Lower energy expenditures in infants from obese biological mothers

Background: Previous studies in adults have found that a lower resting metabolic rate is a predictor of future body weight gain. Methods: To determine if energy expenditures are reduced in infants born to obese mothers, 21 healthy infants (3.9 +/- 1.9 months) born to lean (n = 7, BMI < 25 kg/m(2)), overweight (n = 7, BMI between 25-30) and obese (n = 7, BMI> 30) mothers, respectively, participated in this study. Measurements of infant weight, length and skin-fold thicknesses, and mother's weight and height were obtained. Infant energy expenditure was measured for 4-hours using the Enhanced Metabolic Testing Activity Chamber. Metabolic data were extrapolated to 24-hours and adjusted for differences in age and body composition using linear regression analysis (SPSS, version 13) and expressed as kcal/day. Differences between the three groups were determined by one way ANOVA with the Bonferroni Post Hoc test procedure (p < 0.05). Results: Infants born to obese mothers had a greater BMI (16.7 +/- 1.2) than those from both the overweight (15.3 +/- 1.4, p < 0.05) and lean groups (15.1 +/- 1.3; p < 0.05). The infants of obese mothers had greater body fat (26.8 +/- 2.1) than those from the overweight group (22.4 +/- 5.0, p < 0.06). Infant BMI correlated (r = 0.53; p < 0.01) with that of their mothers. Extrapolated 24-h EE (kcal/d) correlated with fat-free mass (r = 0.94; p < 0.01). Infants extrapolated 24-h EE from both obese (472.1 +/- 30.7 kcal/d; p < 0.05) and overweight groups (471.8 +/- 39.5; p < 0.05) were lower than those of the lean group (532.4 +/- 30.7). Conclusion: Lower extrapolated 24-h energy expenditure was present in infants of overweight and obese biological mothers during the first three to six months of life. Furthermore, these infants showed increased BMI and body fat. If these changes are unchecked future childhood obesity may result.