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.
Hives During Pregnancy. About 1 in 5 pregnant women experience changes in their skin during pregnancy, including acne, skin darkening, and stretch marks. Although women may feel self-conscious about these new âbeauty marks,â skin changes during pregnancy are a normal occurrence. Hives during pregnancy are less common, but they do happen frequently. Hives during pregnancy represent an allergic reaction to food, insect bites, medicine, chemicals, etc.