Blood type changed during pregnancy

[Anonymous]

Anonymous wrote:

Anonymous wrote:

Anonymous wrote:

Anonymous wrote:

Anonymous wrote:

Anonymous wrote:I’ve heard of people claiming their blood type changed. I think most are simply cases of people misremembering or not knowing in the first place but thinking they do. My own husband was told by his parents that he was O- but found out that he’s actually O+.

Your blood type doesn’t randomly change. It is genetic. It stays the same throughout your life like your eye color.

Well your eye color definitely changes throughout life and not just from cataracts. Babies often have blueish or violet eye colors that turn hazel. And hazel eyed people’s eye colors change with their mood - if normally brownish they turn amber or green when they get mad or if normally green they turn blue when they get upset.

They can change from a lighter color to a darker color in infants and toddlers because babies do not produce much melanin when they’re first born. That’s why a lot of babies are born with blue eyes that later turn brown (for example). In those babies, it’s not really changing though because their eyes were always going to be brown based on their genetics. Brown is always their actual eye color that their genetics coded for. Once you have your final eye color, it does not truly change (unless you have some sort of medical condition). It’s simply an optical illusion.

That’s why I’ve always thought mothers were weird for asking how they can prevent their baby’s eyes from becoming darker (which I see often on mom forums). If their genes/alleles determine their eyes are going to be brown, then they’re going to be brown. You can’t stop it. The same applies to skin color and hair color.

I’ll never understand the societal obsession with non-brown eyes. I have always loved medium to dark brown eyes (the type that are pure brown with no yellow or green hue or any other color). The darker the brown, the better.

My eyes are hazel (a mix of light brown, green, and yellowish). I’ve never liked the color. I’m just grateful that my eyes function properly, though. The color of them is just a superficial thing.

Same here. I like eyes that are so dark brown you can barely see the pupil. 🤎👀

I’m Korean. Like 99% of our people fit this description, haha. It is plain for us. Koreans get excited if a baby is born with light brown eyes.

[Anonymous]

Anonymous wrote:I’m just wondering if anyone else has experienced something similar. I’m pregnant. Before pregnancy, my blood type was B-. I know this for certain because I have been a blood donor for years, and it says B- on my blood donor card and Red Cross app. When I had my blood drawn recently, I was told that I’m A-. My parents (also donors) are type B and type O, so it’s also genetically impossible for me to be type A. My doctor has told me that it’s not possible for your blood type to change if you have never had a blood transfusion or bone marrow transplant. She seemed sure that I’m A-.

It doesn’t really matter in the grand scheme of things, but my curiosity has been peaked. I wonder if pregnancy can cause something like this and if it will be temporary or permanent.

Beyond stupid. Your blood type is the same for life!

[Anonymous]

Anonymous wrote:

Anonymous wrote:I’m just wondering if anyone else has experienced something similar. I’m pregnant. Before pregnancy, my blood type was B-. I know this for certain because I have been a blood donor for years, and it says B- on my blood donor card and Red Cross app. When I had my blood drawn recently, I was told that I’m A-. My parents (also donors) are type B and type O, so it’s also genetically impossible for me to be type A. My doctor has told me that it’s not possible for your blood type to change if you have never had a blood transfusion or bone marrow transplant. She seemed sure that I’m A-.

It doesn’t really matter in the grand scheme of things, but my curiosity has been peaked. I wonder if pregnancy can cause something like this and if it will be temporary or permanent.

Beyond stupid. Your blood type is the same for life!

Please explain this then (link below). It would be awful strange for blood type results to be inaccurate that many times. The antigen testing that they use is highly sensitive and accurate, and multiple human errors are also usually caught.

https://www.tiktok.com/t/ZP8xfkSoR/

[Anonymous]

Anonymous wrote:

Anonymous wrote:

Anonymous wrote:I’m just wondering if anyone else has experienced something similar. I’m pregnant. Before pregnancy, my blood type was B-. I know this for certain because I have been a blood donor for years, and it says B- on my blood donor card and Red Cross app. When I had my blood drawn recently, I was told that I’m A-. My parents (also donors) are type B and type O, so it’s also genetically impossible for me to be type A. My doctor has told me that it’s not possible for your blood type to change if you have never had a blood transfusion or bone marrow transplant. She seemed sure that I’m A-.

It doesn’t really matter in the grand scheme of things, but my curiosity has been peaked. I wonder if pregnancy can cause something like this and if it will be temporary or permanent.

Beyond stupid. Your blood type is the same for life!

Please explain this then (link below). It would be awful strange for blood type results to be inaccurate that many times. The antigen testing that they use is highly sensitive and accurate, and multiple human errors are also usually caught.

https://www.tiktok.com/t/ZP8xfkSoR/

I have had 7 blood transfusions and my blood type has remained the same.

[Anonymous]

Anonymous wrote:

Anonymous wrote:

Anonymous wrote:

Anonymous wrote:I’m just wondering if anyone else has experienced something similar. I’m pregnant. Before pregnancy, my blood type was B-. I know this for certain because I have been a blood donor for years, and it says B- on my blood donor card and Red Cross app. When I had my blood drawn recently, I was told that I’m A-. My parents (also donors) are type B and type O, so it’s also genetically impossible for me to be type A. My doctor has told me that it’s not possible for your blood type to change if you have never had a blood transfusion or bone marrow transplant. She seemed sure that I’m A-.

It doesn’t really matter in the grand scheme of things, but my curiosity has been peaked. I wonder if pregnancy can cause something like this and if it will be temporary or permanent.

Beyond stupid. Your blood type is the same for life!

Please explain this then (link below). It would be awful strange for blood type results to be inaccurate that many times. The antigen testing that they use is highly sensitive and accurate, and multiple human errors are also usually caught.

https://www.tiktok.com/t/ZP8xfkSoR/

I have had 7 blood transfusions and my blood type has remained the same.

I had a blood transfusion in June of 2025. My blood type “changed” from AB+ to O+ (which is the type that I was transfused with). I was told that any change would be temporary, but my blood is still testing as O+ almost a year later (as of the beginning of February).

[Anonymous]

My husband and I are both A+. Our son is O+. Not sure how that happened.

I’m kind of disappointed that he doesn’t have the same blood type as either of us (because it’s nice to have things in common with your children), but it is what it is.

[Anonymous]

Anonymous wrote:My husband and I are both A+. Our son is O+. Not sure how that happened.

I’m kind of disappointed that he doesn’t have the same blood type as either of us (because it’s nice to have things in common with your children), but it is what it is.

You both had recessive O to pass along.

[Anonymous]

Anonymous wrote:My husband and I are both A+. Our son is O+. Not sure how that happened.

I’m kind of disappointed that he doesn’t have the same blood type as either of us (because it’s nice to have things in common with your children), but it is what it is.

There’s 6 possible genotypes when it comes to blood type - OO, AA, AO, BB, BO, and AB. Parents that are both type A can have a type O child if BOTH parents have the AO genotype rather than the AA genotype. You both inherited an A allele from one of your parents and an O allele from your other parent. The O allele is “hidden” because A dominates O.

OO = type O blood
AA and AO = type A blood
BB and BO = type B blood
AB = type AB blood

[Anonymous]

Anonymous wrote:

Anonymous wrote:My husband and I are both A+. Our son is O+. Not sure how that happened.

I’m kind of disappointed that he doesn’t have the same blood type as either of us (because it’s nice to have things in common with your children), but it is what it is.

There’s 6 possible genotypes when it comes to blood type - OO, AA, AO, BB, BO, and AB. Parents that are both type A can have a type O child if BOTH parents have the AO genotype rather than the AA genotype. You both inherited an A allele from one of your parents and an O allele from your other parent. The O allele is “hidden” because A dominates O.

OO = type O blood
AA and AO = type A blood
BB and BO = type B blood
AB = type AB blood

Explain how my kid is O when I’m AB and his dad is O. I don’t have an O allele to pass along. Yes, he’s our biological son.

[Anonymous]

Anonymous wrote:

Anonymous wrote:

Anonymous wrote:My husband and I are both A+. Our son is O+. Not sure how that happened.

I’m kind of disappointed that he doesn’t have the same blood type as either of us (because it’s nice to have things in common with your children), but it is what it is.

There’s 6 possible genotypes when it comes to blood type - OO, AA, AO, BB, BO, and AB. Parents that are both type A can have a type O child if BOTH parents have the AO genotype rather than the AA genotype. You both inherited an A allele from one of your parents and an O allele from your other parent. The O allele is “hidden” because A dominates O.

OO = type O blood
AA and AO = type A blood
BB and BO = type B blood
AB = type AB blood

Explain how my kid is O when I’m AB and his dad is O. I don’t have an O allele to pass along. Yes, he’s our biological son.

It takes TWO O alleles (one inherited from each parent) to have type O blood. A person with type AB blood (such as yourself) doesn’t have an O allele that their children can inherit from them, as their genotype is AB. Under normal circumstances, it’s impossible for a type AB parent to have a type O child (regardless of what the other parent’s blood type is).

The only 4 possibilities are that you or your son were typed wrong, your son has a weak A or B antigen, an extremely rare mutation occurred, or a switched at birth scenario happened.

[Anonymous]

Anonymous wrote:My husband and I are both A+. Our son is O+. Not sure how that happened.

I’m kind of disappointed that he doesn’t have the same blood type as either of us (because it’s nice to have things in common with your children), but it is what it is.

This is an understatement. People take being genetically similar to their children for granted until their child needs an organ or bone marrow transplant.

My son needed a kidney transplant and neither my husband nor myself could donate to him because we didn’t genetically match. He’s type A blood, and we’re type AB blood. That automatically disqualified us. It’s hard to understand how gut-wrenching getting that news is unless you experience it firsthand. Needing to rely on a stranger to save your child’s life is terrifying.