Objective To determine whether high weight for length at the 18-month well-baby visit is predictive of overweight or
obese body mass index (BMI) at the 4- to 6-year well-child visit.
Design Retrospective cohort study using objective electronic medical record measurements.
Setting Eighteen family practices forming a community family health organization in Peterborough, Ont.
Participants All children from the family health organization practices with at least 1 set of weight and length or
height measurements at age 17 to 19 months and age 4 to 6 years (N = 126).
Main outcome measure Relative risk (RR) of overweight BMI and RR of obese BMI at 4 to 6 years of age for normal
versus overweight or obese 18-month-olds.
Results Children who were either overweight or obese at their 18-month visits (n = 37) were more than twice as
likely to be obese at age 4 to 6 years than children who had healthy weights at 18 months were (n = 89; RR = 2.71, 95%
CI 1.13 to 6.47). The subgroup of obese 18-month-olds (n = 13) were at more than 3 times the risk of being obese at
age 4 to 6 years than their healthy-weight-for-length counterparts (RR = 3.42, 95% CI 1.20 to 9.78). Thirty-one percent
of obese 18-month-olds were obese at 4 to 6 years and a further 31% were overweight.
Conclusion High weight for length at 18 months substantially increased a child’s risk of being overweight or obese
at 4 to 6 years of age. Most overweight and obese 18-month-olds in this study did not achieve healthy BMIs by 4 to 6
years of age. A brief glance at the 18-month weight-for-length chart can easily help identify these high-risk toddlers.