LAUSR

Growth of infants fed isocaloric infant formulas differing in nutritional content was studied. Twenty-three of 109 randomized clinical trials reported some difference in weight, length or head circumference between formula groups. Logistic regression demonstrated no relationship between finding a significant difference in a growth outcome with enrollment prior to 15 d or observation of 15 wk, parameters specified in regulation. Sample size and year of publication also were not correlated with report of a significant growth difference, though reporting separate data by sex was (p = 0.012). The difference in mean weight gain between control and test formula groups was comparable to that between formula-fed and breast-fed infants (1 g/d) and smaller than that between male and female infants (4 g/d). Encouraging alternate study designs with flexible enrollment ages and infants who transition from breastfeeding to formula would gain information on physiologic outcomes and common feeding behaviors, as well as growth.