Growth patterns and iron status of infants who were breast-fed throughout their first year of life were examined in four populations: 1) a group of high socioeconomic status in California (the DARLING Study), 2) infants of normal birth weight (NBW) but from low-income families in Honduras, 3) low-birth-weight (LEW), full-term infants in Honduras, and 4) infants in Ghana. z Scores were calculated by using both the current National Center for Health Statistics reference data and a pooled data set based on breast-fed infants in six industrialized countries. The NEW infants in Honduras showed rapid growth in the first few months and were similar in weight-for-age to the DARLING infants until approximate to 9 mo. By contrast, the LEW infants remained far below the other cohorts throughout the first 12 mo, despite an initial period of catch-up growth. In the Ghanaian infants, weight-for-age faltered beginning at 3-4 mo, but length-for-age did not falter until after 9 mo. Weight-for-length was highest in the NBW Honduran infants and lowest in the Ghanaian infants. When z scores were adjusted for birth weight and maternal height, no significant faltering was evident in either weight or length in any of the cohorts during the first 12 mo. Thus, when breast-feeding is continued during the first year of life and efforts are made to ensure adequate complementary feeding after 6 mo, if growth faltering occurs it is probably attributable to prenatal factors and maternal stature. Population differences in iron status reflected variation in birth weight and in the use of iron-rich foods. Therefore, efforts to prevent child stunting and malnutrition must pay attention to prenatal as well as postnatal factors.
