I'm a male with O positive blood type. My girlfriend has AB positive blood type.

Are we medically compatible? Do we have good odds of having healthy offspring? Is there anything we should be aware of during pregnancy?

1 Answer 1


This is something to be confirmed by your doctor and I'm not sure why you're worried, but

ABO blood group incompatibilities between the mother and child does not usually cause hemolytic disease of the newborn (HDN) because antibodies to the ABO blood groups are usually of the IgM type, which do not cross the placenta. However, in an O-type mother, IgG ABO antibodies are produced and the baby can potentially develop ABO hemolytic disease of the newborn.


This means that you being O and her being AB is not an issue in terms of conceiving or carrying a baby.

You are both "positive" on Rh factor.

The hemolytic condition occurs when there is an incompatibility between the blood types of the mother and the fetus. There is also potential incompatibility if the mother is Rh negative and the father is positive. When any incompatibility is detected, the mother often receives an injection at 28 weeks gestation and at birth to avoid the development of antibodies toward the fetus.


You don't have a combination known to cause trouble, and if you did, there are treatments during pregnancy to prevent the trouble.

Why are you worried you might not be "medically compatible"? There doesn't seem to be any evidence that you are not.

  • 2
    Each biological parent donates one of their two ABO alleles to their child. A mother [or father] who is blood type O can only pass an O allele to her son or daughter. A father [or mother] who is blood type AB could pass either an A or a B allele to his [or her] son or daughter. biology.arizona.edu/human_bio/problem_sets/blood_types/… Aug 5, 2018 at 12:43
  • 3
    @ChrisRogers I'm not arguing, but according to the sentence above, the AB vs O of the parents "does not usually cause hemolytic disease" with the possibly exception of an O mother (which is not the case here) so the information in your comment isn't super relevant. Aug 5, 2018 at 13:35
  • Thank you everybody. I know I'm fine ... O type is very popular. But my girlfriend has AB which is not popular (only 7% of population). So I just wanted to double check before conceiving a child .
    – john
    Aug 5, 2018 at 14:12
  • @john ABO and Rhesus compatibility is only relevant regarding potential haemolytic disease of the newborn (as Kate mentioned above). There is not really any other relevance of this compatibility in life. Baby could be A, B or O positive. Your girlfriend is fortunate that she can (in simple terms) receive a blood donation from anyone. Interestingly though, Type O seems to protect a little from falciparum malaria, should you ever find yourself affected: pnas.org/content/104/44/17471 (always use malaria prophylaxis!)
    – Chris
    Aug 13, 2018 at 22:07

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