Relationship between feeding modes and infant weight gain in the first month of life.

Breast-feeding and human milk are beneficial for both mothers and their children. This retrospective study aimed to clarify whether differences in feeding mode influence infant weight gain in the first month of life. We analyzed the pregnancy charts of 422 women who delivered at a birthing center in rural Japan between August 1998 and September 2007. The inclusion criteria were low-risk, full-term pregnancy (duration, 37-42 weeks), spontaneous vaginal delivery, and a healthy infant (1 min Apgar score of ≥8) who underwent a health check-up at 1 month postpartum. The subjects were classified into three groups on the basis of feeding modes: exclusive breast-feeding group (28.9%), mixed-feeding group (55.9%) and exclusive formula-feeding group (15.2%). The weight gain/day was 39.7±9.3 g (range, 18.5-67.4 g), 39.5±9.4 g (range, 13.8-64.5 g) and 39.0±9.5 g (range, 14.4-65.3 g) in the exclusive breast-feeding, mixed-feeding and exclusive formula-feeding groups, respectively. Apart from the rate of maternal smoking, which was lower in the exclusive breast-feeding group, no other significant differences were observed among the three groups. This study revealed that there were no differences in weight gain among infants raised exclusively on breast milk and those raised exclusively on formula milk.