If a mother has type O blood, and a father has type AB, their children will almost certainly have either type A or type B. Considering a mother of type O blood will begin to produce antibodies against both A and B blood after exposure to the corresponding antigen, does such a pregnancy ever cause Graft versus Host Disease?

What about in the opposite case, wherein a fetus has type O blood and the mother has either of type A or B?

  • I think I once read that antibodies targeting for the AB0-features don't pass the placenta, hence there won't be any problems for mother and child. However, I don't have a source right now, so just leaving a coment right now
    – Arsak
    Feb 27, 2017 at 7:03
  • Such antibodies are IgM and so don't cross the placenta which only allows IgG through. Feb 28, 2017 at 7:06

1 Answer 1


Very rarely, The AB father plus O mother scenario you describe can cause a disease: https://en.wikipedia.org/wiki/Hemolytic_disease_of_the_newborn_(ABO)

More commonly, Rh-positive father plus Rh-negative mother can cause a disease: https://en.wikipedia.org/wiki/Rh_disease

I can't find any reports of the mother suffering any ill effects from the baby's immune system. The likely reason for this is that fetuses don't make their own antibodies. They rely on the mother's antibodies. See: https://biology.stackexchange.com/questions/5782/at-what-age-do-babies-begin-to-synthesize-their-own-antibodies

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