I've gained 6 pounds in a week. i'm six months pregnant and i have been under weight is this normal?

Maybe: Rapid weight gain in underweight women in pregnancy is sometimes seen and usually isn't cause for alarm. However, it can also be a red-flag for pre-eclampsia. You need to advise your Ob and have your blood pressure checked. If your blood pressure remains normal, its not worrisome. Most weight gain occurs after 20 weeks gestation. It is recommended that an underweight women gain at least 28lbs