I do train pregnant women, and I always have open communication with their physician. Michael has some great points and I agree with Karin as well. You need to make sure their HR doesn’t elevate too much and some light weight training with cardio will be enough to keep them in good condition. Some pregnant women respond better than others, so it depends on the client. I have trained pregnant women up until 2 days before they had their baby and then others for much less time. You can make her wear a HR monitor to keep checking her HR and keep communicating with her doctor if needed, so you can all be in the same page. Also, keep looking for any signs of discomfort when training her.