Carbon dioxide. Carbon dioxide (chemical formula CO2) is a colorless gas with a density about 60% higher than that of air (1.225 g/L) that is odorless at normally encountered concentrations. Carbon dioxide consists of a carbon atom covalently double bonded to two oxygen atoms.
You should only do ballet in pregnancy if you are used to it. Ballet stretches can place a lot of pressure on your joints, especially your pelvic joints, and standing on one leg can cause pain in your pelvis.
It is sometimes important to stretch daily for at least 10-15 minutes, to give the muscles ample opportunity to warm up, reducing the risk of injury. You should also stretch to wind down at the end of ballet dancing.