If you are pregnant, you will have your first prenatal tests during
trimester. Every woman
has her blood tested at the first prenatal visit to see what her blood type is. If your blood is
Rh-negative, it will also be tested for
antibodies to Rh-positive blood. If you have
antibodies, that means that you have been
sensitized to Rh-positive blood. The antibodies can
now kill Rh-positive red blood cells.
If you are Rh-negative and your partner is Rh-positive,
your fetus is likely to be Rh-positive.
If you are pregnant or have
miscarried, or if you have had an elective abortion, a
partial molar pregnancy, or an
ectopic pregnancy, you will need testing to see if you
have been sensitized to Rh-positive blood.
At the first prenatal visit, your blood is
tested to see if you have been previously sensitized to Rh-positive blood. If
you are Rh-negative and test results show that you are not sensitized, a repeat
test may be done between 24 and 28 weeks.
If test results at 28
weeks show that you have not been sensitized, no additional tests for
Rh-related problems are done until delivery (barring complications such as
placenta abruptio). You will also have a shot of Rh
immune globulin. This lowers your chances of being sensitized during the last
weeks of your pregnancy.
If your newborn is found to be
Rh-positive, your blood will be screened again at delivery with an indirect
Coombs' test to see if you have been sensitized during late pregnancy or
childbirth. If you have not been sensitized, you will have another shot of Rh