As a newly minted prenatal yoga teacher who is eminently qualified to teach pregnant students, you'll want to stay away from particular techniques. Poses that require women to rigorously twist their abdomens from side to side can ultimately compress this region of the body. During the first trimester, women should likewise avoid jumping in and out of asanas, headstands, handstands and other poses that require them to hold their bodies in a delicately balanced position for several seconds. As an instructor, you should also advise women to avoid abdominal work. Since the stomach area is designed to expand during pregnancy, women can forget about the “no gain, no pain” methods for training their abs until after the baby has been born. Compressing the fetus is just not in your baby’s best interest.