Rh factor

Rh factor is also called "Rhesus factor" because it was first discovered in the blood of Rhesus monkeys (small monkeys from India often used for experimentation). Rh factor is an antigen, a substance which stimulates the production of antibodies to fight foreign invaders, such as viruses, bacteria and transplanted organs. A given individual either has the antigen already in their blood (they are Rh positive), or they don't (they are Rh negative). A patient's Rh status effects how he or she handles blood transfusions or organ transplants.


Prior to the twentieth century, blood and its function was poorly understood. In trying to solve the problem of serious blood loss from injuries, doctors tried to inject (transfuse) blood from another person or animal into the injured patient. In some cases, this worked and the patient recovered. In many more cases, however, the blood transfusion actually harmed the patient, often causing death. No one could predict which type of reaction would occur as a result of a blood transfusion. So, by the beginning of the nineteenth century, most European nations had outlawed the practice of blood transfusion.

About 1900 Austrian-American physician Karl Landsteiner (1868-1943) developed an explanation for the phenomenon of blood rejection. Landsteiner found that human blood serum (the liquid portion of blood surrounding the cells) could be divided into four categories, depending on its ability to cause clotting of red blood cells. He gave these groups the names A, B, AB, and 0 based on what type of clotting antigen they had, if any.

In 1940 Landsteiner discovered another of blood factor antigen, known as Rh. This discovery resulted from Landsteiner's studies with Rhesus monkeys. Landsteiner and his colleagues found that when blood from monkeys was injected into rabbits and guinea pigs, it clotted. This was because of the presence of another antigen that the researchers had not classified before. Landsteiner called this antigen the Rh (Rhesus) factor. Researchers also showed that the factor occurs among some, but not all, humans. It is also inherited.

Importance of Rh Factor

The Rh discovery had immediate practical importance because it explained a relatively common medical disorder known as erythroblastosis fetalis. In this condition, an Rh-negative woman who becomes pregnant with an Rh-positive fetus (an unborn child) sometimes develops anti-bodies against the Rh factor in the fetus. This development usually causes no problem during the woman's first pregnancy, since the number of anti-bodies produced tends to be small.

By the time a second pregnancy occurs, the situation has changed. The number of Rh antibodies produced by the mother's body has become large enough to cause destruction of red blood cells in the fetus. This can result in complications such as anemia (a chronic blood condition characterized by lack of energy), jaundice (a condition in which bile pigments build up in the blood and cause skin, eyeballs and urine to take on a sickly yellow tone) or premature birth. Today, this reaction can be controlled by immunizing Rh negative women after their first pregnancy with a drug known as RhoGam.

User Contributions:

synakk ak
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Jan 23, 2010 @ 1:13 pm
Wouid you please inform me that 2RH positive parents can produce a RH negative baby ?Because my blood group is b+ and my wifes blood group is o+.But my childs blood group is B negative.What are the reasons behind it?Iam tottally confused.So would you please send its answer to my e-mail id-? My adress is synakkak@gmail.com.
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Jun 12, 2010 @ 2:14 pm
Synnakk Ak: I think you can pass on the recessive gene for rhesus negative (weak rhesus negative), so one of you could have this. Or it could be that the results of your blood tests were wrong. I would either go to your doctor and get tested again, give blood and get tested there or buy a home test kit online and test your blood yourself.
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Feb 21, 2011 @ 11:11 am
the presence of the rhesus factor in offspring is determined by the presence of this factor in the parents genotype.one of the parents' genotype must either be homozygous or heterozygous positive of this trait.if both parent are homozygous of this trait,then all their offspring would be rhesus positive but if one of the parent is heterozygous,all their offspring would be rhesus positive but genotypically they would be homozygous and heterozygous in the ratio 1:1. this shows that the rhesus factor is a dominant trait in man.
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May 18, 2011 @ 12:12 pm
I was the first baby in the world to survive after a transfusion for the Rh factor. I'm trying to find a newspaper article from a Boston newspaper about my birth or my sister's birth, two years later. It would have been in 1945 or 1947.
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May 25, 2011 @ 6:06 am
How can a knowledge of Rh factor help one in the choice of choosing a marriage pattiner
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Jun 8, 2011 @ 5:17 pm
Pls does it mean that every Rh positive father can keep producing Rh positive child? And can this Rh factor be the reason why some couple after giving birth to their first child become unable to produce more children?
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Feb 7, 2012 @ 5:05 am
Rh negative mother and Rh negative father produced an Rh negative child. Mother required 2 units of blood to be transfused after the child's birth. Now the mother is pregnant with child 2. Midwife is recommending Rhlg injection at 28 and 32 weeks to protect the child because of the previous transfusion. Is this necessary or recommended when both parents are Rh neagtive?
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Mar 30, 2012 @ 2:14 pm
Question for anyone knowledgeable about the RH factor. It is a possiblity that since the RH factor was relatively misunderstood, or unknown prior to the 20th century, that it could impact one's family in the following way: My father is an only child, his father was an only child and his father was an only child. This represents roughly 86 years of only children in the family. Could it be that since the RH factor does not have a significant impact on the firtborn, but does on subsequent pregnancies, that the RH factor, or lack thereof, could have prevented subsequent children being successfully born into this family for three generations?
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Aug 12, 2012 @ 2:02 am
My brother John, born 3/19/42 in San Francisco, CA @ U.C. Hospital on Parnasus Ave. was the first blue baby born that survived when a new wonder drug had been created but not used on a human yet. My mother was told that he would die but would have a 50/50 chance if she would agree to having a transfusion with this new wonder drug. He did survive & was told that they used this drug on all RH factor babies born after him. If there is a newspaper article on this, I would sure like to see it.
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Aug 17, 2012 @ 3:15 pm
Im 22 weeks pregnant and only found out that im RH negative,this is my fourth pregnancy but i have had two miscarages after my 13 year old child and never got the rhogam shots.Can my situation be controlled now?im stressing and scared.
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Nov 10, 2012 @ 5:05 am
I was born in Oct. 1945 and the product of RH factor parents. I was told later that I was one of the first in the US to have been totally transfused at birth. My parents had a son 2 years earlier who only lived 3 days. There was an article in the Seattle Times when I turned 2 years old which stated that my transfusions at birth had changed some of the ways the Seattle Blood did their business, but am unaware what those procudures entailed. I had total transfusions at birth and then about 2 months later was taken to Seattle Childrens Hospital for more transfusions. There appears to be no circumstantial problems after that physically. I do tend to become anemic, but I weigh about 102 pounds and that is probably a contributing factor more than the birth situation. I had no problems in 1968 or 1974 when I had my two sons. I did have substanial bleeding and actually died after the birth of my first son, however, was told this was an anomaly rather than RH. I was not told of my RH factor problems until well after the birth of my sons. To anyone who does have this problem, I would suggest speaking to a blood bank or contacting a University who can probably explain it if your doctor cannot answer you properly ( and then I would change doctors). Best wishes.
Jeanine jones
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Nov 11, 2012 @ 8:20 pm
If a mothers O positive and dads Apositive can they have a baby the O negative with the rh factor. Does one have to have the rh factor in order to have an rh factor child?
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Nov 17, 2012 @ 7:07 am
yup they have a baby with o negative blood group when mother and father both are hetrozygous for O positive and A positive and certainly hetrozygous for Rh factor.there are 25% chances of this type of gametes.
Bhags Khetwal
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Jan 20, 2014 @ 9:21 pm
Thank you for giving a right knowladge about
Rh factor but you have to give diagram also
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Sep 10, 2014 @ 11:11 am
my mother told me that I was the first baby to be trasfused at Beth Israel Hospital in NYC in 1947.
A brother with the Rh factor died 10 mos. earlier
antony mbogo
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Oct 9, 2014 @ 10:10 am
thanks a lot for the info since it is transforming many particularly to me in the case of my study,GOD bless
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Dec 1, 2014 @ 3:03 am
Okay i need help understanding i am not sure of mine or my parents blood types i do know my sister is o begative with rh negative does this mean i too will be rh negative.? My next question is i have been cleared from a dr saying i have no fertility issues as has my husband but in 8 years were not parents yet is it possible that our blood types could be not compativ
ble causeing us not to be able to get pregnant?
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Dec 14, 2014 @ 9:09 am
I am B Negative yet both of my parents are positive, apparently it can be passed down from their parents. I think my Grandma on my mums side was also B Negative. She had 10 children with no trouble, long before the AntiD injection existed so I wouldn't worry to much about pregnancy. I had my son who is B Positive with no complications and had 2 injections of AntiD before and after he was born and he's very healthy. Also forgot to mention my brother is Positive so siblings will not always be the same.
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Mar 30, 2015 @ 8:20 pm
I am A- and my sister is O- WHILE my dad is A+, and my mom could be RH+ because RH negative is THE recessive gene (=the weaker gene that needs 2 copies of the gene to become the dominant gene >> while it actually just leaves no space for a dominant RH+ gene :-P ). So in the case of the worried dad, God made you pass on the RH- gene as did your wife. Nothing went wrong. And the 2 RH- parents would not need the RHo shot but they kinda force it on you today as an RH- woman so that you don't make antibodies to the RH+ blood. P.S. It seems some rabbits also have Rh- blood.
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May 12, 2015 @ 2:14 pm
My brother was born in early 1947 and had a blood problem. My mother was A- and my father was O+. Dr enneth Lemon of Oskaloosa,Iowa had just returned from overseas after taking instruction at London's largest obstetrical hospital where the transfusion were being given by whole blood into the carotid artery. He treated my brother by using the femoral artery and using blood plasma. My olderand his borother in law Dick burned up the engine in a brand new Pontiac getting the plasma from Iowa City. We were told that he was the first baby in the US to have this plasma treatment done and survive.
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Jul 2, 2015 @ 5:05 am
My wife blood group is o+ and my group is a- is there any problem in baby if my wife pregnant.
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Jul 7, 2015 @ 11:23 pm
I wlss saved by a blood transfusion as a infant, mother wss RH neg. I have posotive blood now. This wad in the 50s,how many us are alive today due to at birth with them as i had? Is tjis rare ? How many of us survived?
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Jul 12, 2015 @ 5:17 pm
I was born in the 50's also and had several blood transfusions. My parents told me I almost died. I wonder if there were ever any studies done to see how the RH factor has affected the babies who were treated with blood transfusions and survived. I've often had troubles with anemia and have taken iron supplements for years.
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Sep 6, 2015 @ 1:01 am
I was born in 1954, 2 months premature with AB - blood. In order to save my life I had a complete transfusion to change the RH factor to positive. Although I was very pale from childhood on into my 40's, I didn't experience anemia until my 4 pregnancies so,iron supplements were essential. Other than that, I've been pretty healthy.
Patricia O'Neal
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Sep 10, 2015 @ 9:09 am
My father was RH positive. My mother was O-. They had 13 children. The third birth was a blue baby. She died. The 11th and 13th babies were also blue babies. I am O-, as were other siblings. After their first birth, what would be the percentages that the other babies should/would have been born blue babies?
When I was pregnant with my first child, my doctor told me to have my husband come in for his blood type. I told the doctor my husband was also O-. He said there would be no problems with the birth of our children. My daughter is also O-. Is this common?
Sally Bartlett
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Oct 24, 2015 @ 10:10 am
I am a writer and just very interested in different health subjects and the RH factor is one of them. Both my parents are dead, so I am not sure which had the negative, but I suspect my mother. I am A positive, as are my children. I do not know the blood type of my brother either who is 7 years older than me but will ask next time I talk.

Here is Mom's history with pregnancies: induced abortion at very young teen age in late 1920s; first baby, second pregnancy born in 1934 with husband number 1; third pregnancy (ME) born 1941 healthy, extremely fast birth; fourth pregnancy but second with my father, 1943 who died in utero at around 28 weeks.

Now I understand that if mom is RH neg and has an RH pos baby that the next pregnancy may have problems, which could have been my brother (after the abortion) me (after my brother) or the baby that died (after me). Since there were 3 fathers involved I am trying to figure out what happened. My best guess and let me know if this seems correct is that my Mom was RH neg and apparently so were first 2 fathers. (and also my brother?) MY dad was RH pos and my birth created antibodies in my mother that led to the next baby's death.

Second question: if my DAD was negative, could that have affected the pregnancy? Seems only the mother's negativity seems to be problematic.

Thanks, Sally
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Mar 20, 2016 @ 4:16 pm
We all have 2 alleles for blood group and rhesus factor. O is recessive (not as strong) so to be blood group O you have 2 O alleles. The rhesus factor for -ve is also recessive, so to be Rhesus -ve you'd get a -ve from both of your parents. This can still happen if both if your parents are +ve because the +ve overrides the -ve so they can have a +- and be +ve themselves but both give you their -. I am O+, so all I can give to my children is the O allele, which isn't as strong as A or B, meaning I have 2 O alleles, so can only give my chilren an O. My husband is AB+ve, all dominant alleles. We have 5 children, all of whom will be either A or B but all of whom could still be Rhesus -ve. We know one of our sons is A+ve and another is B+ve, so it all works! They are either Ao or Bo as they will only get a recessive o from me but will get a dominant A or B from their dad, but if we are both Rhesus +- we could both have given the -ve to our children. 4 possible outcomes for our children: Ao +ve (A pos) Ao -ve (A neg) Bo +ve (B pos) Bo -ve (B neg) I love genetics!
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Jul 23, 2016 @ 1:13 pm
I was born a twin in 1949 but my brother only lived 3 days. My mother was RH- andI am RH+. We were her 5th pregnancy. Her first two births were fine. Her third baby did not live and her 4th baby, in 1948, was given blood to save his life but has cerebral palsey. I feel incredibly lucky to be alive since my blood type is RH+ and hers was RH-. My twin brother was born first and I don't know if that had an effect on the outcome. My mother went on to give birth to 5 more babies. Two died and the other three has succesful blood transfusions. On a sis note, my birthday is tomorrow and I always think of my twin very profoundly as the day of our birth nears.
Bree Fryar
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Nov 20, 2016 @ 9:09 am
Mother born in 1918 was Rh-, Father must have been Rh+ because they lost many children before me. Mothers first child by another man was fine. Never heard anything about this until I got pregnant in 1967. My son was given a transfusion at birth. I am O- and my husband was O+. The question is : why is my son's blood A+? My first child ( blood type in question) was a twin. His twin never formed but I delivered what looked like a kidney. My second child was fine after being given the shot. She also was a twin. I delivered her twin 2-3 weeks after her birth. It just fell out while standing taking care of her. The hospital verified that it was an undeveloped fetus. She has O+ like her father. Both children are from the same Father, but 1st son has the A+. Was I given the wrong baby? This was questioned at his birth but the doctor just more or less ignored me. I've tried for years to find this answer. Please help.
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Nov 29, 2016 @ 4:04 am
I was born on 17th April 1942. I was the 2nd child of an RH- mother and RH+ father. When I was 6 weeks old, I was taken to the hospital where the blood was drained from my ankle and my aunt's blood transfused into me via my arm. I still have the scars. I was lucky as she happened to have RH+ A type blood and it saved me. By the time my brother was born in December 1943, they were ready to take him straight t the Children's Hospital for transfusion. I was told I was the first baby born in NSW with this issue to survive. I am now 74 and delighted to be around. There are no such issues within my family these days. How lucky for me.
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Jan 19, 2017 @ 11:23 pm
I've seen a chart online that tells you what blood types together will produce in your child if this is any help to anyone. I can not remember exactly where I seen it but I'm sure it shouldn't be too hard to find.
Patricia Kolpin
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Dec 11, 2017 @ 9:09 am
My son was transfused twice when an infant and could this have anything to do w/ the kidney failure he is experiencing?
Janet Meehan
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Dec 23, 2017 @ 10:22 pm
I believe the first baby to survive in the US was Janice Wylie in 1942. She was born in Evanston Hospital outside of Chicago. She had 7 transfusions into her buttocks in 10 days time. "Her little back became tattooed with Vitamin K shots." Pediatricians from Wisconsin and Northern Illinois came to look at her. Her father, Max Wylie wrote the book "The Gift of Janice." A heartbreaker of a book that may be out of print.
In California, Patty Meehan was supposedly the 2nd RH baby to have survived this. She has lived a charmed life & is a retired teacher from Merced, California. Patty was born in 1951.
Richard Adkins
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Feb 10, 2018 @ 10:22 pm
It is possible to have an Rh- and an Rh+ set of parents and get an Rh- child. My mother was O+ and my father AB-. My mother had been married previously to my dad, but her first husband was also Rh-. My mother's first child was delivered without problems. Her second child, with a different, but also Rh- husband was born with serious health issues in Jan. 1943. Subsequent children were born in 1946 (with an Rh problem solved by transfusion), 1947 without complications, and me in 1948 requiring a transfusion. My parents divorced and in his subsequent marriages, he continued to have AB- children. It is my understanding that with my parents' blood types, the chance of an AB child was 10% and that the chance of a AB- child was 1%. As an AB- mother, my sister and her RH+ husband also had three AB- children.
Carrier D Cooper
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Mar 12, 2018 @ 8:20 pm
What happens when RhD is not present to remove ammonium from a cell? What happens to the ph level? What happens when toxins are not removed, from rh- red blood cells?

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