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Author Topic: blood group and marriage  (Read 18856 times)

Offline thecoolone

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blood group and marriage
« on: 21/01/2005 13:17:27 »
Can someone please answer this question for me. Can a B+ man marry an A- woman. I am really in a dilemma. Thanks


Offline chris

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Re: blood group and marriage
« Reply #1 on: 21/01/2005 18:39:59 »
Of course - to my knowledge the marriage rules don't demand a blood test first ! You can marry whomsoever you like (within reason) !

Seriously though, to be B+ means that you are either BO or BB; in other words you carry at least 1 B allele (gene), and either another B, or an O allele. The + refers to rhesus status (D). A rhesus positive person makes the rhesus D antigen in their blood.

For an A- woman she would have to carry either 2 A alleles, or 1 A and 1 O allele. If she is rhesus (D) negative she doesn't make the rhesus D antigen so she could make antibodies against it, if she wanted to.

This means that if you have children there is a chance of having a D+ baby. This is fine during the first pregnancy, but when the baby is born the foetal blood can mix with the maternal blood, exposing the mother's immune system to the D antigen. It responds by making anti-D antibodies (thinking that the D is a foreigner).

So when she becomes pregnant for a second time, again with a D+ baby, all goes well until about 36 weeks when the placenta starts to transfer protective antibodies from the mother's bloodstream into the baby. The idea is that the mother's antibodies protect the baby when it is first born until it has a chance to activate its own immune system.

The mother's blood now contains anti-D antibodies from her first pregnancy. These latch on to the baby's red blood cells, which (unlike the mother's blood cells) express the D antigen. The coating of anti-D on the foetal red cells flags them as 'bad' leading to them being destroyed.

This causes the baby to become anaemic and causes 'hydrops'. Babies with this need to be delivered and resuscitated quickly.

However, we stop this happening by giving rhesus-negative mothers a shot of anti-D antibodies at the time of delivery. These anti-D antibodies mop up all of the foetal cells and stop them kick-starting the immune system. That way the mother never develops anti-D antibodies, and her babies never have problems.

So, in answer to your question, no there is no reason why a B+ man and an A- lady shouldn't get married. Unless they are already married to other people of course !


"I never forget a face, but in your case I'll make an exception"
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« Last Edit: 25/01/2005 09:05:48 by chris »

Offline qazibasit

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Re: blood group and marriage
« Reply #2 on: 24/01/2005 20:01:05 »
well when an Rh+ person marries an Rh- women and after conception an Rh+ fetus starts developing in an Rh- mother. During pregnancy the Rh+ fetal blood is seperated from the Rh- maternal blood by the placental barrier. Therefore the pregnancy continues smoothly and remains uneventful. At the time of delivery when the placenta is detatched from the uterus some quantity of fetal blood inevitabily enters the maternal circulation. The Rh+ blood has strong immunogenic D antigens will stimulate maternal immune system and in few weeks anti D antibodies will start developing in the mother which will damage the blood of the next fetus and this is called as the Rh Incompitability, and to prevent it an injection of Rhogam is given before delivery. So it was complicated before but nowdays its just normal you can marry her.

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Re: blood group and marriage
« Reply #2 on: 24/01/2005 20:01:05 »


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