With my first baby I ran on the treadmill until I was too big lol.
Second bub, nothing as it was lockdown and he grew so fast I was so big so quickly that it was harder for my body to cope with doing too much.

I didn’t do anything too strenuous, just regular walks.

If you were already doing something, continue but in a safe manner. Otherwise walking

It depends on what level of exercise you were doing before falling pregnant. And also check with your GP as to what’s best. Walking is good for just about everyone