By Lisa Rapaport (Reuters Health) – Roughly half of first-time mothers in the U.S. gain too much weight during pregnancy, about the same proportion who are overweight at the start, a study finds. Researchers compared data on more than 2 million U.S. women to a group of about 1,650 of their peers in Germany, where almost three-fourths of first-time mothers started pregnancy at a healthy weight and only 27 percent exceeded weight gain recommendations. “The differences in overweight rates pre-pregnancy and in weight gain are surprising,” lead study author Dr. Joachim Dudenhausen, an obstetrics researcher at Charite University Medicine in Berlin, said by email.