How common are big babies? About one in ten babies is born big in the United States (U.S.). Overall, 8.7% of all babies born at 39 weeks or later weigh between 8 lbs., 13 oz., and 9 lbs., 15 oz., and 1.7% are born weighing 9 lbs., 15 oz. or more (U.S. Vital Statistics). In the table below you can see the percentages listed separately for women who are not diabetic, those who have gestational diabetes, and those who have Type I or Type II diabetes.