BMI at birth and overweight at age four.

BACKGROUND

Extensive investigation has established that an elevated weight at birth is associated with subsequent obesity and obesity related negative health outcomes. The significance of overweight at birth, however, remains ill-defined. Historically, it has been difficult to approximate adiposity in infancy in a way that is both simple and meaningful. Body-mass-index (BMI) growth charts for children younger than two years of age only became available in 2006 when published by the WHO.

METHODS

This retrospective cohort analysis utilised anthropometric data extracted from the electronic medical record of a large integrated healthcare system in North Carolina. BMI and weight-for-age (WFA) >85% of WHO growth charts measured newborn overweight and macrosomia respectively. Logistic regression models assessed the associations between newborn macrosomia and overweight and overweight at 4 years of age, as well as associations with maternal BMI. Models included demographic data, gestational age, and maternal diabetes status as covariates.

RESULTS

Both BMI and WFA >85% at birth were significantly associated with overweight at age 4 years. However, the greater odds of overweight was associated with newborn BMI >85%, with an adjusted odds ratio (AOR) of 2.08 (95% confidence interval [CI]: 1.4-3.08) versus 1.57 (95% CI: 1.08-2.27). Maternal obesity was also more robustly correlated with newborn BMI >85%, AOR of 4.14 (95% CI: 1.6-10.7), than with newborn WFA >85%, AOR of 3.09 (95% CI: 1.41-6.77).

CONCLUSIONS

BMI >85% at birth is independently associated with overweight at 4 years. Newborn overweight is perhaps superior to newborn macrosomia in predicting overweight at age 4.