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Rhesus (Rh) Factor Easily Explained

Updated on July 20, 2013

When the nurse arrived in my hospital room shortly after the birth of my first child to administer a Rhogam shot, I knew very little about the Rhesus (Rh) Factor. Over time and the birth of three more children, I would learn and feel very grateful to three doctors named Wiener, Landsteiner and Levine.

Blood types.
Blood types. | Source


Humans have four different blood types, A, B, AB and O. According to, the site I found with the easiest explanation, "Each of the four blood types is additionally classified according to the presence of another protein on the surface of RBCs that indicates the Rh factor. If you carry this protein, you are Rh positive. If you don't carry the protein, you are Rh negative."

Only about 15% of the population is Rh negative. This only becomes a problem when an Rh negative woman conceives a baby with an Rh positive man. It's about 50/50 whether the baby will also be Rh negative.

"Rh incompatibility usually isn't a problem," the Kidshealth article says, "if it's the mother's first pregnancy because, unless there's some sort of abnormality, the fetus's blood does not normally enter the mother's circulatory system during the course of the pregnancy." The problem arises when the mother has other pregnancies following her first child. Even if the baby is Rh positive and not Rh negative, the mother's Rh antibodies will see the baby's blood cells as unfamilar and begin to attack them. The baby's blood count can then become dangerously low - the condition is known as hemolytic or Rh disease.

So to summarize, your first baby is fine, but during delivery, the blood of the fetus enters the mother's blood stream producing antibodies putting the 2nd, 3rd and further babies at great risk of attack by these antibodies. In times past, I was told my 2nd, 3rd and 4th children would have been very sick and probably even died. Often the ill child was transfused, but today we have Rhogam and it has reduced the need for transfusions, says Kidshealth, " fewer than 1%."


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The Rh factor or Rhesus Factor was named for the Rhesus monkey in which it was first discovered. Three men were significant in bringing this factor to light. The New York Times first mentioned the Rh Factor in 1944 and according to Nicholas Bakalar, "The article quoted Dr. Alexander S. Wiener, who in 1940, along with his colleague Karl Landsteiner, first described the Rh factor in humans." But it wasn't until 1947 that Dr. Philip Levine mentioned a possible treatment for the blood disease trait. And in 1965, Bakalar goes on to say, "...the first clinical trials of a drug where under way."

According to, the discovery of the Rh factor, "... resulted from Landsteiner's studies with Rhesus monkeys." Researchers also showed that the factor occurs among some, but not all, humans and is inherited.

The drug, Rhogam, according to the product site, "...has protected millions of mothers." The site goes on to say that the drug is still the leading, "immune globulin brand for the prevention of Rh hemolytic disease of the fetus and newborn (HDFN)." Before the drug, HDFN was the leading cause of infant mortality and was responsible for, " average of 10,000 deaths annually in the United States."

Some pretty disheartening figures if you were living before the drug was invented.

Four healthy daughters may not have been possible for the author had she birthed them before the 1965.
Four healthy daughters may not have been possible for the author had she birthed them before the 1965. | Source


But with today's marvelous modern medicine and the hard work and research of doctors Wiener, Landsteiner and Levine, Rh negative mothers are able to birth healthy, multiple children without fear that her own blood may start attacking her babies.

For that we thank these fine professionals and, of course ... the rhesus monkey.

ADDENDUM: Weird Beliefs Have Surfaced About Rh Negative People

The Web is riddled with a theory on the origin of the Rh Factor that strikes as bizarre. The site, asks the question, "Where did the Rh negative come from?" It then posts this familiar information that is found on many sites that question the origin of the Rh Factor, "Northern Spain and Southern France is where you can find some of the highest concentration of the Rh negative factor in the Basque people. Another original group were the Eastern/Oriental Jews. In general, about 40 – 45% of Europeans have the Rh negative group. Only about 3% of African descendent and about 1% of Asian or Native American descendent has the Rh negative group."

The strangest claim on these sites is this list of characteristics that are repeated over and over on the web:

People with Rh negative blood group have certain characteristics that seem to be common among the majority. Here is a brief list of the most common.

¨ Extra vertebra.
¨ Higher than average IQ
¨ More sensitive vision and other senses.
¨ Lower body temperature
¨ Higher blood pressure
¨ Increased occurrence of psychic/intuitive abilities
¨ Predominantly blue, green, or Hazel eyes
¨ Red or reddish hair
¨ Has increased sensitivity to heat and sunlight
¨ Cannot be cloned
¨ Alien Abduction and other unexplained phenomenon

The final claim is that Rh Negative people are the offspring of aliens or the sons of gods (Nephilim). There are even those who claim Rh Negative individuals are reptilian humanoids.

Author's note: I may have blue eyes and light hair, but I'm not sure I can be cloned and I certainly haven't been abducted by aliens, but I do like the idea that I might be some sort of "angelic being". I'm sure my children would beg to differ at times. Sigh! I guess every mystery gives way to multiple strange explanations.


Bakalar, N. (2011, January 3). First Mention - Rh Factor, 1944 - The New York Times - Breaking News, World News & Multimedia. Retrieved July 20, 2013, from

Dowshen, S. (n.d.). Rh Incompatibility . KidsHealth - the Web's most visited site about children's health. Retrieved July 20, 2013, from

Rh Factor - used, first, blood, body, produced, function, history, History, Importance of Rh Factor. (n.d.). Medical Discoveries. Retrieved July 20, 2013, from


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    • carlajbehr profile image

      Carla J Behr 2 years ago from NW PA

      I was given the shot after my first child in the hospital and every child thereafter.

    • profile image

      Lici Murniati 2 years ago

      I'm Rh negative and never had rhogam for my pregancy

    • carlajbehr profile image

      Carla J Behr 3 years ago from NW PA

      I cannot substantiate the validity of these answers, but they seem pretty consistent:

    • profile image

      Arpita 3 years ago

      Is there a O RH positive blood group?

    • carlajbehr profile image

      Carla J Behr 4 years ago from NW PA

      Thanks Teaches!

    • teaches12345 profile image

      Dianna Mendez 4 years ago

      Interesting post, Carla. I am not RH negative, but it is good to know the history and symptoms. You certainl have done a great job in reserching this topic and people will find it helpful. Voted up.

    • carlajbehr profile image

      Carla J Behr 4 years ago from NW PA

      That's the way I read it - ha ha

    • Sue Bailey profile image

      Susan Bailey 4 years ago from South Yorkshire, UK

      Thanks for the link. I was panicking slightly and wondering if I'd been unfaithful whilst in a trance or something Lol! So two positives CAN make a negative!

    • carlajbehr profile image

      Carla J Behr 4 years ago from NW PA

      The answer at this link might help:

      Thanks for sharing.

    • Sue Bailey profile image

      Susan Bailey 4 years ago from South Yorkshire, UK

      I am type A Rh positive. My daughter insists she is O Rh negative. I'm not convinced since her father is O Rh positive. Can two positives make a negative?

    • carlajbehr profile image

      Carla J Behr 4 years ago from NW PA

      Thank you all for reading and also sharing your thoughtful comments.

    • Jackie Lynnley profile image

      Jackie Lynnley 4 years ago from The Beautiful South

      This is so interesting. I have this and had the shot after my first baby to protect my 2nd but both of my babies had the RH neg just like me so there would have been no danger. My mother also had this and all my siblings.

    • btrbell profile image

      Randi Benlulu 4 years ago from Mesa, AZ

      Thank you for explaining this so clearly. I have been aware of RH Factor for many years. I also know of the treatment but I don't think I ever really knew how it was caused. Thank you for enlightening us! You have 4 beautiful daughters, and while they may not always think you of you as an

      "angelic being", they really know you are! Up+

    • profile image

      MysticMoonlight 4 years ago

      Interesting Hub. I am Rh negative and received the Rhogam shots after the births of my children as well, and, like you, I'm very grateful to those that made this possible. I actually know a woman (a friend's mother) that is Rh negative and after having her daughter (my friend) had several miscarriages later in life due to the Rh factor incompatibility, they believe. My friend's mother was always very sad about not being able to have more children but after 4 miscarriages, she was afraid to keep trying. It was very tough for her and knowing this, it really puts emphasis on how lucky we all are today!

      I, too, have heard the extraordinary tales and weird claims about Rh negative people! Who knows, huh? I do fit into almost every category except for the cloned thing, not sure there, of course, and I don't remember ever being abducted, but then, would I? LOL :) Anywho, great article! :)

    • WVitanyi profile image

      WVitanyi 4 years ago from Edinboro, Pennsylvania

      Good hub, Carla. However, everyone knows that aliens erase your memory after an abduction, leaving only residual imagery.

      Keep up the good work!