Natural Birth and Baby Care.com

Rhesus Factor

by George Tomy Mampilly
(India)

Rh incompatibility arises when mother is Rh-ve and the fetus is Rh+ve.
What if it were the opposite, the mother is Rh+ve and the fetus is Rh-ve. Would erthyblastosis fetalis occur in the situation above or something similar

You also mentioned in your article on "RH Negative (Rh-) - What does it mean for you?"
that a Rh-ve parents could have Rh +ve child. Could you explain, what is the genetics behind it.

Answer:

There don't seem to be any problems when the baby is Rh- and the mother is Rh+. It only occurs when the mother is Rh- and baby is Rh+

My information about two Rh- parents producing an Rh+ baby came from a visitor to the site who found herself in a confusing situation after her daughter was born Rh+. Here's the information from her letter to me:

"Finally, we ended up meeting with maternal-fetal medicine specialists and a geneticist who explained to us that yes it is possible to have a positive baby when both parents are negative (people come from such large gene pools and blood typing is so complicated that indeed the RH factor can pop up from somewhere when two people come together to have a child and bring all their different percentages of blood proteins to the table!!!)"

I don't know exactly the genetics behind it - I'm not a genetic specialist and don't even dabble in genetics as a hobby :) If you're truly interested I'm sure it's possible to find a geneticist willing to consult with you and explore more deeply, however. A university is probably a great place to start looking. I'm sorry I don't know the specifics for you!