First thing is to make sure you are getting lots of rest and taking good care of your self! The better you take care of yourself, the better you will feel and then you are better able to do a job that may require you to stand for a long period of time.
I worked at Starbucks while I was pregnant and I loved it. I had to stand all the time but the days went by fast and they have great benefits.
Truth is that most of us have to work while pregnant and we just have to find a way to get through it.
You could also try any job that keeps you seated all day if you prefer that. Data entry, phone answering service. Maybe you can take a child or two into your home for after school care of day care?
Best wishes and remember to take care of yourself!
Tammy