Anonymous
Post 01/25/2026 12:12     Subject: Blood type changed during pregnancy
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.

OP it ABSOLUTELY matters in the grand scheme of things. It is unfortunately not uncommon to lose a lot of blood during delivery, in which case you will need a blood transfusion. A transfusion with the wrong blood type can kill you. Figure this out ASAP - you never know if circumstances will require a surprise early delivery.


PLUS they didn’t do the correct blood test - so she doesn’t know if she is at risk of gestational diabetes.

What do you mean by “correct blood test”?
Anonymous
Post 01/25/2026 12:08     Subject: Blood type changed during pregnancy
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.
Anonymous
Post 01/25/2026 12:03     Subject: Blood type changed during pregnancy
Anonymous wrote:It sounds like your blood type is actually A-. A doctor’s office would be more meticulous and reliable than the Red Cross.


“it sounds like” is NOT a satisfactory answer here given the risk. Maybe she was wrong all along but this needs to be definitely resolved through another test and the Dr needs to take it seriously.
Anonymous
Post 01/25/2026 11:59     Subject: Blood type changed during pregnancy
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.

OP it ABSOLUTELY matters in the grand scheme of things. It is unfortunately not uncommon to lose a lot of blood during delivery, in which case you will need a blood transfusion. A transfusion with the wrong blood type can kill you. Figure this out ASAP - you never know if circumstances will require a surprise early delivery.


PLUS they didn’t do the correct blood test - so she doesn’t know if she is at risk of gestational diabetes.
Anonymous
Post 01/25/2026 11:54     Subject: Blood type changed during pregnancy
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.

OP it ABSOLUTELY matters in the grand scheme of things. It is unfortunately not uncommon to lose a lot of blood during delivery, in which case you will need a blood transfusion. A transfusion with the wrong blood type can kill you. Figure this out ASAP - you never know if circumstances will require a surprise early delivery.


This. A doctor should absolutely be double checking this. A mistake about her blood type could be deadly.
Anonymous
Post 01/25/2026 11:52     Subject: Blood type changed during pregnancy
It sounds like your blood type is actually A-. A doctor’s office would be more meticulous and reliable than the Red Cross.
Anonymous
Post 01/25/2026 11:51     Subject: Blood type changed during pregnancy
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.

OP it ABSOLUTELY matters in the grand scheme of things. It is unfortunately not uncommon to lose a lot of blood during delivery, in which case you will need a blood transfusion. A transfusion with the wrong blood type can kill you. Figure this out ASAP - you never know if circumstances will require a surprise early delivery.
Anonymous
Post 01/25/2026 11:44     Subject: Blood type changed during pregnancy
This mistake someone made is a big deal and can kill someone switch practices and have them retype you.
Anonymous
Post 01/25/2026 11:37     Subject: Blood type changed during pregnancy
Order an at-home blood type test from Amazon! That is how I found out the blood types of my son and daughter when I wanted to know. I confirmed the tests were accurate by having my husband (who knew his blood type beforehand) take it as well.

https://www.amazon.com/Pack-Eldoncard-Blood-Type-Test/dp/B013F5PAV0/ref=mp_s_a_1_4?dib=eyJ2IjoiMSJ9.H1WIh3fZsUJnN4nJu6HeLlV9ig_AlQm3lMUkrafE-W0d_nqbi_HtK9fAwS3J2xOuS2zmRKqf89rgY2okM4Una-kowW9c0fL2OPxQxlLzkdtszy_ZS3ZSon_pkoBjfY1FpAWtIIulaiPll15XuHyoFEjK-1WdkxA_w4rdjs3UFrJ3tdSXXxc0FZFb9ebNKC16LMf4-BLejQ_1MMjSb2ox5w.ZBREMe_s-YquKh7PEI8doGuOR40P5LgyC2_B6Zbr-_I&dib_tag=se&keywords=home+blood-typing+kit&qid=1769358296&sr=8-4
Anonymous
Post 01/25/2026 11:18     Subject: Blood type changed during pregnancy
Anonymous wrote:Someone made a mistake.

I've been telling people I'm O- for years, because that is what I was told and that is what my donor card said. When I gave blood a year or so ago, after not having given it for years, they gave me a new card. It says A-.

Mine didn't change. The O- was wrong.

How did you know that the O- was wrong rather than the A-?
Anonymous
Post 01/25/2026 11:14     Subject: Blood type changed during pregnancy
My mother-in-law swears up and down that her Rh factor changed from negative to positive after she received the RhoGAM injections. According to her, she went from O- to O+. I say this cautiously because the woman is a little bit nutty.
Anonymous
Post 01/25/2026 11:08     Subject: Blood type changed during pregnancy
Someone made a mistake.

I've been telling people I'm O- for years, because that is what I was told and that is what my donor card said. When I gave blood a year or so ago, after not having given it for years, they gave me a new card. It says A-.

Mine didn't change. The O- was wrong.
Anonymous
Post 01/25/2026 11:04     Subject: Blood type changed during pregnancy
My sister’s type was misidentified before she delivered her first baby. My mother noticed (from the wristband, maybe?), and her will of steel convinced the hospital to retest.
Anonymous
Post 01/25/2026 10:57     Subject: Blood type changed during pregnancy
Anonymous wrote:When I was pregnant, the doctor inputted the incorrect blood type. I pointed it out and she switched it back to O+. She also gave me the wrong meds right before delivery. I was very high risk and it could have gone badly.

She was useless.

Unfortunately I think most doctors are useless.

Not useless, no, but anything that involves data entry can be subject to human error by a doctor or a phlebotomist or whatever. Someone once inputted my blood type incorrectly (ex: O+ when I am O-) but I caught it because I know what my blood type is.
Anonymous
Post 01/25/2026 10:53     Subject: Blood type changed during pregnancy
Anonymous wrote:They made a mistake. Have them redo the blood draw. If they give you any grief about admitting the mistake, I would change practices.


Someone somewhere along the line made a mistake. And just FYI--your curiosity has been "piqued" not "peaked" (two words that sound the same but different spellings).