For Malnourished Boys, Earliest Days a Critical Window for Cognitive Development

In rural Nicaragua where malnutrition is widespread, improved nutrition and health care during a boy’s first 1,000 days (from the beginning of his mother’s pregnancy to about age 2) has a lasting positive impact on cognitive development and learning, new research finds.

“The timing of the intervention was critical,” said Tania Barham of the University of Colorado-Boulder, who published the study with co-authors Karen Macours, Paris School of Economics and the National Institute for Agricultural Research (France), and John Maluccio, Middlebury College, in the latest issue of the American Economic Review.1

The researchers examined the results of a set of cognitive skills tests given at age 10 to about 400 boys whose households took part in a three-year program to improve diet and health. Boys whose households participated until their second birthday scored significantly higher than boys who received the program between ages 2 and 5. The tests measured skills related to learning, including information processing speed, receptive vocabulary, and memory.


Gestation and the first two years of life offer a crucial “window for cognitive skill formation” for boys, she said. The medical literature shows that from the time they are conceived, boys are at a greater risk of death or damage during early life than girls. The girls likely benefited from the better diet and health care as well, but the research team found no differences based on timing.


Better cognitive skills could have implications for the boys’ future earnings and lifelong well-being, according to the researchers. Other studies have linked low levels of cognitive skills to low school achievement, less schooling, and lower lifetime productivity and income; consequently, early deficits can translate into poor outcomes later and make breaking the cycle of poverty more challenging.2


Conditional Cash Transfers


The researchers evaluated a “conditional cash transfer” (CCT) program run in 42 rural Nicaraguan communities with poverty rates averaging above 80 percent. This social program offered mothers three years of regular cash payments on the condition they participated in health and nutrition education sessions, their children received regular preventive health care, and their elementary school-age children attended school. The payments represented a nearly 20 percent increase in household income.


The program was randomly phased in to allow researchers to measure its impact. Known as a “randomized controlled trial,” the approach is one of the most rigorous ways to evaluate the effectiveness of an intervention. The program was offered to half the communities in the first three years and the other half during the second three years; the differences between the two groups were evaluated five years after the program ended.


One of about 30 CCT programs worldwide, the Nicaraguan program aimed to increase spending on food, improve child nutrition, ensure basic health care, and boost school enrollment.3 Nicaraguan households that received the grants consumed significantly more fruits and vegetables, meat, and fats. Short-term evaluations showed “large and significant improvements in nutrition and health” among children in participating households; longer-term evaluations found evidence of increases in both school attainment and learning.4


Improved Physical Development


The researchers also found improved physical development as a result of the program. In the first years of the intervention, the boys whose households received the grants early were significantly taller than those participating later, but these differences narrowed after the later groups’ mothers began receiving the grants. By age 10 there were no height differences between the two groups, suggesting that in the area of physical development “interventions later in childhood can partly or even fully compensate for earlier deficits,” according to Maluccio.


“We know that early life circumstances shape adulthood—influencing health, education, and earnings,” he noted. Negative events in utero and early childhood—such as food shortages due to war or famines leading to low birth weight—are associated with poor outcomes later in life.


“But the evidence on the longer-run effects of positive interventions designed to improve health and nutrition is sparse and mixed,” he reported. These findings provide new support for nutrition and health programs that target the first 1,000 days.


Paola Scommegna is a senior writer/editor at the Population Reference Bureau.




    1. Tania Barham, Karen Macours, and John A. Maluccio, “Boys’ Cognitive Skill Formation and Physical Growth: Long-Term Experimental Evidence on Critical Ages for Early Childhood Interventions,” American Economic Review: Papers & Proceedings 103, no. 3 (2013): 467-71.


    1. Cesar Victora et al., “Maternal and Child Undernutrition: Consequences for Adult Health and Human Capital,” The Lancet 371, no. 9609 (2008): 340–57; and Douglas Almond and Janet Currie, “Human Capital Development Before Age Five,” in Handbook of Labor Economics 4B, ed. Orley Ashenfelter and David Card (Amsterdam: Elsevier Science, 2010).


    1. Ariel Fiszbein and Norbert Schady, Conditional Cash Transfers: Reducing Present and Future Poverty (Washington DC: The World Bank, 2009).


    1. Tania Barham, Karen Macours, and John A. Maluccio, “More Schooling and More Learning? Effects of a 3-Year Conditional Cash Transfer Program in Nicaragua after 10 Years” paper presented at the Population Association of America meetings, New Orleans, May 2013; summarized by the Massachusetts Institute of Technology, Jameel Poverty Action Lab.