Gaining too much weight during pregnancy may lead to a larger birth weight, a new study has found. Researchers say women who gain more than 40 pounds have twice the risk of having a baby that weighs more than nine pounds at birth. And heavier babies pose delivery risks for both mother and child—including broken collar bones for babies and vaginal tearing and bleeding for mothers. Bigger babies are also more likely to be overweight later in life, which can lead to diabetes and other serious...