Just after giving birth, your uterus is still hard and round (weighing about 2 1/2 pounds) and can be felt just by touching your naval. In about six weeks, it will weigh only 2 ounces and will no longer be felt by pressing on your abdomen. That mysterious brown line that you may have had down the center of your lower abdomen during pregnancy will disappear. But, unfortunately, those stretch marks you developed aren't going anywhere in the near future. Stretch marks tend to be bright red during and shortly after pregnancy, but they will eventually become more of a silver color and begin to blend in with your skin. Also, even the fittest moms will experience some flabbiness in the midsection after giving birth. Normal stomach exercises (such as sit-ups) can get your tummy as flat as it once was.