Background: Growth reference charts should be periodically adapted to the population in which they will be applied, according to ethnic variation, secular growth change, and current feeding patterns.
Objective: To perform an anthropometric analysis of healthy contemporary infants aged 0-24 months and to compare the results with the most commonly used reference values.
Patients and methods: We performed an observational, longitudinal and retrospective study of weight and length measured in the routine health checks of all infants born between 1998 and 2001 in the same Health Area and who received the infant formula beikost at a similar age. Exclusion criteria were low-birth-weight (< 2,500 g), prematurity, and chronic disease. Infants who did not complete the follow-up until the age of 2 years were also excluded. We calculated the means for each age, sex and variable. The Z-score represented by these means in the longitudinal charts most commonly used in Spain (Fundación Orbegozo) and in the Euro-Growth study were calculated and were compared with Student's one-sample t-test.
Results: Of the 256 infants born in the study period, 30 were excluded (11.71%) and 226 infants were finally enrolled (52.2% boys). In relation to the Spanish reference values, in boys the weight Z-score at 12 and 24 months was +0.28 (95% CI: +0.10/+0.45) and +0.33 (95% CI: +0.15/+0.52) respectively, and the length Z-score was +0.59 (95% CI: +0.43/+0.76) and +0.52 (95% CI: +0.33/+0.72). In girls the weight z-score was similar to that for boys (+0.24 [95% CI: +0.08/+0.40] and +0.37 [95% CI: +0.17/+0.57]) but growth in length was greater (+0.86 [95%CI: +0.66/+1.06] and +0.73 [95% CI: +0.52/+0.94]). This difference was statistically significant in all cases. At the age of 2 years, 17.75 % of girls and 8.47 % of boys were above the 97th percentile in length. No differences in length at 2 years were found in either boys or girls in relation to the Euro-Growth study.
Conclusions: Anthropometric measurements in the first 2 years of life showed a significant increase in relation to the charts designed 20 years ago, especially in length and in girls.