Objectives: To investigate the combined effects of size at birth and maternal education on prevalence of overweight and obesity among 18-year-old men.
Methods: We studied the associations of weight for gestational age and maternal education with body mass index (BMI), overweight and obesity by multivariate linear and logistic regression, adjusted for mother's age, parity and diabetes in a register-based cohort of 6535 men born between 1973 and 1985. Further adjustments for mother's height, pre-pregnancy weight, weight gain and smoking during pregnancy were made in a subsample of 1103 men born between 1982 and 1985.
Results: Mean BMI and prevalence of overweight and obesity decreased with higher maternal education. Mother's BMI and smoking were the strongest predictors of sons' overweight and obesity and essentially accounted for the variation in son's overweight by maternal education. The association of size at birth with later overweight was present only in sons born to mothers who were nonsmokers (odds ratio per 1 standard deviation weight for gestational age z-score 1.46, 95% CI 1.18-1.81) and became substantially reduced on adjustment for mother's pre-pregnancy BMI. Length of gestation was not statistically significantly associated with BMI at age 18.
Conclusions: Maternal overweight and maternal smoking were the strongest determinants of offspring overweight and its social patterning, and should be a priority for public health policies.