• Q. My friend is blood type O+. He is planning to marry a woman whose blood type is O-. I heard that people of opposite blood types (+/-) should not try having children because it's dangerous. Is this true?

  A. NO! Although they have to be aware of a few facts, there is no reason for them not to have children together.

  Whether a person's blood type is "positive" or "negative" refers to whether they have a certain antigen sitting on their red blood cells (RBCs). The Rho antigen, commonly known as the RH factor, is only 1 of literally hundreds of possible antigens now identified on red blood cell walls.

  When a person who does not have this antigen sitting on their RBC (i.e the person is RH-) is exposed to blood that does have this antigen (i.e is RH+), like when receiving a blood transfusion, they respond by producing an antibody to it. It's like when you see something foreign to you, you protect yourself from it. These antibodies allow the body to attack the foreign substance and kill the cell, causing it to burst. That's why anyone with RH- blood (no antigen on their own RBCs) cannot receive a blood transfusion from someone with RH+ blood. In such a case, the donors RBCs would all be destroyed by the reaction of the recipients body to form antibodies and attack the foreign antigen. (Is this clear?)

  

  In the case of a mom and baby, it can be quite similair, because there is potential for the blood of the mom and baby to mix. It's only an issue when mom is RH-, as is the case with your friend. If both mom and baby are RH-, there's no problem. But when dad is RH+, there's a good chance baby will be RH+ as well (genetics we'll save for another time). In such a case, if baby's RH+ blood is mixed with mom's RH- blood, and her body reacts by producing antibodies against this foreign antigen, it is possible that these antibodies cross the placenta back to the baby and start "eating up" the baby's RBCs (ie bursting them). This will leave baby without enough RBCs and potentially quite sick (although a whole spectrum exists). We call this isoimmunization.

  What we can do, however, is try to prevent this from ever happening. We can do this by giving the RH- moms a vaccine which, basically injects them with the pre-formed antibody to the Rho antigen. That means that if such an antigen were to appear in their blood (say from their unborn RH+ baby), this injected antibody would do all the work to destroy it, and mom's system would not have to produce any of its own. In time, the injected antibody disappears (or is used up). But if mom was to react and make her own antibody, THAT antibody hangs around FOREVER. That would not only jeopardize this pregnancy (by crossing the placenta and destroying baby's blood) but any other pregnancy with an RH+ baby!!

  I know this can all seem confusing, and maybe this is more information than you wanted to know.

  BOTTOM LINE:

• RH incompatible parents can have babies together.
• This will not affect their fertility rate.
• All pregnant women should have a blood test to determine their blood types.
• All RH- women who become pregnant should receive this vaccine. (there's a whole timetable for when is the right time, etc.)
• For those who don't recieve this vaccine AND whose babies are affected by isoimmunization, good treatment exists. Although the rare case is severe enough to leave permanent problems in the baby, the vast majority of babies do perfectly well and live happily ever after.

  (Whew!)

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