Can two people with the same blood group get married?

Question

Hi doctor,

I am 30 years old. I am planning to get married to a girl who is known to me. We have a very good understanding. But we have the same blood group, which is O-positive. Since the blood group is a factor in having babies, do you think having the same positive blood group could create problems for future generations?

My father is very concerned about this. He talked with several doctors, and they ensured that it could create problems. And they do not want me to marry this girl. I spoke with another doctor, and she replied that it is not a big problem.

I am in great trouble right now. How could I give a clear explanation to my father about this issue? My father told me he knows a couple of people with the same positive blood group who have been married for 10 years without having a baby. And doctors could not find any problems for either men or women. But their blood immune system did not match to have a baby.

I have these questions:

Does the same blood group create problems? If yes, then what basically creates problems?
Are there any precautions that need to be considered for having a baby after getting married to the same blood group?
Are diseases like thalassemia occurring because of parents' rhesus factors?

One thing to clarify is that we are two brothers and two sisters, and all six members of my family have the same blood group, O positive. My elder sister got pregnant after eight years, and her husband is B positive. And my younger sister always gets sick since the antibodies in her blood cells might not be strong enough to fight the disease.

My father explained that, due to my parents having the same blood group, my sisters might get the above-mentioned problems. I will explain my family based on your explanation.

Thank you in advance.

Answer 1

Hi,

Welcome to icliniq.com.

I read your query and understand your concern.

There are two major blood group systems and more than 400 minor blood group systems. The major blood group systems are the ABO system and the Rhesus system, which are important. In the ABO system, there are A, B, AB, and O. While in Rhesus, if it is present, it is positive, and if not, then negative.

You are of the O blood group with a rhesus positive. O positive is one of the commonest and oldest blood groups and is found in more than 50 percent of the individuals in the world. When the female is O negative, and the male is O positive, there is a future risk for the fetus with a condition called hemolytic disease of the newborn. If both are O positive, then there is no risk.

Now, regarding the girl known to you, if she is a close relative (second or third-degree relative), then the marriage can create a reduced genetic pool. Hence, future kids may have genetic defects, or you might not have kids at all due to a reduced genetic pool. It is not related to the blood group.

There are so many common genes amongst relatives, and some are suppressed. So, when they get married, these suppressions may get activated, and genetic abnormalities or diseases that are secondary to suppressed immune systems can be seen. If the girl is not a relative, then the blood group is hardly a concern. If both are O positive, it would not matter.

If she is a relative, get genetic tests to rule out any common diseases, which can affect the future kid. This test is called genetic counseling. Only among close relatives, the immune system behaves dangerously due to a reduced genetic pool.

To conclude, having a common blood group is not a problem. She can donate blood to you and you to her in emergencies, just like your siblings can. No other complications with the same blood group.

I hope this helps you.

Thank you.

Can two people with the same blood group get married?

Blood Group Compatibility and Genetic Risk Marriage Companion