Born Last: How Birth Order Affects Childhood Outcomes

Economic theory holds up competition as an ideal way for society to allocate limited resources. Although competition is often discussed in terms of equilibrium supply and demand in a given market, the strategic allocation of resources also has significant consequences within individual households. For example, in large families where there is not enough food to go around, the decisions families ultimately make have an impact on the health of each family member.

In order to better understand resource allocation within large families, researchers Embry M. Howell, Nikhil Holla, and Timothy Waidmann studied birth order as a risk factor for poor health in a recent paper released by the Urban Institute’s Health Policy Center. While other studies have examined the relationship between birth order and health outcomes, Howell et al.’s study constitutes an important contribution to the field because it specifically focuses on a representative group of African countries where lifetime fertility and childhood mortality rates are persistently high. To understand the relationship between birth order and health in these countries, the researchers measured the differences in nutrition and mortality among siblings depending on the order in which they were born.

On average, Howell et al. found that for each successive birth order position (e.g. the fourth born as opposed to the third born child), children ages one to four face a 13 percent increase in mortality risk, while children ages five to fourteen experience a 10 percent increase.

This study examined 18 developing African countries that were surveyed at least once per decade since 1985 as part of the Demographic and Health Surveys Program. The 18 countries selected by the authors are reasonably representative of Africa as a whole and include about half of the continent’s total population. In particular, the selected countries exhibit a wide range of mortality rates for children under the age of five, from 2.4 percent in Egypt to 11.5 percent in Mali. Furthermore, although under-five mortality is declining across Africa, the rate of decline varies from 0.3 percent in Zimbabwe to 5.2 percent in Rwanda. Within these 18 countries, the authors investigated competition for resources within each household as families became larger.

The researchers measured nutrition as a function of whether a child experiences stunted growth or low weight, has consumed fewer than four food groups within the past day and/or has consumed fruits or vegetables within the past day. Since infant nutrition depends primarily on breastfeeding, and because many indicators of an infant’s health are closely linked to the mother’s health, the researchers excluded children under the age of one from the study. On average, the researchers found that, for children affected by food scarcity within their family, children ages one to four are more likely to experience stunted growth or low weight, while children ages five to fourteen are more likely to consume fewer food groups, particularly fewer fruits and vegetables.

Like most research, this study does involve potential biases. For example, some of the nutrition information was gathered by asking mothers to describe their children’s food intake over the course of the past day. Although it is likely that the only source of food is within the household—especially for very young children, it is nevertheless plausible that a mother of several children may not precisely track the different foods and amount of food each child eats.

The study as a whole, however, makes a strong case for the necessity of family planning in any strategy seeking to alleviate the burden of extreme poverty in Africa. Whether birth order affects childhood mortality directly through the mechanism of malnutrition, or through its relationship with other cultural and economic factors, it is evident that until families can ensure that their children simply survive into adulthood, concerns like education and employment are trivial. As a result, policymakers should use the evidence of this association between birth order and childhood mortality to inform reproductive health measures to guarantee that healthy childhood development is a priority.

Article source: Howell, Embry M., Holla, Nikhil, Waidmann, Timothy A. “Being the Younger Child in a Large African Family.” Urban Institute (2016).

Featured photo: cc/(borgogniels, photo ID: 490399330, from iStock by Getty Images)