Brief reportEarlier appearance of the ossification center of the femoral head in breast-fed versus formula-fed infants

ObjectiveThe aim of this study was to evaluate possible differences in the rate of appearance of the femoral head ossification center (FHOC) in infants according to the type of feeding (exclusive breast-feeding, formula, mixed feeding).MethodsA retrospective study was conducted in a population of 285 healthy infants who consecutively underwent echographic evaluation of the hip as a screening for hip dysplasia from April 1 through October 31, 2008. For each infant, type of feeding, sex, gestational age, weight at birth, and age at the time of echographic examination were recorded. Data analysis was performed in the entire sample population and in a subpopulation of 143 infants after exclusion of preterm or low-birth-weight infants and those who underwent echographic examination outside the scheduled age range. Data were analyzed by chi-square test, Kruskal-Wallis test, and multiple logistic regression analysis.ResultsAn FHOC was present in 48.3% of breast-fed infants, 25.7% of formula-fed infants, and 28% of the mixed feeding group (P = 0.001). In multiple logistic regression analysis, the best regression model included the following variables: age at test (P = 2.23 × 10−7), gestational age (P = 0.0017), and exclusive breast-feeding (P = 0.0003). Similar results were obtained in the selected subpopulation of 143 infants (FHOC in 54.2% of breast-fed group, 28.2% of formula-fed group, and 33.3% of mixed-feeding group, P = 0.01).ConclusionExclusive breast-feeding may be associated to an earlier appearance of FHOC in a population of normal infants compared with formula feeding.