Effects of feeding patterns during the first 6 months on weight development of infants ages 0-12 months: a longitudinal study.

The purpose of this study was to investigate the effect of feeding patterns during the first 6 months on weight development of infants ages 0-12 months. Using monitoring data from the Maternal and Child Health Project conducted by the National Center for Women and Children's Health of the Chinese Center for Disease Control and Prevention from September 2015 to June 2019, we categorized feeding patterns during the first 6 months as exclusive breastfeeding, formula feeding, or mixed feeding. We calculated weight-for-age Z scores (WAZ) according to the World Health Organization's (WHO) 2006 Child Growth Standard using WHO Anthro version 3.2.2. A multilevel model was used to analyze the effect of feeding patterns during the first 6 months on the WAZ of infants ages 0-12 months in monitoring regions. Length of follow-up (age of infants) was assigned to level 1, and infants was assigned to level 2. Characteristics of infants, mothers, and families and region of the country were adjusted for in the model. The average weight of infants ages 0-12 months in our study (except the birth weights of boys who were formula fed or mixed fed) was greater than the WHO growth standard. After we adjusted for confounding factors, the multilevel model showed that the WAZ of exclusively breastfed and mixed-fed infants were statistically significantly higher than those of formula-fed infants (coefficients = 0.329 and 0.159, respectively; P < 0.05), and there was a negative interaction between feeding patterns and age (both coefficients = - 0.020; P < 0.05). Infants who were exclusively breastfed were heavier than formula-fed infants from birth until 12 months of age. Mixed-fed infants were heavier than formula-fed infants before 8 months, after which the latter overtook the former. Infants' weight development may be influenced by feeding patterns during the first 6 months. Exclusive breastfeeding during the first 6 months may be beneficial for weight development of infants in infancy.