I'm 37 weeks and I weight train about 4 times a week. Just eight pounds and very slow, I also do an hour of cardio about 5 times a week, I've always worked out though. Ask ur doctor first, I didn't work out my first trimester also. Good luck.
Most doctors will say, if you were doing it before you were pregnant than its safe. But it depends on if you're a high or low risk pregnancy. I would hold off until your first appointment and ask your doctor just to be safe.