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.
Remember that the extra weight and your growing belly can affect your balance and may cause falls. In the earlier stages of your pregnancy, nausea and dizziness can also increase your chance of injury, especially if your job is very strenuous. The jury is still out on how much physical exertion at work is safe during pregnancy.