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TABLE B.1 Studies of the Effects of Malnutrition on Educational Outcomes SourceCountryDataChildrenIndicatorImpact on Education School grade attainment Grantham-McGregor BrazilLongitudinal, 2,041malesHAZ < –2; HAZ –2 to–1versus > –10.91lower grade and others20071982–2001attainment; 0.44lo grade attainmenta Maluccio, Hoddinott, Guatemala (rural)Longitudinal, 1,469Nutrition supplement1.0higher grade and Behrman 20061969–2004attainment (women Daniels and Adair Philippines (Cebu)Longitudinal, 1,970HAZ < –3; HAZ –3to–2; HAZ –20.80lower grade at 20041983–20020.33lower grade at 0.12to–1versus > lower grade attainment Alderman and othersUganda (rural) Longitudinal,570HAZ 0.68lower grade at 20061983–2000per 1 HAZ decline Learning productivity (grade equivalents) Behrman and othersGuatemala (rural)Longitudinal, 1,448HAZ0.84school year equiv 20061969–2004per 1HAZ Glewwe, Jacoby, andPhilippines (Cebu) Longitudinal, 1,016HAZ; HAZ < –2.50.8school year equiv King 20011983–95per 1 HAZ; 1.8school y equivalent per 1HAZ School dropout and grade repetition Maluccio, Hoddinott, Guatemala (rural)Longitudinal, 1,469Nutrition supplement0.1grade per year f and Behrman 20061969–2004school progression ( Walker and othersJamaica (Kingston)Longitudinal, 167HAZ < –2versus HAZ > –1100%higher school dr 20051986–2003rate by age17–18 142
Daniels and Adair Philippines (Cebu) Longitudinal, 1,970HAZ < –3; HAZ –3to–2; HAZ –2to–118%grade repetition; 20041983–2002grade repetition; 5% repetitionb Primary school enrollment Glewwe and Jacoby GhanaCross-sectional 1,757HAZ0.34year delayed s 19951988–89enrollment per 1-unit decrease in HAZ Alderman and othersPakistan (rural)Longitudinal, 5340.5HAZ increase18%increase in girls 20011986–91enrollment; 4%incre boys’ enrollment Glewwe, Jacoby, and Philippines (Cebu) Longitudinal 1,016HAZ2months delayeden King 20011983–95per 1-unit HAZ decline Alderman and othersUganda (rural)Longitudinal, 570HAZ 0.4year delayed enr 20061983–2000per 1-unit HAZ decline Effect of diarrhea Lorntz and othersBrazil Longitudinal 77Number of diarrheal episodes0.7month delayed s 2006(shantytown)1993–2001(0–2years)enrollment per episode of diarrhea Source: Compiled by World Bank team. a. Estimated here from table 5in Grantham-McGregor and others (2007). b. Repetition rates are relative to less than –1standard deviation; estimated here from odds ratios and data presented in Daniels and Adair (2004).
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estimate that mild stunting (HAZ –1 to –2) is associated with a loss of 0.4 years of schooling.
Alderman and others (2001), using longitudinal data relating to 560 chil- dren in rural Zimbabwe, find that a decline in HAZ of 1 is associated with a loss of 0.68 years of grade attainment and 0.4 years of delayed primary school enrollment. Grade attainmentis defined as completed grades in primary and secondary school.
Behrman and others (2006), using longitudinal data of 1,448 children followed into adulthood in rural Guatemala, assess the effect of preschool, schooling, and postschooling experiences on adult cognitive skills (reading comprehension and nonverbal skills). They find that preschool nonstunting (HAZ ≥–2) increases reading comprehension test scores by the same amount as 4.2 additional years of schooling attainment. Using sample and subsample mean values of HAZ reported in the study, an improvement in HAZ of 1 has an effect on reading comprehen- sion equivalent to nearly one additional year of schooling attainment. Stunting is also found to have a profound negative effect on nonverbal test scores. To the extent that nonverbal cognitive skills may affect learning productivity per year of schooling, this estimated effect of a change in HAZ of 1 on schooling attainment is conservative.
Maluccio, Hoddinott, and Behrman (2006) use the same data set to evaluate the effect of early childhood nutrition supplementation in Guatemala. The supple- ment was found to decrease the prevalence of severe stunting by 50 percent, increase the height of three-year-old children by 2.5 centimeters, and increase school grade attainment by one full year for women. No significant effect on schooling was found for men. The effect for women comes through a reduction in women who never attended school and an increase in women who progressed into secondary school. Women who received supplementation progressed faster through school than women who did not receive supplementation, at a rate of 0.1 grade per year in school.
Walker and others (2005), using longitudinal data of 167 children in Kingston, Jamaica, find that 17- to 18-year-olds, stunted by the age of two (HAZ < –2), had a school dropout rate twice as high as children who were not stunted (HAZ > –1).
Daniels and Adair (2004) use longitudinal data of 1,970 children in the Cebu metropolitan area (urban and rural households) in the Philippines. They estimate odds ratios for completing high school, delayed enrollment, and grade repetition in relation to early childhood stunting. Using the odds ratios and data presented in their article, one can infer that severe stunting in early childhood (HAZ < –3) is associated with 0.80 years of lower grade attainment, that moderate stunting (HAZ –2 to –3) is associated with 0.33 years of lower attainment, and that mild stunting (HAZ –1 to –2) is associated with 0.12 years of lower attainment. Daniels and Adair (2004) also find that severe stunting is associated with repeating a grade
at least once (18 percent of severely stunted children) and that 5 percent of mildly stunted children repeat a grade at least once as a result of stunting.
Glewwe, Jacoby, and King (2001), using longitudinal data relating to more than 1,000 children in the Cebu metropolitan area, investigate the effect of stunting on learning productivity per year of schooling through primary school using achievement test scores (sum of math and English). They then convert the effect of stunting on test scores into the extra months of schooling it takes to compen- sate for the difference in test scores. They find that the effect on test scores of a change in HAZ of 1 is equivalent to 0.8 year of school attendance, and for the more severely stunted children (HAZ < –2.5), it is equivalent to 1.8 years of schooling. Glewwe, Jacoby, and King (2001) also find that a decline in HAZ of 1 delays primary school enrollment by two months and increases the probability of first-grade repetition by 9 percent. Using the baseline data in Daniels and Adair (2004) on frequency of grade repetition by stunting status, they find that a grade repetition of 9 percent is equivalent to a 0.5-month delay in labor force entry for a severely stunted child and a 0.4-month delay for a mildly stunted child.
Alderman and others (2001), using longitudinal data on more than 500 chil- dren in rural Pakistan, find that a 0.5 increase in HAZ is associated with an 18 percent increase in girls’ school enrollment and a 4 percent increase in boys’
school enrollment.
Glewwe and Jacoby (1995) find in a study of children in Ghana, albeit using cross-sectional data, that a decline in HAZ of 1 is associated with a 0.34-month delay in primary school enrollment.
Diarrhea and Education
Lorntz and others (2006), using longitudinal data on children in a shantytown in northern Brazil, estimate the effect of early childhood diarrheal episodes on subse- quent timing of primary school enrollment. They find a 0.7-month delay in enrollment per diarrheal episode in the first two years of life. The median number of episodes in the first two years of life was 4.5 per year. On average, this finding corresponds to a two-week prevalence rate of nearly 22 percent, which is the same as reported in the 2003 Ghana Demographic and Health Survey for children under two years of age. Reducing this prevalence rate by half (that is, to 11 percent) would suggest a reduction in delayed enrollment by about three months.
Conclusions
The literature reviewed and presented in table B.1 provides substantial evidence of a significant effect of malnutrition on children’s educational performance. The single most important effect is reduced learning productivity during schooling, followed by reduced grade attainment. Delayed primary school enrollment and
grade repetition, while important in their own rights, have a much lesser conse- quence for lifetime income (see appendix D and chapter 5).
The effects of malnutrition on educational performance, as applied to Ghana and Pakistan to estimate the impact on lifetime income, are presented in table 5.6 (see also table D.7 in appendix D). The attributable fraction of malnutrition (stunting) from diarrheal infections associated with water, sanitation, and hygiene is discussed in appendixes A and D. The relation between educational perform- ance and future income is discussed in chapter 5.
Note
1 This appendix is based on a review of several recent longitudinal studies that looked at the effect of low height for age in childhood on educational outcomes. This review was carried out by Bjørn Larsen (consultant) specifically for this report.
THE ESTIMATES IN TABLE C.1 ARE FROMthe new study by the World Health Organization (Fewtrell and others 2007). The study incorporates the effects (through malnutrition) of water, sanitation, and hygiene on mortality and disease burden.