Association between birthweight and body mass index at 3 years of age

Background: Obesity in children is one of the risk factors for adulthood obesity, which then leads to the development of chronic diseases such as hypertension, hyperlipidemia and diabetes. In this study, we identified significant factors associating with the body mass index (BMI) at 3 years of age from the perinatal characteristics of children. Methods: A total of 588 children were included in the study. The BMI at 3 years of age was examined in conjuction with the possible variables such as parents' smoking status during pregnancy, parents' age at birth, gestational age, sibling number and live birth order. sex, birthweight, BMI at 1 month of age, weight gain during the first month of life and feeding method at 1 month of age. Results: Univariate analysis showed that birthweight (P < 0.0001), weight gain during the first month of life (P = 0.0012) and BMI at 1 month of age (P < 0.0001) were significantly associated with the BMI at 3 years of age. Of these factors, birthweight and weight gain during the first month of life were the independent factors correlating with the BMI at 3 years by multivariate analysis (P < 0.0001 and P = 0.0095, respectively). Conclusions: Infants with higher birthweight and/or greater weight gain during the first month of life may have a risk of being overweight at 3 years of age.