Determine if Human Infant Weight Gain Can be Modulated to Prevent Obesity

This is a clinical intervention study to calibrate infant milk or formula intake and modulate infant weight gain to prevent the development of infant obesity. The studies will be performed at the Ana Abrão Breastfeeding Center, Federal University of São Paulo, Brazil. Postpartum women will be with pre-pregnant BMI 30 who are providing exclusive human milk via pumping and bottle (n = 50; 50 percent male and 50 percent female) will be recruited at the 7-9 week postpartum visit, Study women will be randomly assigned (computer generated; blocks of 10) to a Standard Feed (SF) or Calibrated Feed (CF) groups. Both groups will be seen at 2 week intervals for assessment of infant weight, supine length, BMI and skinfold thickness. Continuation of exclusive human milk will be confirmed with questionnaires. In the SF group, mothers will provide bottled human milk ad libitum. In the CF group, infant weight will be assessed in relation to the daily milk volume and approximate caloric intake (based upon maternal human milk sample analysis). Should infants be within 10th to 90th percentile of WHO BMI growth curves, no intervention will be made. Should the infant be greater than 90th percentile of WHO BMI, the provided human milk volume and daily calorie intake will be adjusted in relation to previously established normal volumes for newborn age, with the input of pediatric physician. In no case, will the daily milk volume or calorie intake be reduced by more than 10%. At the subsequent visit, adjustments in milk volume and calorie intake will continue, dependent upon the infant BMI trend, accommodating the normal increase in milk intake with advancing age. Should the infant be less than 10th percentile of WHO BMI, the maternal- infant dyad will be referred for a pediatric and nutrition consults to assess the cause and treatment for potential nutrient deficiency. At 26 wks, the investigators will assess the distribution of infant weight BMI between SF and CF groups. An identical Study will be undertaken (Standard Feed and Calibrated Feed), with the exception that only current formula feed mothers will be enrolled. All women will be provided a standard brand of commercial formula feed, for which total caloric content and composition will be determined. Data Analysis. The investigators will compare standard feed vs calibrated feed infant BMI curves with repeated measures ANOVA (time, BMI) with covariates of the group assignment. The investigators will compare infant weight and BMI curves by maternal BMI and infant birth weight, and between human milk and formula groups. The investigators will analyze growth curves of infants exceeding WHO standards which received adjustments in feedings to assess if early changes in growth curves or milk composition is predictive of weight changes, so as to determine the potential for interventions prior to 90th percentile.