If you are already working out, have a fitness routine that you regularly have been doing.. most doctors will tell you that you can keep right on up with it.. including lifting weights! I know there was a controversial article on women doing cross fit while pregnant.. but for ones that have been doing it.. their body adjusts and I personally think it is amazing to keep fit and healthy.. but always know your limits. I worked out up until about 9 months or over.. and did it help me.. ? YES! Completely..
I hate that sometimes we poo poo women who work out because we think it's unsafe.. but don't mind women who aren't active at all.. we should support those that want to stay active and do so in a healthy and safe manner.. your body is a wonderful thing if you tune into it! :)