Important Information on Blood Types of Parents and Children

There are two important facts about the blood types of parents and their children that are not widely known.  One of them caused an unexpected health problem in my family, and the other could have caused a much more serious problem but didn’t.

Please read the facts in red text, and click on the red links and read the information there, before asking questions in the comments.  I am not a doctor or any kind of expert on blood types, just an ordinary person who wrote an article to publicize information that I felt was not clearly enough presented to the general population.

UPDATE: Since I posted this article, I’ve seen that many of the people who read it are looking for information about which blood types can have children together.  Aside from rare mutations, a woman of any blood type and a man of any blood type can have a healthy baby together.

If the mother’s and father’s blood types are the same, this does NOT harm the baby.

In repeated Internet searches over three years, I have never found any report of any problem caused by parents having the same blood type–I have only seen people worrying about this possibility.  There is no reason to worry! If you want to know what blood type your baby might have, or if you are wondering how your blood type can be different from your parent’s, look at these handy tables. Now, back to our story!

No, I’m not talking about Rh factor.  The issue of “positive” vs. “negative” blood and how it affects pregnancy is well-known and mentioned in most books about pregnancy.  Here is a typical article about Rh factor.  Notice how it mentions antigens–the “letter” aspect of blood type, A, B, AB, or O–but then moves on, as if antigens aren’t important. What most people know about antigens is that they are important if you are receiving a blood transfusion.  Putting blood with A antigens into your body, if your own blood does not have A antigens (Type A or AB), will cause an immune response that can kill you.  The same is true for B antigens.  If you are Type O, both A’s and B’s are dangerous, so you should not receive a transfusion of any type other than O.  It is pretty quick and easy for medical professionals to determine a person’s blood type, so we don’t need to worry a whole lot about being given the wrong kind of blood, but just in case, it’s a good idea to know your blood type. These are the two things I didn’t know until after the point when it would have been medically useful to know them:

1. If both parents have the same blood type, that does not mean that all of their children also have that blood type.

(Any doubts I had about this being a poorly-understood fact were erased when I searched for a good online reference and found mostly discussion boards where people were confused about it!  Even some authoritative medical sources had explained the issue in a confusing or incomplete way.)  Here is a good explanation of how blood types are inherited.  The only sure thing is that if both parents are Type O, all their children will be Type O.  For the other types, there are other possibilities.

When I was about eight years old, my mother bought metal identification tags for my brother and me to wear when we were playing or bike-riding away from home, just in case we had an accident and were unable to tell rescuers our vital information.  My tag stated my name, address, telephone number, and “Blood Type A+”.  This was the first I had ever heard of blood types, and I asked if this meant I had the best type of blood. :-)  My mom explained about antigens and transfusions.  I went about my adventures, convinced that if I should ever need a transfusion, the doctors would read my tag and give me the right type of blood.

When I was sixteen, I donated blood for the first time.  I saw the Red Cross person write “O+” in the “blood type” box on the form.  I objected, “No, I’m A Positive.”  She said, “No, you’re not.  I just tested your blood.”  My emotional turmoil over whether I had been switched at birth or something was cut short by my friend Don, a future doctor who was a volunteer helping to run the blood drive, explaining to me that the A’s and B’s of blood type are dominant genes, so two parents with Type A blood may have genotype AO (one A gene and one O gene) and therefore have a 1 in 4 chance of having a child with genotype OO and therefore Type O blood.

My mother, who has a doctorate in biology, did a lot of forehead-smacking when she heard my news!  When my only sibling made his first blood donation a few years later, we learned that he also is Type O.  Luckily, neither of us ever has needed a blood transfusion anyway.

2. If a mother has Type O blood, and her baby has another type, the baby is likely to develop a dangerous level of jaundice after birth.

I do not understand why this fact is not in every pregnancy book, right alongside the topic of Rh factor!  I guess it’s because jaundice is easy to notice (baby’s skin turns yellow) and relatively simple to treat (expose baby to lots of ultraviolet light and give extra fluids), and there’s nothing you can do to prevent it.  Still, it would have been really nice to be informed of this possibility before my son was born because then I would have read about jaundice treatments and felt sure that the hospital was doing the right thing.  As it was, I just had to trust them.  Nicholas spent 24 hours in the neonatal ICU being bombarded with blue lights from three sides, receiving IV fluids and medication (I’m still not really sure that all that medication was such a good idea–the hospital didn’t tell us they were giving him anything other than water and electrolytes; we didn’t know until I received my itemized bill weeks later, and we never got to talk with a doctor about why those drugs; we only Googled them), getting a blood test every 6 hours, allowed to be held only for 10-20 minutes every 3 hours when I was nursing him, and that was traumatic for both of us!  I wish I had been prepared.

Here is some basic information on newborn jaundice, including an explanation of blood type incompatibility.  This article also explains why a breastfed baby who develops jaundice does not need to be given formula.

UPDATE: While pregnant with my second child, I was given the 2013 revised edition of The Baby Book by William & Martha Sears.  It now includes a thorough explanation of newborn jaundice and its causes.  Thank you, Dr. Sears!  Lydia also became jaundiced a few days after birth (and a few days before she started spitting up blood–it was quite a week!) but instead of going to the NICU, she was treated at Children’s Hospital in a regular inpatient room, where I was allowed to sleep in the room with her and feed her whenever she was hungry, and they didn’t give her any drugs.  It was a much better experience for both of us!  She recovered just as well as her brother without drugs.

If you have a choice, ask for jaundice treatment at home using a bili blanket.  If your baby’s jaundice requires more intense phototherapy and/or 24-hour monitoring, ask for your child to be admitted as a regular inpatient in a children’s hospital rather than to the NICU at a maternity hospital.  You’ll be more comfortable, and it will be less expensive for you and/or your insurance.  Also, ask to be informed of any drug that is administered to your child, and ask why it is being given.

I hope this information is helpful to other families!  Knowing it earlier would have worked for me.  Visit Mom’s Library for more helpful information for parents.

About 'Becca
author of The Earthling's Handbook, about the environment, parenting, cooking, and more!

174 Responses to Important Information on Blood Types of Parents and Children

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  2. Becky Brown says:

    But can a father with A+ blood and a mother with B+ blood have a child with A- blood.

  3. biggsis says:

    Very interesting. I did not know that a baby of another blood type with a type ‘O’ mother can have jaundice. We did not have to have extensive treatment – but my type A son needed some treatment. Thanks for sharing… I’m a nurse and I didn’t know that!

  4. Casey says:

    I had never read or heard of this blood incompatibility until my daughter was born either! I believe they should include this in the materials, etc. When preparing for a baby. My daughter wasn’t far from needing a transfusion & was in NICU for the first 4 days of her life. Thank God she got through it!

  5. Cassie says:

    If my mom has b+ and I have o- is that possible that I have negative blood and my mom have positive blood

    • 'Becca says:

      Yes, if you have had your blood typed (by a doctor, blood drive, etc.) and they said your type is O-, you have negative blood.

      It is possible for you to have negative blood and your mom, or even both parents, to have positive blood. Everybody has two genes for Rh factor, and if at least one of them is + you gat positive blood; it is only if both are – that you have negative blood. You get one gene from each parent. So if both parents have a + and a – they can have a child with two -. There is a nice chart explaining this in the article about how blood types are inherited.

      So don’t worry, your mom is really your mom! Merry Christmas!

  6. Loi says:

    Wow, someone has to be really living under a rock to not know that certain different blood types cant mix. Really!. Wake up!.

    • 'Becca says:

      That is why I said that what most people KNOW about blood types is that some types should not be mixed within one person’s body, in a transfusion.

      What I see in my Word Press stats on literally a daily basis (this is my most-read article ever) is that this fact has led many people to be confused about whether or not it is dangerous for people of different blood types to have children together. I am glad I can help clear up the confusion.

      • km says:

        I am o negative and so is my Hubby. Wee are expecting. I read online that because2 negatives equal a positive, that baby can be positive…? That’s not true is it? Because my dr haven’t have me the rhogam shoot because my Hubby is also o negative! Now I’m a little nervous with wondering if Red cross told my Hubby his correct blood type and if I need the shot… 2 weeks b4 due date i guess I’m nervous…thanks

        • 'Becca says:

          Talk to your doctor to make sure, but I am almost certain “two negatives make a positive” is a rule for math but not for blood types. Click on the link about how blood types are inherited for more info. Best of luck with your baby!

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  8. Holli says:

    I am O-, my husband and my 3 kids are O+. 2 of my kids suffered from jaundice; I wonder if the Rh factor contributes to that as well, as we both have O blood.

  9. Muzza says:

    Is it at all possible for a mother with A- and a father with A+ to have a child with AB+ blood

    • 'Becca says:

      I am not an expert, so please check the sources linked above…but if I understand correctly, no, a person with AB must have at least one parent who is either B or AB.

    • corie says:

      im confuse the obgyn told me my baby is ABO IVE never heard of it im RHpositive

      • 'Becca says:

        Ask the doctor what he/she meant. I have only heard “ABO” used as a shorter way to say “the aspect of blood that is A, B, AB, or O” and nobody can be all of those types at the same time. I’m not an expert!

  10. Maria Eva Choo says:

    both of my parents are blood type O and my brother and sister share the same blood type as my parents.however,I am a blood type B..What does that mesn,am I adopted?

    • 'Becca says:

      The charts I linked to do indicate that two Type O parents can only have O children. PLEASE talk to an expert before you accuse your parents of anything, though!

  11. Tuesday Mills says:

    If i have.A- blood and father has A+ is it possible to.have O- child??

    • 'Becca says:

      Yes. A and + are dominant genes. If each parent’s genes for antigens are one A and one O, you both have Type A blood, but when your genes are combined there’s a 1 in 4 chance of the child getting two O genes and therefore Type O blood. To have – blood you must have two – genes, but the father with + blood could have one + and one -, so when your genes combine there’s a 1 in 2 chance of the child getting two – genes and therefore – blood.

  12. Archismita says:

    Hi, You said you have type O blood and your son had jaundice and if a mother has Type O blood, and her baby has another type, the baby is likely to develop a dangerous level of jaundice after birth. So, it must mean your wife has type O. But, how can the child be anything but type O since you have already said that both parents with type O blood will have a type O kid? And how can the kid then have jaundice, since the blood type will be O, same as the mother’s?
    Really confused, and would like it if you cleared it up :)
    I’m glad to have stumbled across this.

  13. Rochelle says:

    My father has a B+ blood type and my mother is O+ and mine is A+. Is this possible?

    • 'Becca says:

      As I understand it, no. Talk with a doctor and make sure everyone’s blood type is identified correctly before you jump to any conclusions.

  14. EJ says:

    Both my parents are O positive and I just received notice from a blood donation that I am B positive. What?

    • 'Becca says:

      That is disturbing news. I think the first thing to do is make sure that your parents are correct about their blood types–it might be that they think they know but are mistaken, like my mom thought she knew that my brother and I were A+ without actually having had our blood typed.

  15. Peggy says:

    There are exceptions caused by mutations- Bombay phenotype or Para-Bombay phenotype is one of those…an AB- parent can have an O+ child under these circumstances..research mutation possibilities

  16. says:

    my blood group is o positive bt my sexual power is so high that i can’t maintain that’s why i am suffering a lot that can’t imagine.i am 21years old.i am not can it possible to maintain my high sexual power?

    • 'Becca says:

      I’m not sure I really understand what your problem is, but it doesn’t sound like it has anything to do with your blood group. Perhaps you should see a urologist. I hope you will find the help you need.

  17. liz says:

    my father is ab positive and my mother is ab positive im o negative can I be there daughter

  18. Apu says:

    My and my wife both are AB positive. Now, my wife is 3 months pregnant. Will there be any problem for the same blood group.

  19. juderose says:

    MY father and mother is type A+. and i am type AB+. how can this be??

    • 'Becca says:

      I am NOT an expert on blood types. You should talk with a doctor and make sure all 3 of you know your correct blood type. There may be a mistake, because as I understand it, to be AB you need at least one parent with an A and one with a B.

  20. nadia says:

    am a+ and my husband is also a+ and we r expecting a baby,can this have a negative effect on the baby?

    • 'Becca says:

      No, as far as I am aware, there are no negative consequences of parents having the same blood type.

      However, it’s important to understand that your child will not necessarily have that same blood type. As I said in the article, both my parents are A+, but both of their children are O+. Do not assume you know your child’s (or anyone’s) blood type without having it tested. The test is easy and uses just a tiny amount of blood.

  21. juderose says:

    ok.. thank you.. :))

  22. Judy says:

    I am 0-, and 3 of my 4 kids do not have type 0 blood. None of them had any issue with jaundice.

    I guess we were just lucky?

    • 'Becca says:

      Yes, as I understand it the jaundice is not a certain thing. It’s just more common when the mother is O and baby is another type, than it is for newborns in general.

  23. klhaden says:

    both my parents are O+ and i am it possible????? even it is just 1%

    • 'Becca says:

      Let me repeat: I AM NOT AN EXPERT ON BLOOD TYPES. I have learned (from the commenter above, and then a little reading on the subject) that there are some genetic mutations that can cause an apparently impossible blood type. These mutations also mean that it can be dangerous for you to receive a blood transfusion, so PLEASE consult your doctor.

  24. amandah says:

    good luck friends my question is, is it possible 4 biological children 2 hv diferent blood groups?

    • 'Becca says:

      Yes. In fact, if one parent is Type A and one is Type B, it is possible for them to have 4 children with all different blood groups.

  25. rajesh says:

    is there any possibilities that parents blood group o positive and ab positive and the child group is ab positive

  26. hassea says:

    My blood group is O+ and genotype is AS and my wife is B+ and genotype is As what could our child blood group and genotype be

    • 'Becca says:

      I hadn’t heard of genotype AS. After looking it up, I did not find any really good information, but from what I understand this means both of you are carriers of a gene S for sickle cell anemia. When each parent has one copy of a gene, usually there is a 1 in 4 chance of their child getting two copies of the gene and therefore expressing the recessive trait, in this case having sickle cell anemia.

      I think you need to talk with a genetic counselor about the risk of sickle cell anemia and if there is anything you can do to prevent it. Good luck!

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  28. Jackie Saulmon Ramirez says:

    I had the Rh factor which means I had to get a RhoGAM shot after every delivery.

  29. Dez says:

    I didn’t know about this either. I had read about the Rh factor. Thank you for sharing this. My daughter just had a baby and the same situation. Mom is O+ and baby is B+, so they are treating her as well.

  30. Hilliary Tanner says:

    My mother was O-, my Father was A+ I am A-, Now both of my Kids are O-, that being said, a couple of questions… First, would that mean my husband would have to be type O or does it skip a generation and they inherited it from my mother. Is it normal to “produce” 2 O- children like that since the type is somewhat hard to find?

    • 'Becca says:

      Type O is not that unusual. All it takes is an O gene from each parent. If you have one O and one A, your blood is Type A because the A is dominant–same thing for B with O–but you can pass the O to your children. The links in the article explain more about this.

      Because your mom had two O genes, whether your dad had AA or AO, you got an A from him and an O from mom. Your kids then got your O along with an O from their dad. So his blood type is something that has an O–could be anything but AB.

      For the + and -, the + is dominant, so you must have two – genes and therefore that is all you can pass to your kids. if your husband has + blood but has one + and one – gene, each of your kids had a 50/50 chance of getting two -. If he also has – blood, then the two of you can have only – kids.

      Follow the links in the article for handy charts that better explain all this.

      • km says:

        My mom was o+ dad a- 3 out of 7 of is are o- my hubby is o-and so am I. But drs want to automatically hand out the rhogam shot as precaution. Oh well I refused ive only been with my husband & guess what my son is o negative. So those rules do not make that the only senerio. 3 of 7 of is are o negative with o and a parents

        • 'Becca says:

          I don’t see where any of your family is an exception to the rules. Two O- parents can only have an O- child (so you are right there was no need for you to take Rhogam). An O+ and A- can have O- children; the odds can be as high as 1 in 2.

  31. Jun says:

    I’m just curious but it possible for my blood type to be O if my dad is AB and my mom is B (based off what they say). Just wondering cause I donated blood and got the result of it as O+.

    • 'Becca says:

      A parent with AB blood cannot have a child with O blood unless there is a mutation. Make sure your parents are correct about their blood types. If they are, talk with your doctor. It’s important to know if you do have one of these mutations because it would affect your response to a blood transfusion if you ever need one.

  32. Ma. jenessa Marcojos says:

    If the father does not have the same blood like the mother..what would happen..there child Is it there child?is it needed that the both parents should have the same blood?

    • 'Becca says:

      The articles that I linked explain all the details. Any two blood types can combine. Having different blood types does not prevent two people from having children.

  33. naveen says:

    my doubt was a’m having o+ Blood and my wife also having o+ Blood it’s any problem for my child

  34. baby says:

    my husband having b+ and me o+ is it possibe my son has o- blood

    • 'Becca says:

      Yes. Look at the tables in the article I linked: An O parent and a B parent can have an O child. Two + parents can have a – child. So an O+ and a B+ can have an O-.

  35. Kavi says:

    my father and my mother’s blood group are B+ and A+ respectively and I am having O+. Is it possible?

    • 'Becca says:

      Yes, it is possible. If you read the articles I linked you will get the full explanation. The short version is that A and B are dominant, so a person with genes AO has Type A blood and a person with genes BO has Type B blood, but because each of them has one O gene they can have a child with genes OO who has Type O blood.

  36. Dan says:

    Hey. I have blood type O + and my wife type O- . What must we do before we have children and after birth?

    • 'Becca says:

      I don’t know of any concerns after birth. Your wife may need medication during pregnancy because of the Rh factor (- vs. +). Click the link of Rh factor in the article for more info.

  37. Rachel says:

    I wish the doctors would have told me about some if these things.. My son was born with B+ blood type n I have O+… My baby never got jaundice but I had the worst headache n my neck n back were locking up where I could barely move… The doctors n nurses never told me but this was caused by my son having a different blood type than me n I had a csection so when they cut his cord some of his blood must have mixed with mine.. It was very painful….

  38. Lexie says:

    Hi, I am wondering can a mother with type A+ blood and a father with O- blood produce a child with AB+ blood?

    • 'Becca says:

      No. The A mother needs a B father to produce an AB child.

      • Just a person says:

        It can be possible with the Bombay Phenotype. However, it is extremely rare.
        The father would have to have two hh mutations with the mother passing on an H revealing the fathers hidden B.
        To the best of my knowledge there is no test for the Bombay Phenotype. In the event of such a blood type outcome DNA testing would provide the only true answer.

  39. Darla Lane says:


    • 'Becca says:

      I don’t understand your question–I don’t know what the DU means. I am not an expert in this at all. I hope you find a geneticist who can explain it.

    • Just a person says:

      The A- is from the A being dominant to the O and inheritance of one – from each parent (Each parent was a negative carrier +- ). You have the Duffy factor. Unfortunately I don’t know much about it. But here is some basic info that I found:

      Du Factor (Duffy Factor)

      The Du factor is related to the “Rh group” of blood factors. This is important because in some cases where the Rh group is missing (Rh-), the Du factor may be present. In these situations, the Du factor usually compensates for the lack of other Rh factors. This causes the blood stream to respond as if it where Rh+. When this situation occurs the person would be reported as Rh- Du+. These women are rarely at risk for Rh problems. Most often they are treated as if they are Rh+, unless they are getting a transfusion.

      So it makes you: Bloodtype A RH- DU+

  40. darwin hipol says:

    kinly help me,im a b+ and my wife is type o,what should be my son’s bloodtype?thank you

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  42. jane says:

    I would like to know if it is a problem if you are o+ and your husband is o+ will it affect the kids ?

    • 'Becca says:

      No, then your kids will all be Type O (but could be + or – because – is recessive) and it will be no problem.

    • mc says:

      Your child will be o positive. The rhogam shots are intended only for o/rh negative Mothers . Negative blood doesnt really hold protein like positive does your children will be fine.

      • 'Becca says:

        You are right that Jane will not need the Rhogam shot. However, it is possible that Jane’s child could be O- instead of O+, if both parents carry a recessive – gene. O- blood is fine to have; I just mention it so Jane will not assume she knows her child’s blood type without testing.

  43. My father was 0+ and my mother was AB RH -. I’m A+ and my husband was O+. Wh had an A- son. Is this possible?

    • 'Becca says:

      Yes, all of the above is possible. Baby gets one “letter” and one + or – from each parent, for the genes carried in baby’s cells. A and/or B dominates O, and + dominates -, in creating the blood type.

      Your father had to give you an O and could give you either + or -. Your mother could give you an A or a B and had to give you -. You must have gotten O and + from your father, A and – from your mother. The A and + are expressed in your blood type, while the O and – are hiding in your genes.

      You then pass one of your letters and either the + or the – to your child. Your husband, like your father, had to give an O and could give either + or -. Your son must have gotten A and – from you, O and – from your husband. The A is expressed in his blood type, and because he has two – and no + his blood is -.

  44. UNKNOWN says:

    I have read many of your articles. I have one question…if a person is B+ and both their parents are O+, is this possible??Could the person with B+ have the bombay blood group??

    • 'Becca says:

      I am not sure about the Bombay blood group. I really don’t know much about it. Normally, two O parents cannot have a B child. Talk to your doctor. I’m not an expert!

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  46. Milla says:

    Hi, can a mother A+ and the father AB+ have a child with blood type A- ? Thank you

    • 'Becca says:

      Yes, because negative is caused by a recessive gene. If you have one positive gene and one negative gene, your blood type is positive. If you have a child with someone who also has one positive and one negative, the child gets one gene from each parent, so it can get two negative genes and therefore have negative blood.

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  48. Promise Edem says:

    pls am blood group B positive and my fiancee is blood group O positive can we marry and produce healthy children without any sickle cell anaemic children to?

    • 'Becca says:

      Sickle cell anemia is genetic but not caused by the same genes that cause blood type, so your blood type does not tell whether you are sickle cell carriers. If there is a history of sickle cell in both your families, or if you are concerned because you belong to ethnic groups with high rates of sickle cell, you can get a blood test to see if you are carriers of the sickle cell gene; ask your doctor about “genetic counseling” to get a referral. It’s only if BOTH of you are carriers that you could have a child with sickle cell.

      I’m guessing from your spelling of fiancee (that spelling is female; “fiance” is male–but not everybody knows that) that she is female and you are male. In that case, your blood types are like Daniel’s (B+) and mine (O+) so your child would have a high risk of newborn jaundice. However, that is not a serious problem as long as you get treatment (see info in my article). If you’re the other way around (B+ mother and O+ father) then I am not aware of any complications that can result from your blood types.

  49. rajeshsoni says:

    CanfatherB+ and motherA- have a child B+ or O+blood

    • 'Becca says:

      Yes, both are possible. In order to have Type A, you need only one A gene; the other can be O. In order to have Type B, you need only one B gene; the other can be O. In order to have +, you need only one + gene; the other can be -. So, in this case the father’s genes must be a B and an O and at least one +, while the mother’s genes must be an A and an O and two -. Each parent passes one gene for A/B/O and one gene for +/- to the child. One child got B and + from father, O and – from mother, so has B+ blood. The other child got O and + from father, O and – from mother, so has O+ blood.

  50. iwaloju sherif says:

    is their any compatibility possibility for A+ and B+?

  51. kavita soni says:

    A-wife&B+husnandhusband blood group cross have a child blood group

    • 'Becca says:

      Their child could have ANY blood type! The only potential problem is if the child’s blood is positive, because the mother’s is negative, she will need to receive a Rhogam injection before the birth to prevent the baby from developing anemia.

  52. Ashley says:

    So, I am A+ and my husband is B+. What are the possibilities for our children? We had our first son in 2013 and are currently expecting #2 in July. Our son had jaundice at birth but not a serious form. If both parents are positive, will the kids be positive as well? Btw, my mom always told me I was 0+, it wasn’t until I gave blood for the first time in high school that I found out I’m A+. Hubby is military so we also know for a fact he’s B+.

    • 'Becca says:

      Click through to the article for all the possibilities. There is an up to 25% chance of your having a – child, because + is a dominant trait, so if you have a + gene and a- gene you have + blood but can pass the – gene to your child; if your husband does the same, your child has two – genes and therefore – blood. But this will not cause any problems.

  53. Nyamekye says:

    Please are there complications with an O+ man and A+ woman being together and bearing children?

  54. pardiprai says:

    I came across your article and felt like I had to write back. Thank you for sharing your story, it sounds identical to what had happened to me a both of my pregnancies…

    I really wish they did they had a book on abo incompatibility years back, but good to hear that more women are now educated about this.

    • 'Becca says:

      Yes, although it’s in the Dr. Sears book now, it still wasn’t mentioned in any of my prenatal care the second time around, either. I feel that’s almost negligent–why not make it routine to hand Type O mothers a pamphlet about jaundice??

  55. how we find blood group of baby if male B + & female A+,,,,which type of group should be got to children

  56. Jennifer Flores says:

    I am O+, my husband is A+. All of my children are A+ except one. He is AB-. From everything that I have read, that is impossible. I have no doubt who the father is because I have only been with one man. Should I assume that someone was typed incorrectly?

    • 'Becca says:

      I think you should start with that assumption but get your child’s blood type tested again. It’s best to know the correct type.

  57. anusha says:

    What happens to child if both mother and father have same blood grp?????

    • 'Becca says:

      That will be a normal, healthy child (unless there is something wrong that is not related to blood group). THERE IS NO REASON THAT PARENTS OF THE SAME BLOOD GROUP CANNOT HAVE A CHILD TOGETHER. This is clearly stated at the beginning of the article–did you read it? I have edited to make that fact appear in red text so it is more noticeable.

      I have seen in the comments on this article that many people of Indian ancestry are worried that having the same blood group is a problem. I am curious where you get this idea. I had never heard anyone worrying about it before I wrote this article.

  58. Rama krishna says:

    If the parents both have B+ve blood group, is there any problems in child.

  59. amin says:

    if mother and father are both b+ its possible to have a Daughter with o+?

  60. Partha says:

    I am B-ve and my wife B+ve, is there any problem in our baby ?

  61. harry logans says:

    i think have learnt a lot thank you

  62. Jessica says:

    If I’m b+ and my baby daddy is 0- and my child is a+ is that possible!?

    • 'Becca says:

      No. Neither you nor your baby daddy have an A gene, so you can’t have a Type A baby. Talk with your doctor and make sure everyone’s blood type was identified correctly.

  63. katy says:

    is it possible for me to be related to my family? My mom is A+ dad same brothers same half sisters same grandmother mom side same grandma dads side same grandpa moms side is B and grandpa dads side unknown I am O+ from what a Harvard link told me there is only a 1% chance. other facts I have auburn hair bone white skin hazel eyes my mom is European colored my dad naturally tan moms hair is black dad red moms eyes brown dads blue green my brothers black hair brown eyes my 1 half sister red hair blue eyes my other black hair brown eyes my grandpa black hair blue eyes my grandma black hair brown eyes my other set of grandparents brown eyes and red and brown hair. I swear I am the whitest family member. my cousins have red hair blue eyes my aunt blond with blue eyes her husband red hair green eyes. i am seriously the black sheep in terms of features and blood type.

    • 'Becca says:

      I’d like to see that Harvard link, because your blood type does not sound implausible to me at all. As I said in the article, both my parents are A+, yet both their children are O+. Many people with Type A have only one A gene and one O gene; many people with Type B have only one B gene and one O gene; when any two of these people have a child together, there is a 25% chance of the child getting two O genes and therefore having Type O blood.

      Hair, eye, and skin colors are more complicated genetically. From what I’ve seen in families, you don’t sound implausible at all; it’s just that your very light skin is at the extreme end of your family’s range of normal. Red hair is particularly quirky genetically. Since you have one parent with black hair and one with red hair, your having auburn hair (in between) makes sense, and the same for hazel eyes (in between brown and green).

  64. jaemariem says:

    I had a quick question. So I have O+ (I’ve been tested and donated blood so I’m sure) and my parents have done the same. But my mom is A+, and my dad is AB-. How is it possible for me to have O+? I thought it was cool, but it’s kinda strange.

    • 'Becca says:

      Talk to your doctor. The only way for an AB parent to have an O child is some type of mutation; if you (and/or your father) have one, that could be important to know.

  65. ziggy willian says:

    first i thank you for your wisdom and understanding to share with the world your knowledge. so i have a blood group of O positive so what is my genotype and the normal genotype and blood group for my choosen a pertiner. just to avoid skillcell or sick kid. thanks.

    • 'Becca says:

      Your genotype for antigens must be OO because only people with two O genes have Type O blood.

      I can’t tell you your genotype for Rh factor. It could be +- or ++.

      Sickle cell anemia is genetic, but the genes involved are different from the ones that determine blood type. Talk to your doctor about getting your blood tested to see if you carry the sickle cell gene. If you do, you want to choose a partner who is not a carrier, adopt children, or brace yourself for a 1 in 4 risk of your child having sickle cell. But if you are NOT a carrier, your child cannot have sickle cell regardless of your partner.

      My guess is that you are the potential father? If so, you do not need to worry about jaundice caused by blood type incompatibility because Type O fathers do not cause this problem.

      Because you have + blood, if you have a partner with – blood, you could have a child with a serious iron deficiency at birth. However, this is easily treated before birth by giving the mother a Rhogam shot, so it’s not a reason to reject a woman with – blood.

      Please click all the red links in the article for more information.

  66. Samuel Arthur says:

    i am o positive and my wife is o negative, will this have effect on our child? what can be done?

    • 'Becca says:

      Please read the article! It answers your questions! Especially, please click the link “Here is a typical article about Rh factor.” The only issue for you is that your wife may need the Rhogam shot.

  67. hundrah says:

    my husband is o+ and I m o-. can this affect our chances of giving birth

    • 'Becca says:

      PLEASE READ THE ARTICLE. There is no combination of blood types that reduces the odds of having a child. The only likely complication from your blood types is that you may need a Rhogam shot.

  68. Misty Hafiz says:

    realy ur article is helpful may God bless u

  69. benjamin oware says:

    we were having dicussion on blood group and we were saying that blood group of the same cannot marry,does why i was asking that question and because of that i have loose my wife when she noticed that i am a b positive and she was also a b positve

    • 'Becca says:

      I am very sorry that your wife believed this stupid rumor rather than learning the truth. It’s already in the article, which I hope you read, but I will repeat:


      Please, every time you hear anyone saying that people of the same blood group cannot marry, please speak up and tell them it is NOT a problem.

    • 'Becca says:

      Could you tell me WHY you and your friends were saying that people of the same blood group cannot marry? What is it that you thought would be wrong about it?

  70. abigail says:

    Hi My brother had a girlfriend that he dated for 2 months and she fell pregnant. upon a visit to the doctor she was already 3 months pregnant, but they only dated for 2 month at the time. Upon the arrival of the baby a paternity test was done and the test confirmed that it was his baby. Months later we notice that my brother and the girlfriend belong to the same blood groups.
    can you please explain if there is any possibility that the baby might not be his because the father and mother belongs to the same blood group.

    • 'Becca says:

      A paternity test compares the father’s DNA to the baby’s DNA. DNA testing is very close to 100% reliable. DNA is unique to each individual person (except that identical twins have the same DNA).

      Blood groups are NOT a good way to determine paternity because there are only 8 different blood groups among all human beings. If a baby’s mother had more than one partner in the month she got pregnant, it is really pretty likely that both partners have blood groups that could have combined with the mother’s blood group to produce the baby’s blood group. Click on “look at these handy tables” in the article and you’ll see all the options for combinations.

      The fact that your brother and the girlfriend are in the same blood group is MEANINGLESS here. What is suspicious is that her pregnancy began before he began “dating” her. If he had sex with her a month before they started dating, that explains it! Otherwise, either the doctor was wrong about the timing of the pregnancy or somebody lied about the paternity test.

      Repeating the paternity test is the best way to be certain.

  71. Adriana Ramirez says:


  72. Mike says:

    I realize this is a stupid question however I have O- and my wife has B+ and all 3 of are children match my wife’s blood typeB+, why is that?

    • 'Becca says:

      B and + are dominant genes. That means that if a child gets a B from one parent and an O from the other parent, the child has B blood; + from one parent and – from the other, the child has + blood. Your genes are still there in your children and could combine with recessive genes in your children-in-law to make grandchildren with your blood type. Click the links in the article for more information.

  73. LO says:

    My mother, father and brother are A+, and I just found out I’m O+…
    Would that mean both parents have the AO genotype or can just
    one have that to have a child that O+ ?

    • 'Becca says:

      Type O requires genotype OO, so both of your parents must be AO. It’s the same with my parents.

      • Lo says:

        Thank you so much Becca,
        My parents think the lab is wrong until I showed them the Bloodtype tables…I have one more unusual question.. In the 60’s, 70’s and 80’s my dad test O+, it was on his military dog tags, in1999 when he went in for surgery they said he is A+… He argued with the doctor and they tested again and it was A+ again.. He’s still confused and so was the doctor.. Any reason that can happen? He has never has transplants or any surgery prior to that.

  74. salman says:

    If the father is B+ and mother is B+ can there daughter will be from o group

  75. chinni.. says:

    If mother is A+ and father is B+ ,first pregnancy – baby girl , but doubt on second pregnancy ,Is anything problem with second pregnancy

  76. vijay arora says:

    35 Male nd her blood group are o+ nd her femal kid blood group are also o+then what should be hapend in next …any complication about pregnancy

  77. Sandrafawaz says:

    if iam blood type o positive is it dangerous to marry a man with blood type A positive?

    • 'Becca says:

      No. PLEASE READ THE ARTICLE as it has all the information you need. If you have children, there is a chance of newborn jaundice, but it is easily treated.


    Sir/mam my and my husband blood group is O positive and my chid blood group is B positive is this correct because I have read the article that if both parent have O poditive then child must be O positive plz reply

    • 'Becca says:

      It would also be possible for your child to be O negative, but it is true that you cannot have a B child unless there is a mutation. Talk to your doctor about Bombay Phenotype or other possible causes.

  79. Fatou badjie says:

    Hi, I am B+ and my hubby is 0 am due to have a baby in March 2015. What does that mean for our baby? cos this is our first baby, is our baby at risk of having sickle cell? And what those that mean for our genotype?

    • 'Becca says:

      Please click on the link in the article for an explanation of your child’s possible blood types. I am not aware of any health problems that result from your combination of types. Sickle cell is genetic but comes from different genes than the ones that determine blood type. Ask your doctor about blood testing to see if you carry the sickle cell gene.

  80. Adarsha Mamdal says:

    I have negative Rh factor. what mat be the Rh factor of my wife ?

  81. Alyssa says:

    Is it possible for my baby to have AB+ blood type and me to have B+ and my boyfriend to have O+ ? AB runs on my dads side of the family.

    • 'Becca says:

      It is only possible if your boyfriend is not the father of the baby. AB comes from one parent having an A and one parent having a B in their blood type (look at the charts I linked to) so if you are sure your boyfriend is the father, most likely someone’s blood type was reported incorrectly.

  82. Emma Owe says:

    Hi. I am 33 years old and of O+ blood group and may husband is O-.
    In March 2014 I devastatingly had a still birth with our first child.
    We have been trying ever since for myself to conceive, however I seem to be struggling to fall pregnant.

    Can it be that me being a + is fighting his – and therefore resisting me getting pregnant?
    I have heard that + and – rhesus factors are not such a problem with the first birth, but I did not receive any treatment after the birth.
    Could this be the reason we are finding it difficult?

    Thanks in advance.

    • 'Becca says:

      I am so sorry you had a stillbirth! I don’t think your combination of blood types is a problem or that any combination of blood types causes difficulty conceiving, but I AM NOT A DOCTOR, so it’s best to ask your doctor about this.

      Rh factor is a problem when the MOTHER is – and the FATHER is +. Since you and your husband are the other way around, that would not be the problem.

      I hope that you will soon have a healthy baby!

  83. sam says:

    In biological marriage which type of blood group in male and female is not accepted ? plz tell me soon

    • 'Becca says:

      I’m sorry, I don’t even know what you’re talking about. ANY combination of blood groups can be married and have children together. Please read the article!

  84. sanjana says:

    i have o+ and my husband has ab+ . what all complications are there in my pregnancy and in new baby.. apart from jaundice any serious problem ??

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