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If Both Parents Have Same Blood Group What Will Be The Child's Blood Group?

Posted on Mon, 4 Feb 2013

Question: if both parents have type o neg. blood, and their first two children have o neg. blood, could a third child have o positive? what are the odds? one step futher, what type would a fourth child have?

Answered by Dr. Kalpana Pathak (2 hours later)

Hi XXXXXXX,

Thanks for writing to us.

Blood group is always genetically determined.

If both the parents are actually 'O-negative', all the children will be 'O-negative'.

Having said this, O negative parents can only deliver O positive child only if tests were "inaccurate".
Or if the father had weak rhesus D gene that is actually father is positive but tested negative due to weak Rh D gene. In these cases retesting should be done to rule out weaker reaction.

Hope that answers your query. Should there be further questions, I would be happy to assist you.

Regards

Above answer was peer-reviewed by : Dr. Prasad

Follow up: Dr. Kalpana Pathak (10 hours later)

if the father ha a weak rhesus D gene and the father a actually a positive, even though tested negative would the RH factor exisist for the childredn? espially for a second birth? (I know it as having a blue baby)

Answered by Dr. Kalpana Pathak (1 hour later)

Hi XXXXXXX,

Thanks for writing back.

If father has weak rhesus D gene that might pass to the offspring.
However for all practical purposes if both the parents are O negative, all the off XXXXXXX or children have to be O negative, provided the blood tests have been accurately done.

As a general rule, all rhesus negative persons should be tested for weak rhesus D gene as a person with weak rhesus D gene is actually rhesus factor positive.

Hope that answers your query.

Take care

Note: For detailed guidance on genetic screening consult a genetics specialist

Above answer was peer-reviewed by : Dr. Prasad