Pregnancy is a time to understand and listen to your body. Any exercise that is beyond your comfort will definitely hurt and might cause injury which is not for you to do. Yoga which is gentle can be learnt in graded version from easy level. You should always listen to your body and never cross what your body and mind says. The yogic practices that involve vigorous physical activities belly down poses, deep twists, deep back bends, jumps and jerky movements, abdominal strengthening practices and certain Pranayama should be avoided.