Why Is Infant Mortality Higher in Boys Than in Girls?

Why Is Infant Mortality Higher in Boys Than in Girls? A New Hypothesis Based on Preconception Environment and Evidence From a Large Sample of Twins

Roland Pongou

Demography
November 2012

Abstract

Infant mortality is higher in boys than girls in most parts of the world. This has been explained by sex differences in genetic and biological makeup, with boys being biologically weaker and more susceptible to diseases and premature death. At the same time, recent studies have found that numerous preconception or prenatal environmental factors affect the probability of a baby being conceived male or female. I propose that these environmental factors also explain sex differences in mortality. I contribute a new methodology of distinguishing between child biology and preconception environment by comparing male-female differences in mortality across opposite-sex twins, same-sex twins, and all twins. Using a large sample of twins from sub-Saharan Africa, I find that both preconception environment and child biology increase the mortality of male infants, but the effect of biology is substantially smaller than the literature suggests. I also estimate the interacting effects of biology with some intrauterine and external environmental factors, including birth order within a twin pair, social status, and climate. I find that a twin is more likely to be male if he is the firstborn, born to an educated mother, or born in certain climatic conditions. Male firstborns are more likely to survive than female firstborns, but only during the neonatal period. Finally, mortality is not affected by the interactions between biology and climate or between biology and social status.

http://link.springer.com/article/10.1007/s13524-012-0161-5

Early-Life Health and Adult Circumstance in Developing Countries

Early-Life Health and Adult Circumstance in Developing Countries

Janet Currie, Tom Vogl

NBER Working Paper No. 18371
Issued in September 2012
NBER Program(s):   AG   CH   HC   HE   LS

A growing literature documents the links between long-term outcomes and health in the fetal period, infancy, and early childhood. Much of this literature focuses on rich countries, but researchers are increasingly taking advantage of new sources of data and identification to study the long reach of childhood health in developing countries. Health in early life may be a more significant determinant of adult outcomes in these countries because health insults are more frequent, the capacity to remediate is more limited, and multiple shocks may interact. However, the underlying relationships may also be more difficult to measure, given significant mortality selection. We survey recent evidence on the adult correlates of early-life health and the long-term effects of shocks due to disease, famine, malnutrition, pollution, and war.

http://www.princeton.edu/~tvogl/currie_vogl_AR.pdf

Traffic Congestion and Infant Health: Evidence from E-ZPass

Traffic Congestion and Infant Health: Evidence from E-ZPass
Janet Currie and Reed Walker
American Economic Journal: Applied Economics, 3(1): 65–90.

Abstract
We exploit the introduction of electronic toll collection, (E-ZPass), which greatly reduced both traffic congestion and vehicle emissions near highway toll plazas. We show that the introduction of E-ZPass reduced prematurity and low birth weight among mothers within 2 kilometers (km) of a toll plaza by 10.8 percent and 11.8 percent, respectively, relative to mothers 2-10 km from a toll plaza. There were no immediate changes in the characteristics of mothers or in housing prices near toll plazas that could explain these changes. The results are robust to many changes in specification and suggest that traffic congestion contributes significantly to poor health among infants. (JEL I12, J13, Q51, Q53, R41)

http://www.columbia.edu/~rw2157/research/CurrieWalker_EZPass_2011.pdf

Heights and human welfare: Recent developments and new directions

Heights and human welfare: Recent developments and new directions
Steckel, R.H.
Special Issue on Heights and Human Welfare
Explorations in Economic History, Volume 46, Issue 1, January 2009, Pages 1-23

Abstract

Since 1995 approximately 325 publications on stature have appeared in the social sciences, which is more than a four-fold increase in the rate of production relative to the period 1977-1994. The expansion occurred in several areas, but especially within economics, indicating that heights are now widely accepted as useful measure of human welfare. Much of this new work extends beyond the traditional bailiwick of anthropometric history, including biological welfare during economic and political crises; anthropometric determinants of wages; the welfare of women relative to men in the contemporary world; the fetal origins hypothesis; and inequality in the developing world. The approach has also expanded within economic history to consider the consequences of empire for colonials; the health of populations lacking traditional measures of social performance; the consequences of smallpox; and very long-term trends in health. Much has also been learned about socioeconomic aspects of inequality, the welfare implications of industrialization, and socioeconomic determinants of stature. The last is a work in progress and one may doubt whether sufficient longitudinal evidence will become available for a complete understanding of the variety and strength of pathways that affect human physical growth. 

 

Ungated Version:

http://cid.bcrp.gob.pe/biblio/Papers/NBER/2008/diciembre/w14536.pdf

Investing in Health to Improve the Wellbeing of the Disadvantaged: Reversing the Argument of the Marmot Reports

Investing in Health to Improve the Wellbeing of the Disadvantaged: Reversing the Argument of the Marmot Reports

David Canning and Diana Bowser
Social Science & Medicine
Volume 71, Issue 7, October 2010, Pages 1223–1226

Abstract

The Marmot reports have argued that health inequalities are the result of social inequalities. They advocate reducing health inequalities by undertaking fundamental changes that make society fairer. We argue that the focus should be on improving the health and wellbeing of the disadvantaged, even if the policies that do this also raise the health of the better off, and worsen inequality. We also argue that the causality runs from health to social status, and that health interventions are needed to improve socioeconomic outcomes. While we disagree on goals and mechanisms we are in surprisingly close agreement with Marmot Reports on policies. In particular, we agree with the focus on in early childhood investments in health and physical and cognitive development that have long term socioeconomic payoffs. We also endorse making society fairer, though mainly as a goal in itself rather than an instrument to reduce health inequality.

Keywords: Health gradient; Social inequality; Social determinants of health; Fair Society, Healthy Lives (The Marmot Review)

Ungated Version

New IZA Working Paper: The Effects of World War II on Economic and Health Outcomes across Europe

IZA DP No. 6296

Iris Kesternich, Bettina Siflinger, James P. Smith, Joachim K. Winter:

The Effects of World War II on Economic and Health Outcomes across Europe

Abstract:
In this paper, we investigate the long-run effects of World War II on socio-economic status (SES) and health of older individuals in Europe. Physical and psychological childhood events are important predictors for labor market and health outcomes in adult life, but studies that quantify these effects in large samples that cover entire diverse populations are still rare. We will analyze data from SHARELIFE, a retrospective survey conducted as part of the Survey on Health, Aging, and Retirement in Europe (SHARE) in 2009. This survey provides detailed data on events in childhood including those during the war as well as several measures of exposure to war shocks such as experience of dispossession, persecution, combat in local areas, and hunger periods for over 20,000 individuals in 13 European countries. We find that exposure to the war itself, and even more importantly to individual-level shocks caused by the war such as hunger periods, significantly predict old-age outcomes at older ages.

http://ftp.iza.org/dp6296.pdf

Infant Mortality Database

A very important resource for cross country research on early life conditions (and economic development in general) is the following infant mortality database. The authors deserve a huge amount of credit for compiling this important dataset.

Abouharb, M. Rodwan; Kimball, Anessa L.

A new dataset on infant mortality rates, 1816-2002

Source: JOURNAL OF PEACE RESEARCH 44 (6): 743-754

Abstract:

Systematic data on annual infant mortality rates are of use to a variety of social science research programs in demography, economics, sociology, and political science. Infant mortality rates may be used both as a proxy measure for economic development, in lieu of energy consumption or GDP-per-capita measures, and as an indicator of the extent to which governments provide for the economic and social welfare of their citizens. Until recently, data were available for only a limited number of countries based on regional or country-level studies and time periods for years after 1950. Here, the authors introduce a new dataset reporting annual infant mortality rates for all states in the world, based on the Correlates of War state system list between 1816 and 2002. They discuss past research programs using infant mortality rates in conflict studies and describe the dataset by exploring its geographic and temporal coverage. Next, they explain some of the limitations of the dataset as well as issues associated with the data themselves. Finally, they suggest some research areas that might benefit from the use of this dataset. This
new dataset is the most comprehensive source on infant mortality rates currently available to social science researchers.

http://www.anessakimball.com/docs/research/InfantMortalityRate_articlemanuscript.pdf

New IZA Working Paper: Family Background, Self-Confidence and Economic Outcomes

IZA DP No. 6117

Antonio Filippin, Marco Paccagnella:

Family Background, Self-Confidence and Economic Outcomes

Abstract:
In this paper we analyze the role played by self-confidence, modeled as beliefs about one's ability, in shaping task choices. We propose a model in which fully rational agents exploit all the available information to update their beliefs using Bayes' rule, eventually learning their true type. We show that when the learning process does not convergence quickly to the true ability level, even small differences in initial confidence can result in diverging patterns of human capital accumulation between otherwise identical individuals. As long as initial differences in the level of self-confidence are correlated with the socioeconomic background (as a large body of empirical evidence suggests), self-confidence turns out to be a channel through which education and earnings inequalities are transmitted across generations. Our theory suggests that cognitive tests should take place as early as possible, in order to avoid that systematic differences in self-confidence among equally talented people lead to the emergence of gaps in the accumulation of human capital.

http://ftp.iza.org/dp6117.pdf

Seminar on Maternal and Child Health with David Barker

For a summary of Barker's work see http://www.thebarkertheory.org/. Geary's Orla Doyle and Colm Harmon are also speaking at this event.

The First One Thousand Days: Policy Implications for Maternal and Child Health

The School of Public Health, Physiotherapy and Population Science is hosting a workshop on Thursday 1^st December 1pm-5pm, with a keynote lecture by Professor David Barker of the University of Southampton. Professor David Barker is a world-renowned authority on early life influences on later health and wellbeing and his developmental plasticity hypothesis has influenced a large body of research over the last two decades.

Please find attached flyer with details of the event.

Please RSVP to beth.kilkenny@ucd.ie by Friday 18^th November if you would like to attend.

www.ucd.ie/phps

www.ucd.ie/cshw

Birth Weight and Later Outcomes In Ireland

A report published in 2006 by the Institute for Public Health in Ireland established that there were substantial inequalities in birth weight. Finding that there is a social gradient in this outcome is hardly surprising, it is the norm in other countries, and indeed the norm for most if not all health related outcomes, those with higher incomes tend to fare better. The recent Growing Up in Ireland study provides the opportunity to examine this issue in further detail. The following graph reiterates the differences in birth weight by family background using both income and mother’s education as indicators of SES. The mean birth weight is substantially higher in the later income quintiles, while a year of extra education for mothers is associated, on average with an extra 13 grams. Of course this is a simple linear fit but it turns out that controlling for other factors reduces this slightly, but not by a whole lot. Of course it’s hard to be sure that this is a causal relationship and that maternal education really affects birth weight (and is not just correlated with some other factor which does), but this result is consistent with studies which adopt more experimental approaches such as “Mother's Education and the Intergenerational Transmission of Human Capital: Evidence from College Openings”, Currie and Moretti, Quarterly Journal of Economics (2003) 118 (4): 1495-1532, and the Geary Working Paper “Mother's education and birth weight”, Chevalier, A. and V. O'Sullivan (2007).

A question that arises is whether these disparities in birth weight should be a cause for concern, or rather how much concern. Apart from the higher costs and increased risk of mortality which are associated with infant health, a growing literature has linked birth weight to a number of different outcomes in later life. In other words these inequalities in infant health are likely to persist. I also pursue this with the GUI data, and find that birth weight is predictive of various indicators at age 9, and not just health. The following graph depicts the relationship between Drumcondra maths/reading scores and birth weight. Again, controlling for the rich set of information available in the data does not alter this relationship substantially. Omitted variable bias is still a concern of course, however these results are entirely consistent with the literature, and in this context there is good reason to believe that there is at least some causal component to these effects. For a good review on the health side see the recent paper Almond, D. and J. Currie (2011). "Killing Me Softly: The Fetal Origins Hypothesis." Forthcoming in the The Journal of Economic Perspectives. Numerous twin studies also support this view, for example Black, S. E., P. J. Devereux, et al. (2007) "From the cradle to the labor market? the effect of birth weight on adult outcomes" The Quarterly Journal of Economics 122(1): 409-439.

I will be releasing a working paper on this shortly.

The height of intelligence

The positive correlation between height and intelligence has been documented many times. It is attributed generally to deficits in early life nutrition. According to some this explains much of the height/earnings premium. So is there any evidence on this correlation for Ireland? Using the Growing Up in Ireland data I graph the students mathematics score against their height (adjusting for sex, SES and birthweight) along with a 95% confidence interval.
So yes there is a slight upward gradient but it flattens out above about 1.25 metres, possibly even dipping at the very top of the range, the raw correlation is .114. But on the whole it looks fairly flat and shorter people who want to be mathematicians should not be discouraged.

The height of depression?

A number of studies have suggested that a person's height is associated with depression with taller people being less likely to be depressed. This effect, if it exists, could be reactive whereby the individual experiences low self-esteem or perhaps bullying as a result of their low stature. Alternatively short stature could be a marker for poor early life conditions. The evidence seems unclear overall.
So what if anything can we tell from the Growing Up in Ireland data? Below I graph a depression index (for the main carer in the study) against their height, adjusting for age, household income and whether there is a partner in the house. This is not a random sample of the population remember: all of the respondents (i.e. the main carers) have a child in the study (most of whom are 8 years old) & almost all are female i.e. they are typically the mother.
While it may not be obvious there is indeed a slight gradient: taller people do have a lower depression score. The association is small: on average one additional centimetre in height is associated with a reduction in the depression score of .005 (half of one percent) of a standard deviation. So while it is statistically significant, arguably it is not significant otherwise.
To put things in context having a partner in the house has approximately one hundred times the effect of an additional cm in height (i.e. half a standard deviation), so hang onto your man, I guess.

Human Capital Development Before Age Five

New NBER working paper by Douglas Almond & Janet Currie

Abstract:

This chapter seeks to set out what Economists have learned about the effects of early childhood influences on later life outcomes, and about ameliorating the effects of negative influences. We begin with a brief overview of the theory which illustrates that evidence of a causal relationship between a shock in early childhood and a future outcome says little about whether the relationship in question biological or immutable. We then survey recent work which shows that events before five years old can have large long term impacts on adult outcomes. Child and family characteristics measured at school entry do as much to explain future outcomes as factors that labor economists have more traditionally focused on, such as years of education. Yet while children can be permanently damaged at this age, an important message is that the damage can often be remediated. We provide a brief overview of evidence regarding the effectiveness of different types of policies to provide remediation. We conclude with a list of some of (the many) outstanding questions for future research.

Nber Working Paper No. 15827

Some unpleasant anthropometric arithmetic

Patterns in- and correlates of- height is something that has featured in this blog regularly. Seeing this is the New Year I thought I would start with a good new story.
The graph below is a kernel regression of "malaise" a measure of low mood (due to Rutter I think) & height, measured at age 23. So great news if you are tall...
Patterns such as this have been noticed before (refs below) but knowing how to interpret it is trickier. Is it because of stigma or prejudice - remember the (in)famous Randy Newman song? Or is it a marker for bad early life conditions à la Barker perhaps? I don't know, off hand, how one might distinguish between these two hypotheses.

Martel L.F. & H.B. Biller (1987) Stature and Stigma Lexington: Lexington Press
Stack S. & I. Wasserman (1996) Height and risk of suicide Journal of Social Psychology

Douglas Almond on the effect of maternal fasting

nice VOX interview with Douglas Almond

link here

Early Life Conditions and the Black-White Achievement Gap

A recent NBER working paper (Birth Cohort and the Black-White Achievement Gap: The Roles of Access and Health Soon After Birth, by Chay, Guryan & Mazmuder) argues that convergence in black-white achievement test scores (including the military’s AFQT) observed in the US in the 1980s had its origins in the improvements in early life conditions of black infants in the 1960s. Almond Chay and Greenstone (2008) have previously argued that the removal of segregation in Southern hospitals was a major factor in these health improvements.

In this paper the authors use regional and temporal variation in post neonatal mortality rates, and conclude that “investments in health through increased access at very early ages have large, long-term effects on achievement, and that the integration of hospitals in the 1960s affected the test performance of black teenagers in the 1980s”.

Link

The Barker Hypothesis

Professor Jim Heckman recently gave lectures at the Irish Economics Association in Cork and UCD. Although the focus of these talks was on human capital formation, he also mentioned the importance of early life conditions for adult health. This aspect of the lasting impact of childhood circumstance is the focus of ongoing work in Geary.

David Barker, an epidemiologist from the university of Southampton, was the first to argue that many chronic diseases have their origins in infant health. I came across his website recently which provides an interesting outline of the Barker/Foetal Origins Hypothesis.

Recessions in the Long Run

The paper by Christopher Ruhm (Are Recessions Good For Your Health?) has been mentioned several times on this blog. However, this analysis deals with short run outcomes. Many of the researchers in Geary would argue that the effects of adverse shocks can only be evaluated over the course of a life span.

Two papers by van den Berg et al argue this point.

Economic Conditions Early in Life and Individual Mortality [AER, 2006]: van den Berg , Lindeboom & Portrait

Being born under adverse economic conditions leads to a higher cardiovascular mortality rate later in life – evidence based on individuals born at different stages of the business cycle: van den Berg, Doblhammer-Reiter & Christensen

In each case the authors find significant negative effects of being born into a recession. This raises concerns about focusing on the short run. It would be interesting to fast forward and examine the outcomes of the Irish babies born in 2007 v 2009, especially given the speed of the downturn in this country. Time machine anyone?