In 1937, Karl Landsteiner and Alexander Weiner discovered a new blood type: the rhesus blood type, or Rh factor. The rhesus protein is named for the rhesus monkey, which also carries the gene, and is a protein that lives on the surface of the red blood cells. This protein is also often called the D antigen. When it comes to blood transfusion, anyone who is Rh positive can receive blood from someone who is Rh negative, but those with negative blood types cannot receive from anyone with a positive blood type.
To put it simply, Landsteiner and Weiner discovered that blood types can be either Rh positive or Rh negative, doubling the commonly known blood types from four (A, B, AB, and O), to the eight we know today.
However, when it comes to the Rh blood types, many of us do not fully understand what it means to be positive or negative. In the United States, approximately 85% of the population has an Rh-positive blood type, leaving only 15% with Rh negative. Just as we inherit our blood type “letter” from our parents, we inherit the Rh factor from them as well. Each person has two Rh factors in their genetics, one from each parent. The only way for someone to have a negative blood type is for both parents to have at least one negative factor. For example, if someone’s Rh factors are both positive, it is not possible for his or her child to have a negative blood type. Only people with at least one Rh-negative factors will have a negative blood type, which is why the occurrence of Rh-negative blood is less common than Rh-positive blood.
When Landsteiner and Weiner discovered the Rh protein, they were researching solutions for the cause of a medical mystery that killed dozens of babies each day. This led to the development and FDA-approval of RhoGAM® in 1968. RhoGAM, or Rho(d) Immune Globulin Human, is a sterilized solution made from human blood. It is used to prevent an immune response in mothers who are Rh negative. If a pregnant woman who is Rh negative does not receive RhoGAM, and is carrying an Rh-positive baby, she risks the health of future pregnancies because she has been exposed to the positive blood from her current unborn baby.
Once a woman finds out she is pregnant, her doctor will test her blood to determine her Rh factor. Since more people are Rh positive than Rh negative, it is likely that an Rh-negative mother could be carrying a baby who is Rh positive, creating the risk for hemolytic disease of a newborn (HDN) in future pregnancies, essentially destroying that baby’s red blood cells. If a woman is Rh negative, she will most likely receive a RhoGAM injection.
When a woman receives RhoGAM, it protects her immune system from the exposure to the current baby’s Rh-positive blood. If she does not receive the injection, her body will develop antibodies that could attack the positive red blood cells of babies in subsequent pregnancies, which will cause HDN. HDN can cause serious illnesses, brain damage or even death in a fetus or newborn. Pregnant women typically receive RhoGAM twice during their pregnancy: once at approximately 28 weeks and once within 72 hours of delivery, if in fact, the newborn baby is Rh positive.
Although we have become accustomed to adding a positive or negative description to our blood type, the Rh factor plays a larger role than many of us realize. Knowing your blood type can play a significant role in your life and health.
Keep this going please, great job!
I am RH negative, unfortunately I found out the hard way after 2 miscarriages,my Dr’s could not pinpoint the problem. While in the ER with my second miscarriage they found out about me having the RH negative factor. I now have 2 beautiful children,but I wished they would have found it sooner. This article is very informative and really gives great insight on the Rh factors.Thank you,Paty
Thanks for the marvelous posting! I quite enjoyed reading it, you may be a fantastic author. That is an extremely smartly written article. Keep this going please, great job!
Thank you so much, Kenneth!
I too am a part of the RH Negative family. I loved reading this article!! I remember the first time my dr spoke to me regarding my blood type, he said, you know you’re among the special humans. I lol and asked was that a joke because throughout my adult life I had been told I had to be ever so careful due to the small percentage of RH Neg, people out there. I was even told it was smart to store my own blood whenever I knew I would have surgery. My mom, her mom/sisters all are Rh Neg. I was given the RhoGAM injections with all 3 pregnancies. None of my children have my blood type….So tell me again how special Rh Negative people we are, lol. Great read!
Hi Saun. You are special! Thanks for reading and supporting our mission.
I have a question… I know I’m rh negative and A does that mean I’m A positive with rh negative or A negative with eh negative… Just want to clarify it.
Dana, that means you are A-. The Rh is usually stated such as “Blood group A Rh positive” or “Blood group A Rh negative.” The RH is the factor at the end of their blood type.
I would like to know what happens when u inject rhogam into a rh – mother who’s carrying an rh- fetus ?? They never talk about this they just assume the fetus is most likely positive they never talk about the risk of injecting pooled blood from rh positive persons into a mother and child whom are both negative !! The risk of getting this injection and not knowing the child your carryings blood type just assuming seems naive and very dangerous!! Just sayin Rhogam can be a good thing but also very bad good forbid u get your rhogam at your 28 week visit when u are not carrying a rh positive child and u get into a car accident and u have rh positive running though your body for 3 weeks that doesn’t belong there you are putting both of u in danger ! What they don’t tell u is that the safest way is to wait till after u give birth to get rhogam after u find out babies blood type cuz the chances of blood mixing is so slim unless u have been in car accident had an amino or anything that could possibly mix yours and child’s blood which then u would have 72 hours to receive rhogam !
Hi Cindy. It would definitely be best to talk to your OBGYN or primary care physician about any issues pertaining to a pregnancy to ensure you have all of the knowledge before making any big decisions.
I am in this group also, I’ve lost 3 babies, but I got my miricale and rainbow baby boy, he’s 4 years old now, I’m so thankful my doctor caught it before, I went farther along in my pregnancy.
Stephanie, thank you for sharing your story! We’re so happy to hear about your healthy 4-year old baby boy.
My wife is rh positive. Now she is pregnant. In the past she had apportion. She did not injected the injection. The doctor said her bod may or may not prepared antibody.she told her to back after 6 months to see what will happen. But am afraid what will happen to the baby and my wife. Is there any medical solution to check now?
Hi Essays, it would be best to check with your OBGYN on these questions.
Can I donate blood if I’m anemic?
Hi Gina. Thank you for your willingness to donate! Our donor advocates will have a few more questions for you regarding anemia if you don’t mind calling them at 1-888-480-8200. Thanks!
Both my parents have been tested and confirmed to be rh+ yet me and my sister are both rh- ; does this mean that both my parents have one rh- factor each ?
Hi Ethan. That is correct! The only way for someone to have a negative blood type is for both parents to have at least one negative factor each.
What if am Rh+ then terminate a pregnancy for a man that is Rh-, will it have any effect on child bearing in the future?
Hi Tonia. It would definitely be best to talk to your OBGYN or primary care physician about this.
Hi my gf is pregnant with our first child together. She has had a child before and this will be her second. She was also not aware of what blood type she is until her recent blood tests. She discovered is A- and was subsiquently told she will have to take at least three to four shots with RhoGAM before our baby boy is born.I am now concerned having read up about potential risks mentioned herewith especially the high HDN risk when the mother is pregnant with her second baby. What can one do to ensure that the baby and mother are not affected especially when we do not know the baby’s blood type. I am AB blood type and Rh+ and I dread potential dangers involved.
Sabelo, we’d recommend speaking to your OBGYN or primary care physician in regards to these questions to ensure you have all of the knowledge before making any big decisions.
I am rh negative. I have 2 children whom are not the same, thankful for the rhogam injections I was given so that my babies were born healthy.
Thanks for sharing, Renee! We are glad to hear that your babies were born healthy!
Way back in 1974 when my daughter was born, the Rhogam injection was still being understood. I received the injection within 72 hours of the birth of my daughter. Fast forward to 1977, I had a very early miscarriage. In fact, the doctor at the ER was not completely sure if what I brought into the ER was indeed a miscarried fetus. He sent it to Pathology for determination. While in route going home, that doctor telephoned me and left a message to call him when I got home (no cell phones back then! Ha!) I returned his call and he said I should come back in to the ER right away and get a Rhogam injection just in case I indeed had a miscarriage. He did not want to risk any more time if there was a delay in Pathology process in determining if it was a fetus. Although I am glad he was he was aware of this Rh negative issue, I never had any children after that possible miscarriage (my choice). Keep up the great work Carter BloodCare!
Thank you for the positive feedback. We are sorry to hear about what happened to you. Thank you for sharing your story and helping others.
I am A-, what does my future hold as far as child bearing is concerned? Does my blood group A- have an effect on my wife and children i hope to have in future?
Hi Ronnie, Thanks for reaching out. It depends on what blood type your wife is. The risk associated with the Rh- gene only pertains to if the mother has it or not. If your wife is Rh+ she should not be at risk. To be safe, make sure to talk with your wife’s OBGYN or primary care physician about any issues pertaining to a pregnancy.
So, my eldest son is 0-. I am A+. His father must then be 0- and I must carry a silent Rh- from my parents in order for him to be Rh-? We both carry one Rh- which would explain how he is 0-. Wondered for a long time how I could have produced 0-.
My parents had 4 children. Only one is RH negative. Why wouldn’t all the children be either RH negative or positive?
Not all siblings have the same blood type. Each person has two Rh factors in their genetics, one from each parent. The only way for someone to have a negative blood type is for both parents to have at least one negative factor. Only people with at least one Rh-negative factors will have a negative blood type, which is why the occurrence of Rh-negative blood is less common than Rh-positive blood.
I am rh d negative I v had abortion in d past without knowledge of all these so ruhgam was not given, what if i v develope d anti bodies is it possible to carry a healthy pregnancy? Secondly, if d mother is negative and father positive who as d higher percentage of passing same blood to child?
The blood that is passed to the child is determined by both parents. In regards to if your next pregnancy will be healthy, we recommend you talk with your OBGYN or primary care physician about your specific situation.
So what happens when a B neg. Person receives B Positive blood ?
Hi Paul, B+ blood can only be given to B+ and AB+ people. B- blood can be given to B-, B+, AB-, and AB+. We hope that helps!
My blood type is Rh- and I am been sensitized. The antibodies developed in my blood after a first pregnancy (though Rhogam had been given appropriately) and before a second pregnancy. The doctor suspects I had an early-term miscarriage between my two (nearly) full-term pregnancies. I was monitored each month during my second pregnancy, but no intervention was needed and my second daughter was born healthy and strong. I assume she has Rh- blood. My question: Can I be a blood donor? Or, might the presence of these antibodies be potentially problematic for a recipient of my blood?
Hi Sara! Thank you for wanting to donate! Our donor advocates will be able to talk with you about your specific situation and let you know if it is safe for you to donate. Please reach out to them at 1-888-480-8200. Thanks!
I had 4 healthy children and I am Rh- I received the injections each time and all my kids are +. My first was born in 1983 the last in 1993. I never knew that I couldn’t receive blood of a different type. Is this true?
Hi Tamara, You can only receive blood from other negative donors.
I am rh- I have the rhogam shot with all my pregnancies and all my kids are fine even to my little girl who also has my blood type. I am thankful for the articles on rh- blood it has helped me to understand more about my blood and just how much I really need to donate it which I am going to start doing and I will also encourage my daughter when she gets old enough to donate also.
Thank you, Becca! It is important to learn about the blood type you have. We truly appreciate you donating and encouraging your daughter to do so as well.
I have 0 positive blood.
I have a sister who is RH negative. Are we blood sisters?
Hi Pamela! Siblings can often times have different blood types. Thanks for asking.
Greetings. I am O RH + and my husband and I many years ago went through 10 years of infertility treatment including IVF. We were unsuccessful 100% of getting pregnant. We were both strong, athletic, healthy with no reason on my part to not get pregnant (other than an inverted womb) and his sperm count was over average. We adopted 2 beautiful children instead which is a God send, however, I wonder if it had anything to do with our blood types possibly being un compatible? Am I way off here or is this possible? Thank you!
There are always a lot of factors, so we couldn’t say for sure. However, congratulations on your adoptions and we appreciate you doing that! What a wonderful thing.
My husband is o-, I am o+RH-,
My daughter sais shinis o+ can that be correct if I am considered o-?
Each person has two Rh factors in their genetics, one from each parent. The only way for someone to have a negative blood type is for both parents to have at least one negative factor.
My name is Tracy and I am O-Rh-. I’ve been reading about rh- and O- blood types. Since I have the o negative and rh negative I was wondering if this type is more rare? Any feedback would be appreciated. I’m trying to get as much information on it as I can.
Thank you
Hi, Tracy — AB- is actually the most rare type of blood (~1% of the population has it). But only about 7% has O-, and it’s the universal donor!
Message*am now 28th week first pregnancy and am rh- ,and i was to. be given anti-d yesterday buh when i went to the hospital i was told that they dont have it,now am worried because i dont know what next,is there any risk for me and my baby?please tell me
Abigael – please consult your physician; and if your physician needs help, he/she can call our MD-on-call if they have questions about the testing.
Thank you for this article. My blood type is A- and I am Rh- as well. All 3 of my children have the same blood type. Does this mean that they may have the Rh negative trait as well
You’d want to get them tested, just in case, but there’s a chance, yes!
We’ll be able to tell them their blood type if they donate!
I am a rh b negative. I had only one shot with my first child in 82 but receive 2 with my second one at 6 mons and one after delivery. No problems with either. But my sister who is O positive I believe kept having miscarriages with one certain ex husband. Could he have been rh negative?? She has had 3 boys many years ago all in their 30’s. Also can a rh B negative like my self donate blood to an O negative person whom needs blood for transfusion and also if I have had active hepatitis along with the active antibodies due to hepatitis at age 15??? Can I still donate ???
We cannot comment on the first part of this as we don’t have any research on it.
However, you can check your eligibility here: http://www.carterbloodcare.org/eligibility/
I am o+ and rh+ and had several miscarriages my husband is rh- could this be why I am having the miscarriages
We cannot speak to that. We suggest you consult your OBGYN on this issue.
I did blood tests in 2013 that said I’m b+ never got any injection s with my second pregnancy I went into labour at 31 weeks and 4 days before my Emergency c section a blood test was done and I’m infact Rh negative. Baby keeps getting jaundice…. I did however receive the anti d injection after the birth. Why does my baby keeps getting jaundice? Breast milk perhaps? Please help I’m freaked out
Please consult a physician. Since we don’t know all the details, we are unable to give you council.
Hi, I’m AB- and my first 3 children are rh- and my youngest is the only one who is rh+ (all same father). Does this mean my husband has both +- traits? Also, would I be able to have one more baby without any complications?
Please consult a physician. We aren’t able to predict complications or give medical advice.
I am A- and married to a man who is O+, we have a child who is almost 5 years old. I was given the Rhogam shot within 48 hours of delivery. I would like to know if rhesus incompatibility affects the conception of future pregnancies. Thank you.
Please consult a physician. We aren’t able to predict complications or give medical advice.
I am B negative, my husband B positive. Both of our children are RH positive. With both children I developed Hellp Syndrome (severe pre-eclampsia) at 37 and 36 weeks respectively. With my first child I was induced, the second was an emergency c-section. They were born 8 years apart and since Hellp is rare, during my second pregnancy I was told the chance of getting Hellp again was slim. I had no trouble conceiving and am otherwise healthy, and my pregnancies were normal up to that point. I always felt my Rh negative status was a factor.
Perhaps so. However, we aren’t able to predict complications or give medical advice, so please consult a physician if you have questions about your pregnancies.