BACKGROUND: Growth patterns of exclusively and predominantly breast-fed infants differ from those of non-breast-fed infants, but less is known about associations among growth patterns and different durations of exclusive breast-feeding and the types and frequency of complementary foods. OBJECTIVE: We examined these associations, particularly between 4 and 6 mo of age, using data from a unique longitudinal 7-country study. DESIGN: Data from the World Health Organization Multinational Study of Breast-feeding and Lactational Amenorrhea on infants living in generally favorable environments were used. Multilevel analyses described growth and the relation between growth and variables related to feeding. RESULTS: Small differences in growth that were statistically significant but probably not biologically important were noted among infants in whom complementary foods were introduced at different times. Weight gain was more sensitive to feeding frequencies than were gains in length, but the cumulative 10-wk differences were small. The most extreme differences were equivalent to approximately 10 centiles of the weight and height distributions at 6 mo of age. CONCLUSIONS: These results do not provide compelling evidence of benefit or risk related to growth and the timing of introduction of complementary foods at any specific time between 4 and 6 mo of age. Thus, postnatal growth appears to not be sensitive to the differential timing of introduction of complementary foods nor to differential types and frequencies of complementary foods in healthy infants living in environments without major economic constraints and low rates of illness. These results, however, may not indicate growth differences in populations living in poor environments.
BACKGROUND: Growth patterns of exclusively and predominantly breast-fed infants differ from those of non-breast-fed infants, but less is known about associations among growth patterns and different durations of exclusive breast-feeding and the types and frequency of complementary foods. OBJECTIVE: We examined these associations, particularly between 4 and 6 mo of age, using data from a unique longitudinal 7-country study. DESIGN: Data from the World Health Organization Multinational Study of Breast-feeding and Lactational Amenorrhea on infants living in generally favorable environments were used. Multilevel analyses described growth and the relation between growth and variables related to feeding. RESULTS: Small differences in growth that were statistically significant but probably not biologically important were noted among infants in whom complementary foods were introduced at different times. Weight gain was more sensitive to feeding frequencies than were gains in length, but the cumulative 10-wk differences were small. The most extreme differences were equivalent to approximately 10 centiles of the weight and height distributions at 6 mo of age. CONCLUSIONS: These results do not provide compelling evidence of benefit or risk related to growth and the timing of introduction of complementary foods at any specific time between 4 and 6 mo of age. Thus, postnatal growth appears to not be sensitive to the differential timing of introduction of complementary foods nor to differential types and frequencies of complementary foods in healthy infants living in environments without major economic constraints and low rates of illness. These results, however, may not indicate growth differences in populations living in poor environments.