Growth of breast-fed infants deviates from current reference data: A pooled analysis of US, Canadian, and European data sets

Objective. To compare growth patterns of a large sample of breast-fed infants with the current World Health Organization (WHO)/Centers for Disease Control and Prevention (CDC) reference data. Methods. Data from seven longitudinal studies of infant growth in North America and northern Europe were pooled (n = 453 breast-fed infants). Weight, length and head circumference were compared with the WHO/CDC reference, and repeated-measures analysis of variance was used to examine associations between growth patterns and breast-feeding duration, age of introduction of solid foods, and use of other milks. Results. In comparison with WHO/CDC reference data, infants breast-fed for at least 12 months (n = 226) grew more rapidly in the first 2 months and less rapidly (particularly in weight) from 3 to 12 months; the mean z score at 12 months was -0.53 for weight for age, -0.29 for length for age, and -0.32 for weight for length. In contrast, mean head circumference was well above the WHO/CDC median throughout the first year of life. These patterns were generally consistent across studies. In the full sample (n = 453), a longer duration of breast-feeding was associated with a greater decline in weight for age and weight for length but not length for age. Conclusion. These results suggest that if growth charts are to reflect patterns consistent with those of infants following WHO feeding recommendations, new reference data based on breast-fed infants are needed.