Rhesus Factor And Pregnancy: A Must Read If You Have Rh- Blood

Rhesus Factor And Pregnancy: A Must Read If You Have Rh- Blood

Rhesus Factor And Pregnancy

Human blood is grouped into four types: A, B, AB, or O. Each letter refers to a type of antigen found on the surface of red blood cells. For example, Type A blood has antigens known as A-antigens. Each blood type is also grouped by its Rhesus factor (Rh).

Rhesus is another type of antigen on the surface of red blood cells.

Blood is either Rh positive (Rh+) or Rh negative (Rh-).

Most people who have the Rhesus factor are Rh positive and those who don’t have the Rhesus factor are Rh negative.

How Do I Know My Blood Type?

If you don’t know your blood type you can ask your care provider to refer you for a blood typing test. Globally, the most common blood types are O+ and A+. Approximately 85% of the population has the Rh factor and the remaining 15% is Rh negative.

The Rh factor is passed down from parents’ genes to their children. If a mother is Rh negative and the father is Rh positive, their baby can inherit the Rh gene from the father and be either Rh positive or Rh negative. The Rh positive gene tends to be stronger and will take over, even when paired with a Rh negative gene. So if the mother is Rh negative and the father is Rh positive, the baby is likely to be Rh positive. If the mother and father are both Rh negative, the baby will also be Rh negative.

How Can The Rhesus Factor / A Negative Blood Group Be A Problem?

Problems with the Rhesus factor occur when the mother’s Rh factor is negative and the baby’s Rh factor is positive. This is called Rh incompatibility. These problems usually don’t occur in first pregnancies but will arise in subsequent pregnancies.

If the baby’s Rh positive blood manages to mix with the mother’s Rh negative blood during pregnancy or labour, the mother’s blood will create antibodies against the Rh factor, as though it were a harmful substance. This means the mother becomes ‘Rh sensitised’.

The Rh antibodies can cross the placenta and attack the baby’s blood, destroying the red blood cells. This causes hemolytic anaemia, which is when the red blood cells are destroyed faster than they can be replaced. If this occurs, bilirubin (a by-product of red blood cell breakdown) builds up in the baby’s bloodstream. After birth, the baby can appear lethargic, have low muscle tone, and yellowing of skin and eyes (jaundice).

Red blood cells carry oxygen to all parts of the body. If there aren’t enough red blood cells, the baby might not receive enough oxygen. Fetal hemolytic anemia can lead to serious illness and potentially death.

How Does Rh Sensitising Happen During Pregnancy

During pregnancy, the mother’s and baby’s blood systems are separate. However, during pregnancy, labour or birth, a small number of red blood cells from the baby can cross the placenta and enter the mother’s blood. This can also happen if the mother experiences:

  • Amniocentesis (sampling of amniotic fluid via a needle inserted through the abdomen)
  • Chorionic villus sampling (sample from the placenta via needle inserted into the abdomen or through the cervix)
  • Any bleeding during pregnancy
  • Any blunt trauma to the abdomen during pregnancy
  • A pregnancy that ends in miscarriage, termination or is ectopic (implanted in the fallopian tube instead of the uterus), or
  • If baby is breech and manual rotation is attempted before labour

This Is My First Pregnancy With Rh Factor – Are There Any Concerns?

In most situations it takes time for a woman’s body to produce antibodies once sensitisation has occurred. This means in the first pregnancy with an Rh positive baby there are rarely serious problems, as the baby is born before many antibodies are developed.

However, during the first pregnancy with Rh factor, it is necessary for a mother to have treatment, if she intends to have more children. Any future pregnancies with a Rh positive baby are at risk, if the mother’s antibodies cross the placenta and attack the baby’s blood cells.

How Can This Be Prevented?

Nothing can be done about the Rhesus factor of your blood, or your partner’s. If your blood test comes back with a Rh negative result, your care provider will request that your partner’s blood type be tested. If your partner is also Rh negative, there’s nothing to be concerned about. If your partner’s results are Rh positive, further testing might be needed.

Your care provider can organise several blood tests during your pregnancy, to monitor the antibody levels in your blood. After birth, your baby’s blood will be tested for its type. If your baby has Rh positive blood, you will be offered an Anti-D injection within a few days of the birth. This will prevent antibodies from forming in your bloodstream. When given to a non-sensitised Rh negative person, the Anti-D targets any Rh positive cells in the bloodstream and prevents the production of Rh antibodies. Anti-D isn’t useful if you have already become Rh sensitised.

If you experience any bleeding during pregnancy, or if you have an amniocentesis, miscarriage, ectopic pregnancy or termination, make sure your care provider is aware as soon as possible. All of these might present opportunities for the blood of the fetus to mix with yours, and it will be unclear in most of those cases as to which blood type the baby has.

Some care providers recommend giving Rh negative women Anti-D injections without doing blood tests to detect antibodies. This might prevent antibodies from forming but it’s not without risks. The Anti-D is a blood product (which has its own risks), and in rare cases can cause allergic reactions.

If your pregnancy is normal and healthy you might opt not to have Anti-D injections until after the birth, when your baby’s Rh factor is known. The chances of blood mixing in a normal, healthy pregnancy are very slim, and if your blood tests show no antibodies present, you might prefer to find out whether it’s necessary before having the injections.

I Have Already Formed Antibodies Against The Rhesus Factor

If your blood has already formed antibodies you’ll need to be closely monitored for any signs your baby is anaemic. If your baby has mild anaemia and it’s safe to do so, your baby should be able to go full term. If the anaemia is severe, your baby might need to be born early or, in rare cases, be given a blood transfusion through the umbilical cord while still in your uterus.

If Rh incompatibility occurs, specialist care your baby might require after birth includes:

  • Blood transfusions
  • Hydrating fluids
  • Electrolytes to regulate metabolism
  • Phototherapy

The risk of antibodies forming exists with every pregnancy, even if you have been given the Anti-D injection in your previous pregnancy. It’s important to make sure, with any future pregnancies, that your blood group is known to all care providers you deal with. Being informed and aware of your blood group will give you peace of mind, and help you make the best choices for you and your baby.

Recommended Reading: Jaundice In Newborns – The Truth About Jaundice.

Also see: “Anti-D in Midwifery: Panacea or Paradox,” by Sara Wickham

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Sam McCulloch enjoyed talking so much about birth she decided to become a birth educator and doula, supporting parents in making informed choices about their birth experience. In her spare time she writes novels. She is mother to three beautiful little humans.


  1. my comment is a question, and it goes like this, 12years ago I terminated a pregnancy and I am o rhesus(-). just until recently I read about negative rhesus factor in pregnant women and how it affects the un born baby. I just got married recently and believing God to be pregnant. am I at risk because I did not take that medicine to prevent the anti bodies from forming in my blood then because of my ignorance. what do you advice me pls?

    1. Lorretta I urge you to find out the blood group and rhesus factor of the man who impregnated you 12 years ago. You can only be at risk if he happens to be a rhesus positive. If he is rhesus negative you need not to worry .

    2. I also terminated pregnancy 4yrs back..n the pregnancy was 4months…am married n I need I child. I did not get the Ant D…please help

  2. If am O-can my baby be O-and will I have a safe birth because my husband is O+ but have terminated a pregnancy before

    1. Your baby could be O negative or O positive. I am O negative and I had a miscarriage before my daughter and didn’t receive anti D injections I didn’t even know my blood type but I did go on to have a successful second pregnancy my daughter is now 3 and has positive blood.

  3. If am O-can my baby be O-and will I have a safe birth because my husband is O+ but have terminated a pregnancy before.

    1. Your baby could be O negative or O positive. I am O negative and I had a miscarriage before my daughter and didn’t receive anti D injections I didn’t even know my blood type but I did go on to have a successful second pregnancy my daughter is now 3 and has positive blood.

  4. I am O negative and have 2 pregnancies my first I miscarried and was unaware of my blood type and didn’t receive the anti D injection with my second I had a successful pregnancy and received anti D injections 3 times once at about 10 weeks due to a bleed due to sex and again between 28-36 weeks and one after my daughter was born with both pregnancies when I had sex I bled and now my boyfriend is afraid to have sex with me I am 13 weeks if I bleed after sex can it mix with my baby’s blood and cause me to form antibodies.

  5. Hi my blood group is b+ and my wife is O- now she is pregnant, will it cause any problem to my wife are my baby will delivery. Please suggest me what I can do to protect.

  6. I m a man of O +’ve and my wife is O -‘ve. We once terminated a pregnancy. Please does my wife needs Anti D or she can get pregnant since it has been some time now.
    Thank you doc

    1. She would need to get a blood test to see if she has any antibodies in her blood. If hers and the baby’s blood mixed, she could have formed antibodies, meaning she will need to be under watchful eye during pregnancy. But if there have been no antibodies, she wont need anything unless bleeding happens during pregnancy, and after the birth.

  7. My blood type is negative,my first baby was not a problem…how will this effect my second child as I am 4+ months pregnant now?

  8. For a woman who has the first pregnancy and she is A- while his husband is A+, after what duration of pregnancy will she be needed to have the anti-D injection ?

  9. Am O+ MY husband is B- ,I received the ant-D with in72 hours after delivery of my first born am now expecting the second baby but i can not afford that injection now becouse of financial crisis were in now,but am woried if my baby is safe

    1. If you are Rh positive , even if your husband is Rh negative, there is no risk of Rh sensitization for you and you need not take anti D at any time

  10. What of people with has rh nagetive and have miscarried or aborted without been treated afterwards. Can they begin d treatment now?plss I really need to Knw.

    1. If they are already sensitised, then unfortunately you cannot reverse it. It requires specialist care for future pregnancies. A blood test will tell if they are or not.

      1. Hello Dr this is Nervise.am O- and my husband is B+We have our first baby and now we have had two miscarriages.but I have been taken my Anti D injection.wat could be the problem.

  11. I have my beautiful little girl and I really want to have another child. I am rhesus negative. Is it possible to have a completely normal pregnancy even with the condition or will the baby always have to have blood transfusions and blue lights for jaundice? I also have cerebral palsy and i fell alot with my first child. being that I didn’t have a whole lot of help while I was pregnant and had to take the unleash trained dogs outside by myself and they pulled my down onto my belly. So my third question would be how hard of an impact would you have to have to cause bleeding? I told my ob that i had fallen every time and he never seemed concerned about bleeding. Please give me answers. i would love to have another kid but wouldn’t dream of bringing one into this world if it is just going to suffer.

    1. I’m a rhesus positive mum n my husby negative. I have a baby girl who is Rh negative and I’m pregnant again. Do I need an anti D injection

  12. so I am a+ and my first daughter is being told she is o- she is now pregnant with her first and needs the shots. I don’t know my ex husbands blood type. Iis it possible for her to truly be o-.?

  13. My blood group isO+ and my husband blood is A+ then during pragnency or after child birth will there be any prblm please suggest

  14. I previously had a miscarriage at 6 weeks, almost 2 years ago. I’m now currently 7 weeks pregnant after 1 year of ttc. I only found out today, due to looking at my own baby book with my mum, that my blood type is o negative. I’m not sure what blood type my boyfriend is. I had a small amount of fresh blood bleeding at 6+1, and the midwife put it down to implantation bleeding. My scan showed a strong heartbeat and everything looked ok. Should I now be concerned that I’ve discovered my blood type, given my history of the miscarriage and being pregnant again?

  15. I am o- and my husband is o+. I had miscarriage march this year without any anti-D injection. now I am pregnant (6 wks) but bleeding. what is the cause? can I have a safe baby?

  16. I am 0+ and my husband is o- I hard miscarriage before and I am pregnant now. Is there going to be any need for me to be injected of anti rhesus.

    1. It’s likely the baby’s and your blood didn’t mix, but the easy way to find out is to ask your doctor to test for antibodies in your blood. If you don’t have them, you’re fine, but if you do have antibodies, your doctor will need to monitor the pregnancy.

      1. Thanks, Kelly! I’m also O+ and hubby is A+ and just had a D&C yesterday after a miscarriage so there was some concern (I didn’t know my blood type until calling this morning for results). Glad I stumbled across this. Thank you!

  17. I’m O- and my boyfriend is O+ I terminated 1 month pregnant 3-4 years back with my ignorance, but I want to marry very soon and I don’t know the step to take in order to know my stand. Please I need your advice.

  18. Hello I need help, Im 25 weeks pregnant and A blood type with rh negative, I had an abortion last year and didn’t get an anti-D since I didn’t know my blood results then.Will my baby going to make it? #confused

      1. I’m very worried I’ve have 2 boys 1 abortion and 2 misscarages, that’s not counting I’ve taken several plan b and took once medication to get a period. I’m AB rh negative always received the rhogam shot including one this month after my misscarage, prior to that I took medication to induce a early termination, could that have been the cause of my present misscarage? Will I ever be able to have one more child? Or is there a limit to being Rh factor?

  19. Hi I’ve had miscarige 3x last two days I had sugery to be remove missed miscarrige no heart beat, I am A+ positive do I need injection anti D ?
    And how get it
    Please tell me

  20. I previously had a miscarriage of 6 weeks last month my blood group is Ab- and my husband blood group is o+.. I want to know about next pregnancy. If i get pregnant after two months how can i protect my pregnancy pls suggest me. ..

  21. I am 23 years old. I may be pregnant, but was pregnant before. The doc tested my blood and it is O- and gave me an anti D shot. I am scared to death for my second child. I received this shot early September of 2014. I lost my baby September 10th, 2014. Do I need to get another shot? Do I need to worry? Please help! I can’t lose another child and survive…. I can’t go through it again.

  22. I’m ab- and my husband is b-.i had one mc after 10weeks in September 2015. I did take anti-d injection.now I’m pregnant again.5weeks and have pinkish discharge from 2 days.what should I do? Please give me some advise as soon as possible.

  23. I am going to try for my first child. My blood is B- and husband AB+ . Should I take the injection before my first pregancy

  24. I aborted a prenancy last year, before the operation the doctor told me that my unborn child was + and but my blood type negative; I didn’t know my blood type at that time. Because of the situation that pushed me to do the abortion i did’nt pay particular attention to doctor’s explanation about the risk involved in aborting my first baby given the reason that iam negative and the baby was positive. I was devastated with the pregnancy that couldn’t think clearly to make a rational decision by saving the child’s life for the sake of my future children. Iam now scared as to whether I am sentitized or not. It is possible that the abortion might have caused blood mixing which makes me prone to the development of the antibodies? Do the abortion clinics give anti-D injection when they find out the mother’s and baby’s blood to do match? They gave me injection but I didn’t know what it is for. Please, I want to know what steps to take before I get pregnant in the future? Please Doctor, give me answers.

  25. I am o- and my partner is o+ and we tried having kids twice and I have two miscarriages, I informed my doctor about this and she didn’t really told me all these info that am reading here , now am confused cause I had to change my ob . But am happy for this info it have informed me very well .

  26. My wife is 9 weeks pregnant her blood group is B- and I am B+ we found out about her pregnancy when she got an MRI done on her Knee along with some X Ray’s what are our changes of having a safe delivery or is there some thing that we should look at getting done .

  27. I am O negative and my husband is A negative.my first child is A negative . I never took anti D injection. But now I am 3 months pregnant and started to bleeding. Dies it has something to do with this rhesus factors. Kindly advise

  28. Am A negative. while my husband is positive presently Am 33 weeks pregnant should I wait till delivery before taking d injection or go for it now during pregnancy. pls advice

    1. yes it is possible…. as most people with rh positive are actually rh (+ -), so it is possible that the mother is A (+ -) and the father is O (+ -), and it is possible for the baby to have inherited both negative rh factor from each parent , so she has antigen A with rh (- -), making her A negative.

  29. I’m O positive and my wife is O negative we did go for blood test before getting married but after the marriage we did and get to find out this way. Currently she is not pregnant so I want to know the implications when she get pregnant and what will happened to our baby during and after birth and also what will happened to my wife?

  30. @Donna and Ann, there is absolutely no problem if the mother is positive and father is negative. Problems occur ONLY when mother is negative and father is positive.

  31. i am Rh o Neg I had my first child without takin the injection and we were both save but my second pregnacy there was complication befor child brith which makes my delivery to be premature and that lead to the death of d child after that i had 2 other children wit save delivery. and later did an abortion is there stil any need 4 me 2 take d injection if i stil want 2 hav another child. but my husband is positive.

  32. This is my first pregnancy, I’m b- and my son’s father is o+. I’ve been given the rograhm shot (sorry if its misspelled) every 12-15 weeks. My doctor has blood tests ran to check my antibodies and if they are at a certain level I have to have the injection. Im 36 weeks, and haven’t had to have the injection since my 2 nbt d trimester. I used to get extremely ill with migraines and severe abdominal pain with spotting, the first time it happened I was 10 weeks and It was so bad i thought I was havin a miscarriage. But as I got farther along it got a lot easier. The doctors say I’m missing 2 parts of my blood and my body sees my baby as an infection and tries to “fight” him off. But I have to have the injection within 72hrs of giving birth to my son and then another shot a few weeks later as a “just in case” according to my physician.

  33. I am 0- and my husband is B+ and I am pregnant now. And if I get any problem while am travel before delivery what I can do to protect my baby
    Please help me?

  34. If mother had 2 abortion in Rh negetive now she is pregnant third time what are the complication
    Is the baby is in danger

  35. To whom it may concern
    my wife is pregnant and the doctor told her she was late for the rhesus so they is no need for the injection what can be done?

  36. Please my blood group is b+ and my RH factor is positive, o don’t know that of the baby yet..so if the pregnant women RH is positiv,, does it affect the child

  37. I terminated a pregnancy 13 years ago even more than once, now I am married to the same person I just discovered that I am o- – rhd and my husband is B+ and I am heavily pregnant who’s blood gp is B+, I just learnt about this anti D injection, do I stand at any risk for not taken the injection when I had my first pregnancy removed without taken the injection.

  38. i am A+VE and ma husband is b-VE..and i would like to knw that if it becomes a prob..we havent had any kids now..just would like to knw if it causes any probs..

  39. I am currently 7 weeks pregnant I am RH negative. my boyfriend is positive. ive had an abortion 2 years ago. will this effect my baby in any way? am I already at high risk pregnancy?

  40. I am o- as are my first two children. I received the shot at 28 weeks with both children….. My doctor is concerned because after receiving the shot twice, I am now having to have 3 antibody screenings this pregnancy because I’m showing high levels….. He said that’s not normal? Has this really ever happened to anyone else?

  41. I am the mother of a positive blooded child .. I am rh negitive .. my son received blood transfusions in the womb because of my antibodies .. after he was delivered at 7 months .. he continued to receive blood transfusions because he couldn’t make blood anymore .. today he is healthy .. I am thankful to the doctors!! I spent almost my whole pregnancy in the hospital ..

  42. I am o positive and my wife is a negative my First child Very good but last abostion after my wife did not get anti d injection. please sujest me next pregnancy

    1. If the blood of the baby mixed with the blood of the mother, the mother will have antibodies. It will be important to make sure she is tested to see if she has antibodies, because if she does, it will be a high risk pregnancy.

  43. Hi. I have a serious problem about my RH and desperately need advice or help. I had two miscarriage with two babies (9months, and 6months) because my Rh problem. I have 3 babies now and they were my first (twins 8 years old) that I didn’t took the Rh shot after I gave birth to them. And then I got a boy (5 years old) and I got my RH shot after giving birth to him. After that I got pregnant two times . my third pregnancy was ok until my 9th month I started to feel sick and not ok and when I went to my Dr she said my baby have bad anemia and his brain stopped and he is almost dead so had to go in emergency room to get a c-section and the same happen with my 6months baby but with her it was little bit earlier (32 weeks) . the dr said it’s because I didn’t took the RH shot after my first pregnancy. So my question now I want get pregnant but scared of this may happen again . My dr also said that I can clean my body of the antibodies by using an dualism machine and get pregnant normal . Also he said I can try to take the shot during my pregnancy like my 3th month and my 6th months of my pregnancy. My question is it right information he gave me?. And if it’s not is there any way I can get pregnant again? Without any problems. Please hope you will reply to me . Thank you so much .

  44. I am now 45 ,I am A-,I had my first daughter and had an injection after as her dad was +,my second pregnancy ended in miscarriage at 6 weeks I also had the anti D injection after this,I then had another two daughters and had the injection again after them ,I then had a late miscarriage at 16 weeks after which I was given the injection,8 months later I had another miscarriage at 10 and a half weeks and was given the anti D injection,two years later I had my son I started to bleed at the beginning and was given the injection again but because I had three miscarriages the nurse said she would prescribe me low dose aspirin as it can help,I had injections all the time but still had miscarriages I did have healthy pregnancies but think I would of lost my son if it weren’t for the low dose aspirin apparently you can get sticky blood and aspirin helps thin it

  45. Hi, my blood type is O- I was given Rhogham injection before and after delivery of my first child, but during the second pregnancy I didn’t remember to take the injection. Am I and my second child at risk of any sort?

    1. It’s not you who should remember my doctor knew to give me the shot every time I was pregnant. If I didn’t get the shots (I got 3 ) with my last pregnancy my baby wouldn’t have survived cus he has his father s blood type I was told.
      You need to get the shot every time you are pregnant.

  46. Hi ,
    I’m 24 and I had a miscarriage at about 7 weeks in January, I’m 11 weeks pregnant now.
    I’m A- and my partner is A+
    I’m worried because I didn’t have a d-shot after my miscarriage my doctor never took my blood to find out my blood group and when I fell pregnant this time my new doctor did and said I should of had a d-shot
    Now I’m worried …

  47. I’m O+ and my husband is B – our first child had a high bilirubin after she was born because she’s also B-, but I never received any injections. I’m now 5 months pregnant with our second child should I be worried.

  48. I am O – and my fiance is O +. I terminated my first pregnancy in 2013 but I didn’t receive the Rhogam shot because I was unaware of my blood type. I had a miscarriage in 2017 and I received the shot then. I would like to try for another baby but I am scared that because I didn’t receive the shot the first time I may have built up antibodies. Is it possible that the shot I received in 2017 should get rid of any antibodies that may have formed after my termination in 2013? Also has this type of pregnancy been know to produce children with birth defects or special needs? Please help.

  49. I got tested and I have antibodies he said it just shows up a little will my baby and me be fine I am 8 weeks and 6 days I am so nervous about this I have never had antibodies With my 2 other kids

  50. Please Doctor I need your help on this. I put to birth October 22, 2018 but I lost the baby after birth because all effort to make him cry was abortive and ever since i came across this RHESUS FACTOR TOPIC i have been thinking otherwise. I am AB+ and my husband is B- is this rhesus factor compatible?

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