Why Would a Doctor Do Blood Tests on a Pregnant

Why would a doctor do blood tests on a pregnant woman?

A) To make sure she was actually pregnant
B) Normally, a doctor does urine tests on a pregnant woman, not blood tests.
C) To look for risky infections, diseases, or to screen fetal blood which gets mixed into the mother's blood
D) To prove paternity, or who the father of the fetus is
E) To look for risky sexually transmitted diseases or cancers