Does lower birth order amplify the association between high socioeconomic status and central adiposity in young adult Filipino males?

Abstract

Objectives: To test the hypothesis that lower birth order amplifies the positive association between socioeconomic status and central adiposity in young adult males from a lower income, developing country context.

Design: The Cebu Longitudinal Health and Nutrition Survey is an ongoing community-based, observational study of a 1-year birth cohort (1983).

Subjects: 970 young adult males, mean age 21.5 years (2005).

Measurements: Central adiposity measured by waist circumference; birth order; perinatal maternal characteristics including height, arm fat area, age and smoking behavior; socioeconomic status at birth and in young adulthood.

Results: Lower birth order was associated with higher waist circumference and increased odds of high waist circumference, even after adjustment for socioeconomic status in young adulthood and maternal characteristics that could impact later offspring adiposity. Furthermore, the positive association between socioeconomic status and central adiposity was amplified in individuals characterized by lower birth order.

Conclusions: This research has failed to reject the mismatch hypothesis, which posits that maternal constraint of fetal growth acts to program developing physiology in a manner that increases susceptibility to the obesogenic effects of modern environments.

Figure 1

Theoretical model

Figure 2

Cubic relationship between birth order and model predicted birth weight (adjusted for maternal age, height, arm fat area, smoking and socioeconomic status).

Figure 3

The impact of young adult socioeconomic status on waist circumference is amplified for lower birth orders.

Figure 4

Mean body mass index growth curves (with 95% confidence intervals) for groups of males defined by firstborn status and socioeconomic status at birth.