Growth of Japanese breastfed infants compared to national references and World Health Organization growth standards.

Objective: The aim of this study was to compare the growth of Japanese infants that were exclusively breastfed to those of national references and World Health Organization (WHO) standards.

Methods: Mothers, who delivered a normal term baby and had been exclusively breastfeeding for at least 4 months, were enrolled. The lengths, body weights and head circumferences of 647 children, aged 0-24 months, were obtained and compared to national references and WHO standards.

Results: Comparisons of the national references for both length and body weight indicated that breastfed infants were significantly shorter and lighter almost throughout the first 24 months. Conversely, head circumferences of breastfed infants were significantly larger at 1 and 6 months of age in boys and 6 months in girls. Compared to WHO standards, similar trends to the comparisons with national references were found.

Conclusions: There were significant differences identified between the growth of breastfed infants and existing national references and WHO standards.