Infant feeding and growth--a longitudinal study in three Swedish communities

In a prospective longitudinal study of 312 Swedish infants physical growth was analysed in relation to breast feeding, artificial feeding and some other possible determinants of growth. Weight and length at eight ages, from birth to 19.5 months as well as weight and length velocities for the corresponding intervals are reported. Almost all infants were breastfed during the first month of life and 50% were still breastfed at six months of age. The attained weights and lengths of these infants were generally above the national or international standards in early infancy and around the standard from six months of age. In a regression analysis the weight and length velocities are analysed in relation to feeding habits, birth weight, birth length and some other factors. Entirely breast-fed infants were shown to have a higher weight and length velocity than mixed- or formula-fed infants during the first three months of life. The artificially fed infants showed a catch-up in growth during the next three months and there was no difference in attained weight or length from six months of age due to previous feeding habits. The higher initial weight and length velocities of breast-fed infants were not caused by any catch-up due to unfavourable intra-uterine factors. Entirely breast-fed infants were heavier at birth; a difference which could be explained by differences in smoking habits during pregnancy. The consequences for the interpretation of individual growth patterns in early infancy and the need of an appropriate growth standard for the first six months of life are discussed.