The most incisive guide to issues facing the American family today . . . An invaluable resource for anyone wishing to stay on the cutting edge of research on family trends.

-W. Bradford Wilcox
Associate Professor of Sociology, University of Virginia 

Only Child, Overweight Child

Bryce J. Christensen and Nicole M. King

A flood of research implicates the decay of family life as a prime reason that so many children are now overweight. Swelling that flood is a study recently completed by a team of epidemiologists in Sweden, Belgium, Spain, Denmark, Germany, Hungary, Italy, Sweden, Estonia, and Cyprus. Complementing other studies identifying the single-parent household as a prime setting for problems of childhood weight control, this new international study identifies the child without siblings—a creature of the Birth-Dearth generation—as a child particularly likely to experience such problems.

To isolate the statistical correlates of children’s being overweight, the researchers pored over cross-sectional data collected for 12,720 children ages two to nine living in eight European countries (all of the countries—except Denmark—with scholars represented on the research team). These data clearly establish that the only child is decidedly at risk of becoming overweight. Using a sophisticated statistical model that took into account such factors as parental education, parental weight, and gender, the researchers established that the single children in their survey were over half-again more likely than peers with siblings to be overweight (Odds Ratio of 1.52). What is more, this elevation of the only child’s risk of becoming overweight was especially pronounced among the older age group, ages six through nine (Odds Ratio of 1.70).

In interpreting their findings, the researchers acknowledge that, compared to peers with siblings, “fewer only children had two-parent households; they had less play time outdoors; a higher propensity to consume sugar; and were more likely to have parents supportive of food as a reward and television in the bedroom.”

Still, the researchers insist that “the excess risk of overweight among children without siblings” is so “robustly observed” that it persists even in statistical analyses that take into account the “behavioral mediating factors” such as “playtime, screen time per day, [and] dietary propensities for sugar or fat.”

At a time when approximately 22 million European children (not to mention millions of American children) are overweight, the researchers recognize the international importance of studies such as theirs. Remarkably few babies have been born in the industrialized West in recent decades. But an alarming number of those babies are growing up surrounded not by healthy siblings but instead by their own all-too-corpulent flesh.

(M. Hunsberger, “Overweight in Singletons Compared to Children with Siblings,” Nutrition & Diabetes 2.7 [2012]: e35.)