Body weight at developmental age in siblings born to mothers before and after surgically induced weight loss.

BACKGROUND: To gain insight into the role of epigenetic factors in determining body weight in adolescence, we studied the body weight of siblings born to the same mother before and after biliopancreatic diversion (BPD) for obesity. The study was performed in a university hospital during a 20-year period. METHODS: The siblings born before and after BPD were retrospectively rated by their mother as normal, overweight, or obese at 1, 6, and 12 years. RESULTS: At 1 and 6 years, the body weight was rated as similar in the subsets. However, at 12 years of age, a greater percentage of those born before BPD were considered overweight (42% versus 33%) and obese (22% versus 3%; P <.009) than their counterparts born after BPD. Considering only the subjects aged 21-25 years at the study period, the body weight and body mass index in subjects born before BPD were greater (P <.02 and P <.012, respectively) than in those born after BPD (79.5 ± 16.5 kg versus 66.7 ± 11.8 kg, and 27.5 ± 3.9 kg/m(2) versus 23.4 ± 3.7 kg/m(2), respectively). CONCLUSION: The results of the present study, in which the influences of the genetic pattern and environmental and educational factors were minimized, show that adolescents born to post-BPD mothers weigh less than their siblings born to the same mother before BPD when she was still obese. An insulin-resistant milieu during pregnancy could account for the greater body weight later in adolescence.