Carbon dioxide is a pure substance. A pure substance can be an element or a compound. Carbon dioxide is a pure compound, consisting of two kinds of atoms that are bonded together. An element consists of merely one kind of atom. For example, oxygen is an element.
For Downâs syndrome, a blood test called the quadruple test is available from weeks 14-20 of pregnancy. For Patauâs and Edwardsâ syndromes, you will be offered a mid-pregnancy scan that checks for physical abnormalities.
Find out when changes in... Low back pain during pregnancy. Learn what causes low back pain during pregnancy and what you can do to ease or prevent it. Headaches during pregnancy. Find out why itâs common to get headaches during pregnancy, how to soothe and prevent them, and when to call the doctor. Gas and bloating during pregnancy. Find out why you may burp, fart, and have more gas than usual when you're pregnant, and what you can do about gas and bloating...