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.
Normal Early Pregnancy Cramps. Even though cramps can sometimes indicate problems, cramping in pregnancy is probably normal more often than not. As your uterus begins to grow, you can feel mild to moderate cramping in your lower abdomen or your lower back. This cramping may feel like pressure or stretching, or it may feel similar to menstrual cramping, but mild, transient cramping in early pregnancy is usually normal and not a sign of miscarriage.