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.
Feeling tired is common in pregnancy. It's common to feel tired, or even exhausted, during pregnancy, especially during the first 12 weeks or so. Hormonal changes taking place in your body at this time can make you feel tired, nauseous, emotional and upset. Read more about tiredness in pregnancy.