Race/Ethnic Differences in Birth Size, Infant Growth, and Body Mass Index at Age Five Years in Children in Hawaii

Background: Factors at birth and infancy may increase risk of being overweight in childhood. The aim of this study was to examine the relationship of birth size and infant growth (2-24 months) with BMI at age 5 years in a multiethnic population. Methods: This was a retrospective study (using electronic medical records of a health maintenance organization in Hawaii) of singleton children born in 2004-2005, with linked maternal and birth information, infant weights (n=597) and lengths (n=473) in the first 2 years, and BMI measures at age 5 years (n=894). Multiple regression models were used to estimate the association of BMI at age 5 years with birth size and infant growth. Results: Birth weight was positively associated with BMI at age 5 years, adjusting for gestational age, sex, race/ethnicity, and maternal prepregnancy weight, age, education, and smoking. A greater change in infant weight was associated with a higher BMI at age 5 years, though the effect of birth weight on BMI was neither mediated nor modified by infant growth rate. Birth weight, change in infant weight, and BMI at age 5 years varied by race/ethnicity. Change in infant BMI in the first 2 years was higher in other Pacific Islanders and whites (=0.966; confidence interval [CI]=0.249-1.684; p=0.02) than in Asian, other, and part Native Hawaiian race/ethnic groups. Conclusions: Early biological measures of birth weight and infant weight gain varied by race/ethnicity and positively predicted BMI at age 5 years.