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.
Does Cramping Mean Miscarriage? Cramping during pregnancy can be scary, but is it a sign of miscarriage? What what you need to know... Of all pregnancy symptoms, cramping is one of the biggies that give most moms-to-be pause -- especially in the first trimester, when the risk of miscarriage is at its highest. A miscarriage can happen any time up to 20 weeks, but the vast majority occur before 13 weeks.