanjaro, TZ

OBJECTIVES

Breastfeeding has been associated with numerous health and well-being benefits for both children and their mothers, including prolonging the birth interval to the subsequent sibling. The clearest associations between breastfeeding and health outcomes, per se, reflect exclusive breastfeeding in the first months of postnatal life and are most evident during infancy. Fewer studies explore the consequences of breastfeeding for multiple years. In this article, we ask whether breastfeeding for more than 2 years is associated with discernible health and well-being benefits to children.

METHODS

Data were collected from 315 children, aged 2 to 7, and their caretakers residing in Kilimanjaro, Tanzania. Basic demographic and health information was solicited, and anthropometric and blood markers of health were evaluated.

RESULTS

Our results indicate a strong positive relationship between breastfeeding for 2 or more years and interbirth interval, but little evidence for a relationship between prolonged breastfeeding and several indicators of child growth and health.

CONCLUSIONS

We suggest that these relationships may support the recently rekindled birth spacing hypothesis, positing selection for longer interbirth intervals, rather than, or in addition to, more direct health benefits associated with breastfeeding for 2 or more years. Our results may indicate attenuating health benefits associated with longer breastfeeding.

Understanding heterogeneity in the effects of birth weight on adult cognition and wages

A large economics literature has shown long term impacts of birth weight on adult outcomes, including IQ and earnings that are often robust to sibling or twin fixed effects. We examine potential mechanisms underlying these effects by incorporating findings from the genetics and neuroscience literatures. We use a sample of siblings combined with an "orchids and dandelions hypothesis", where the IQ of genetic dandelions is not affected by in utero nutrition variation but genetic orchids thrive under advantageous conditions and wilt in poor conditions. Indeed, using variation in three candidate genes related to neuroplasticity (APOE, BDNF, and COMT), we find substantial heterogeneity in the associations between birth weight and adult outcomes, where part of the population (i.e., "dandelions") is not affected by birth weight variation. Our results help uncover why birth weight affects adult outcomes.

Geographic Effects on Intergenerational Income Mobility

The notion that where one grows up affects future living standards is increasingly well established in social science. Yet research on intergenerational economic mobility often ignores the regional and neighborhood context of childhood, especially local purchasing power. We hypothesize that unexplained variation in intergenerational mobility is partly attributable to regional and neighborhood conditions-most notably access to high quality schools. Using the Panel Study of Income Dynamics and other data, we find that neighborhood income has roughly half the effect on future earnings as parental income and roughly the same effect as shared sibling characteristics. Growing up in an economically segregated metropolitan area also has a large negative effect on future earnings, though somewhat smaller than the neighborhood effect. We estimate that lifetime household income would be $500,000 dollars higher if people born into a bottom quartile neighborhood would have been raised in a top quartile neighborhood. These results are robust to considerations of regional purchasing power and migration between metro areas. Finally, we replicate the results for economic segregation at the metropolitan level using aggregated metropolitan level statistics of intergenerational income elasticities based on millions of IRS records.

Birth weight and academic achievement in childhood

Research has shown that birth weight has a lasting impact on later-life outcomes such as educational attainment and earnings. This paper examines the role of health at birth in determining academic achievement in childhood, which may provide the link between birth weight and adult outcomes. Using three waves of the Child Development Supplement of the Panel Study of Income Dynamics data over 1997-2007, we build on the literature by employing the fetal growth rate as a proxy for net nutritional intake in utero and propose a nested error-component two-stage least squares estimator that draws on internal instruments from alternative dimensions of the multilevel panel data set. In particular, this alternative estimator allows us to exploit the information on children with no siblings in the sample, which comprise over 40% of the observations in our sample, as well as to obtain coefficient estimates for the time-invariant variables such as race and maternal education. This would not be feasible with the usual mother fixed effects estimation. We obtain modest but significant effects of both birth weight and the fetal growth rate on math and reading scores, with the effects concentrated in the low birth weight range. Infant health measures appear to explain little of the well-documented racial disparity in test scores.

Family investment responses to childhood health conditions: intrafamily allocation of resources

The onset of a health condition during childhood impairs skill formation. A number of studies have investigated the long-lasting effects of poor health during childhood on later-in-life outcomes. However, this evidence ignores how parents respond to the onset of health conditions. Do their investments reinforce the health condition? Or compensate, or behave neutrally? If parents change their investments, the relationship between early health and later outcomes combines the biological effect and the investment responses. To address this question, I use within-sibling variation in the incidence of health conditions to control for selection from unobserved household heterogeneity. Parents invest, on average, 0.16 standard deviations less in children with mental conditions relative to their healthy siblings, using a measure of investment that includes time and resources. On the contrary, when children have a physical condition, parental investments do not differ across siblings. Results are robust to alternative measures of health conditions and the inclusion of child fixed effects.

Intrahousehold resource allocation: do parents reduce or reinforce child ability gaps?

Do parents invest more or less in their high-ability children? We provide new evidence on this question by comparing observed ability differences and observed investment differences between siblings living in the United States. To overcome endogeneity issues, we use sibling differences in handedness as an instrument for cognitive ability differences. We find that parents invest more in high-ability children, with a 1 standard deviation increase in child cognitive ability increasing parental investments by approximately one-third of a standard deviation. Consequently, differences in child cognitive ability are enhanced by differential parental investments.

The evolutionary ecology of early weaning in Kilimanjaro, Tanzania

Public health recommendations promote prolonged breastfeeding of all children; however, parental investment (PI) theory predicts that breastfeeding will be allocated among a mothers' offspring to maximize her reproductive success. We evaluated PI in terms of risk for weaning before age two among 283 children in Kilimanjaro, Tanzania. Results demonstrate: (i) a Trivers-Willard effect--high socioeconomic status (SES) females and low SES males were more likely to be weaned early; (ii) later-born children were less likely to be weaned early; (iii) higher birthweight children were less likely to be weaned early, and (iv) no effect of cattle (a source of supplementary milk) ownership. These associations were largely independent and remained significant in models controlling for potential confounders; however, the inverse association between early weaning and birth order lost significance in the model containing birthweight. These patterns were observed despite public health recommendations encouraging breastfeeding for at least two years.

Is biology destiny? Birth weight and differential parental treatment

Time diaries of sibling pairs from the PSID-CDS are used to determine whether maternal time investments compensate for or reinforce birth-weight differences among children. The findings demonstrate that the direction and degree of differential treatment vary by mother's education. Less-educated mothers devote more total time and more educationally oriented time to heavier-birth-weight children, whereas better-educated mothers devote more total and more educationally oriented time to lower-birth-weight children. The compensating effects observed among highly educated mothers are substantially larger than the reinforcing effects among the least-educated mothers. The findings show that families redistribute resources in ways that both compensate for and exacerbate early-life disadvantages.

A novel quantitative approach to women's reproductive strategies

The patterned way in which individuals allocate finite resources to various components of reproduction (e.g. mating effort, reproductive timing and parental investment) is described as a reproductive strategy. As energy is limited, trade-offs between and within aspects of reproductive strategies are expected. The first aim of this study was to derive aspects of reproductive strategies using complete reproductive histories from 718 parous Western Australian women. Factor analysis using a subset of these participants resulted in six factors that represented 'short-term mating strategy', 'early onset of sexual activity', 'reproductive output', 'timing of childbearing', 'breastfeeding', and 'child spacing'. This factor structure was internally validated by replication using a second independent subset of the data. The second aim of this study examined trade-offs between aspects of reproductive strategies derived from aim one. Factor scores calculated for each woman were incorporated in generalised linear models and interaction terms were employed to examine the effect of mating behaviour on the relationships between reproductive timing, parental investment and overall reproductive success. Early sexual activity correlates with early reproductive onset for women displaying more long-term mating strategies. Women with more short-term mating strategies exhibit a trade-off between child quantity and child quality not observed in women with a long-term mating strategy. However, women with a short-term mating strategy who delay reproductive timing exhibit levels of parental investment (measured as breastfeeding duration per child) similar to that of women with long-term mating strategies. Reproductive delay has fitness costs (fewer births) for women displaying more short-term mating strategies. We provide empirical evidence that reproductive histories of contemporary women reflect aspects of reproductive strategies, and associations between these strategic elements, as predicted from life history theory.

Childhood circumstances and the intergenerational transmission of socioeconomic status

A large literature has documented the intergenerational transmission of socioeconomic status (SES). However, the mechanisms by which SES transmits across generations are still little understood. This article investigates whether characteristics determined in childhood play an important role in the intergenerational transmission. Using data from the Cebu Longitudinal Health and Nutrition Survey, I document the extent to which childhood human capital accounts for the intergenerational SES correlation. My results imply that childhood health and nutrition, cognitive and noncognitive abilities, and early schooling account for between one-third and one-half of the relationship between parents' SES and their offspring's SES.

Early life exposure to malaria and cognition in adulthood: evidence from Mexico

This study examines the impact of early life malaria exposure on cognition in sample of Mexican adults, using the nationwide introduction of malaria eradication efforts to identify causal impacts. The core findings are that birth year exposure to malaria eradication was associated with increases in Raven Progressive Matrices test scores and consumption expenditures, but not schooling. Additionally, cohorts born after eradication both entered and exited school earlier than their pre-eradication counterparts. These effects were only seen for men and explanations for this are assessed. Collectively, these findings suggest that improvements in infant health help explain secular increases in cognitive test scores, that better cognition may link early life health to adulthood earnings, and that human capital investments through childhood and young adulthood respond sensitively to market returns to early life endowment shocks.

Prenatal Health, Educational Attainment, and Intergenerational Inequality: The Northern Finland Birth Cohort 1966 Study

In this article, we study the effects of prenatal health on educational attainment and on the reproduction of family background inequalities in education. Using Finnish birth cohort data, we analyze several maternal and fetal health variables, many of which have not been featured in the literature on long-term socioeconomic effects of health despite the effects of these variables on birth and short-term health outcomes. We find strong negative effects of mother’s prenatal smoking on educational attainment, which are stronger if the mother smoked heavily but are not significant if she quit during the first trimester. Anemia during pregnancy is also associated with lower levels of attained education. Other indicators of prenatal health (pre-pregnancy obesity, mother’s antenatal depressed mood, hypertension and preeclampsia, early prenatal care visits, premature birth, and small size for gestational age) do not predict educational attainment. Our measures explain little of the educational inequalities by parents’ class or education. However, smoking explains 12%—and all health variables together, 19%—of the lower educational attainment of children born to unmarried mothers. Our findings point to the usefulness of proximate health measures in addition to general ones. They also point to the potentially important role played by early health in intergenerational processes.

The effect of birthweight on childhood cognitive development in a middle-income country

BACKGROUND

Intra-uterine growth is a powerful predictor of infant mortality and of health, developmental and socioeconomic outcomes in adulthood. The question about whether this relationship is causal rather than driven by unobserved characteristics of low-weight infants is, however, still open. We use twin models to examine the hypothesis that in utero growth has a detrimental impact on cognitive development in childhood.

METHODS

We merge birth registry information on birthweight with standardized Math and Spanish test scores for all fourth graders in Chile to create a prospective data set. Twin fixed-effects models are used to estimate the causal effect of intra-uterine growth on test scores. Fixed-effect estimates are compared with traditional regression results in a cross-section of births to gauge the omitted variable bias emerging from unobserved genetic, maternal and pregnancy-related factors in cross-sectional models.

RESULTS

Birthweight differences within twin pairs have a substantial effect on test scores. A 400-g increase in birthweight results in a 15% standard deviation increase in Math scores. The effect is larger among (estimated) monozygotic than dizygotic pairs, reaching >20% standard deviation. The effect varies across family socioeconomic status. It is strong among disadvantaged families but it nearly disappears among advantaged ones.

CONCLUSION

Scarcity of uterine resources resulting in intra-uterine growth restriction has a detrimental effect on cognitive development in childhood. This effect interacts with family socioeconomic status (SES), so that low-SES families reinforce the effect of low birthweight and high-SES families fully compensate for it. Findings are particularly relevant in the developing world, where intra-uterine growth restriction is the main determinant of low birthweight.

Killing Me Softly: The Fetal Origins Hypothesis

In the epidemiological literature, the fetal origins hypothesis associated with David J. Barker posits that chronic, degenerative conditions of adult health, including heart disease and type 2 diabetes, may be triggered by circumstance decades earlier, in utero nutrition in particular. Economists have expanded on this hypothesis, investigating a broader range of fetal shocks and circumstances and have found a wealth of later-life impacts on outcomes including test scores, educational attainment, and income, along with health. In the process, they have provided some of the most credible observational evidence in support of the hypothesis. The magnitude of the impacts is generally large. Thus, the fetal origins hypothesis has not only survived contact with economics, but has flourished.

Infant health, race/ethnicity, and early educational outcomes using the ECLS-B

Using data from the "Early Childhood Longitudinal Study—Birth Cohort," this article emphasizes the central role of poor infant health as a mechanism in the formation of early educational disparities. Results indicate that the varying prevalence of poor infant health across racial/ethnic groups explains a significant portion of the black disadvantage and a moderate portion of the Asian advantage relative to whites in math and reading skills at age four. Results also demonstrate that infant health is an equal opportunity offender across social groups as children with poor health are equally disadvantaged in terms of early cognitive development, regardless of racial/ethnic status. Overall, results indicate that health at birth has important consequences for individual educational achievement and racial/ethnic disparities in cognitive development and school readiness.