RH factor and Pregnancy
The Rh Factor
During your prenatal panel, blood will be drawn to determine your Rh factor. You will be either Rh Positive or Rh Negative.
There is no worry if you are Rh Positive (Rh+), but the importance comes in when you are Rh Negative (Rh-) and the baby’s father is Rh+.
Your baby is either Rh- or Rh+ as well, and there is increased risk if you are Rh- carrying an Rh+ baby.
In this case, if the mother and baby’s blood mix, the mother can develop antibodies against her next baby’s blood (there is rarely a problem with first babies). This can cause your baby to become anemic, have brain damage, develop jaundice, or even die.
How can blood mix?
- Amniocentesis
- CVS
- Abortion
- Miscarriage
- Hemorrhage
- ruptured placenta
- after your first baby’s birth (blood may flow back into your circulation from the placenta)
If you are Rh-, your blood may be tested at intervals throughout pregnancy, or after the possibility that the blood may have mixed (if you experience bleeding). You will be given the option to take the RhoGam injection between 24-28 weeks (your blood will usually be tested again at this time with the Coombs test, or titer test, to determine if your titer is rising or not) during pregnancy which will prevent your body from building antibodies against your baby’s blood should something happen in which the blood will mix.
If the mother is low risk and has not previously had a Rh+ baby, and her titer is not rising, she can reject the RhoGam injection during pregnancy and postpone it until after the birth, after the baby’s Rh factor has been determined. There is no need for Rhogam if the baby is Rh-.
The Rhogam injection given during pregnancy will transfer to the baby, and at this time we are not sure of long term effects of that.