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O-Negative Blood Type & Pregnancy

Berkeley Parents Network > Advice > Pregnancy & Childbirth > O-Negative Blood Type & Pregnancy


August 2003

I just learned that I am O neg. blood type and my husband is a positive blood type. Evidently, there is some risk that the baby will have the positive blood type and my body will see it as a foreign invader and attack it somehow. some shot is supposed to take care of it. if anyone knows anything about this, i would appreciate information many thanks anon


A mismatch in blood types can be dealt with. Is this your first preganancy ever (i.e., no previous pregnancies that ended in miscarriage or termination)? If it is, then all you need is a shot of Rho-gam at a mid-point in the pregnancy and then again after the baby is born. Rho-Gam puts TEMPORARY RH-factor anti- bodies in the mother's blood so her body doesn't product its own, and the next baby gets a clean slate and you start the Rho- GAM shots over. If you've already had a pregnancy, make sure your doctor knows, because your blood will need to be tested for Rh-antibodies. You will still need the Rho-GAM shots for this pregnancy, but additional monitoring of anti-bodies may be required. The baby's blood will be typed at birth. If your husband is carrying a recessive gene for Rh-negative, you may end up with an Rh-negative baby anyway, in which case you won't need the second (post-birth) Rho-GAM shot. That's what happened to me. My ex-husband is O-positive and I'm O-negative and both our kids are RH-negative. Rho-gam has been around since the mid- 60's, so your doctor should be aware of it. Just make sure the doctor knows about your RH discrepancies. anonymous
My husband and I also have different RH factors. It is fairly common, and your doctor will know when you need the Rhogam (sp) shot, so don't worry about your body rejecting the baby. During my first pregnancy, I believe I was given a shot at some time during the pregnancy and again after birth- basically anytime your blood might mix with the baby's. I miscarried once and was given a shot after that as a precautionary measure to be sure that my body would not reject future pregnancies. Now, I am pregnant with number 2, and I received a shot after my amniocentesis. I expect they will have another for me after this baby is born. Susan
I am O neg and my kids' father is O positive. It turns out that my children are O positive which is no surprise given his blood type. The shot you need is called Rogam (spelling??). I had them in the middle of both pregnancies, at the end of the pregnancies, and after my two miscariages. It is extremely important you get these shots -- they are one of the wonders of modern medicine. It seems weird that pregnancy, which people now harp about how natural it is, naturally has this serious potential problem for O negative women with O positive mates. As recently as my mother's generation, O negative women sometimes lost their babies because of the incompatible blood type (I believe these were called ''blue babies'' because of how they looked when they were born.) So get your shot -- it's in the bottom by the way, but no big deal and I am a shot whimp. Brenda
You'll be getting a Rhogam shot at 28 weeks and then right after the birth. I had the same thing. It's not a big deal, but I understand that Rhogam contains thimerosol (mercury preservative) so for my next baby I will ask the doctor about that (I think there is a Canadian company that makes it without the thimerosol). Congratulations on your new baby! anon
I also have negative blood- my husband positive. Get the shot- RH I think it's called. I did not hear any negatives about it when I was pregnant last year nor did I read any. Good luck- and no worries! Juliette
My mother has O- blood and I am AB+. I am also her only child. Apparently, she had no problems carrying me to term, but she could not have any more children *after* me (except with a partner who also had O- blood type), because she was sensitized by her pregnancy with me. So, I don't know if you have to have a shot of any kind the first time -- it was fine for my mom - it might be fine for you! You might just need to consider your options if you want a second child. Then again, I'm no doctor, so maybe my mother's experience was exceptional? Best of luck! O- mamma
I too have 0 negative blood and my husband was positive. If your child is born with positive blood, you will be given a shot to prevent your blood from being tainted for future babies. Our first child was 0 positive, I was given the shot. I recently gave birth to our second child who is 0 negative. Our ob assured us that we had nothing to worry about (of course I didn't entirely believe him during our first pregnancy...but now I know I was needlessly worrying). Best of luck-
i am 0-negative as well. I got the shot a few weeks before pregnancy and then one right after i gave birth and everything was fine with me and my baby. i think as long as you get the shots everything is fine. good luck with the birth! 0-negative mom
This condition is referred to as Rh-incompatibility. It is NOT an issue in 1st pregnancies (miscarriages & abortions do count as pregnancies). If you are O negative they'll give you a RhoGam shot in your 3rd trimester, or if you are getting an amnio or CVS. In most pregnancies, mama & baby blood don't mix, it is just a precaution.

Here is a link to more information: http://www.babycenter.com/refcap/1480.html. It is also talked about in pretty much all the pregnancy books. another O neg mama


Don't worry! I am AB-negative (apparently the rarest blood type), and have had two children. After each birth I was given a Rho-gam shot and everything was fine. Back in the old days, having a negative RH-factor could have been a problem for a pregnancy, but these days it shouldn't be a worry. Just be sure you talk to your Dr. about it, too. -Alexis
I was surprised when I was pregnant to find out about this as well. I have A- blood type and my husband is O+. I was given a shot in, I believe, about the last month of pregnancy in case my child had RH+ blood type. My doctor also gave me a card that stated I was RH- and I informed the doctors and nurses about it when I went in for labor. I was so out of it during the birth that I'm not really sure what they did about it. It turned out that my son is RH- so it wasn't a problem. My doctor made me feel that it was not a huge deal. Just something they needed to know about and deal with at the time of labor. If you're feeling unsure, I would ask your doctor for more details about what the possible risks are. Good Luck with the new baby! Nancy
O negative means you need a couple of Rhogam shots during your pregnancy. Your OB should know all about it and at what point you need them done. I got them from my OB and it is totally routine and standard. Get the shots, it's not a big deal. anon
Check out this article, it should tell you all you need to know and if you have further quesitons you should ask your OB about it. http://health.discovery.com/diseasesandcond/encyclopedia/2093.html
I am o-negative too, and pregnant with my second. It's really no big deal anymore because of the shot your doctor told you about. You get a shot (at the drs office) of Rhogam (sp?) at 28 weeks, then another one right after the birth of the baby (within the first day or so), and then forget about it until you get pregnant again. Being o-negative and pregnant used to be an issue, but with the shot, it's not anymore. On the plus side, blood donation centers are always excited to see you... fellow o-
I am A negative and my husband is positive, and I have had 2 children. It is important that you understand the potential problem here, because it is very important that you know you are getting the appropriate treatment. First, this is only a problem AFTER the placenta barrier has been broken (by abortion, birth, amnio, or perhaps - I don't know for sure - by miscarraige) AND the baby in question has positive blood. Once the barrier is broken, the baby's positive blood causes your body to produce antibodies defending itself against the positive blood that has entered your system. (This is the same reason why people with negative blood can only have transfusions of negative blood and so should be regular blood donors if they can.) It is these antibodies that will fight any future introduction of POSITIVE blood in SUBSEQUENT pregancies. If this were allowed to happen, these antibodies essentially fight or ''kill'' the SUBSEQUENT baby's blood, thereby requiring intervention to save the baby (e.g. transfusions to the unborn baby and premature induction). The good news is that A) the production of antibodies in the mother is completely preventable (via a shot of Rhogam within 72 hours of the breaking of the placenta barrier) and B) the first baby may also be negative (so that you do not produce antibodies) and/or the second baby may be negative (so that your body does not fight its blood). How might your baby be negative? This may be simplistic, but it is basically this: You get a + or a - from each of your parents. Therefore, you and your husband, and every person out there, either has a positive/positive combination, a positive/negative, a negative/positive, or a negative/negative. Because negative is recessive, only the negative/negative combination manifests itself as negative overall (so you must have negative/negative, but your husband could be one of the other 3 combinations - i.e., he may CARRY a negative to give to your babies). If he passes on a negative, your baby will be negative. If he passes on a positive, your baby will be positive. It is up to him. As a case in point, my first baby was negative, but my second baby is positive. Of course they don't know what blood type the baby is until the baby is born. So, what do you do to monitor your care? You make sure that you get that Rhogam shot after the amnio if you get one and within 72 hours of the birth and you remind everyone who will listen that you are negative. In the US, they also give you a ''booster'' at 24 weeks or so, but in other countries (I had my 2nd baby in France) they don't. In my experience all of this is monitored very closely. When they told me that my first baby was born negative so I didn't need the shot, you bet I was wanting to see it on his chart, and that it had been confirmed and reconfirmed, because mistakes can be made. They won't give you the shot ''anyway just in case'' because it can cause jaundice (rare) I understand. Anyway, make sure you get it and be informed so you understand what the doctors are telling you. There is no need to be worried. Good luck! E-mail me if you would like to ask anything else. Jennifer
I'm in the same situation. I was given a shot of Rhogam after an earlier miscarriage, and am now planning to have a dose at 28 weeks, then another after childbirth. According to my OB, they think that Rhogam is effective for at least 12 weeks in preventing your body from becoming sensitive to Rh-positive blood, which would only happen if the baby is Rh-positive and your blood mixes. Heather
Don't worry. Things are much better these days. Yes, there is a risk, and you should mention it when you see your doctor or any other care provider. But it's not that big a problem now. And it's always been less of a problem witth first babies than with subsequent pregnancies. You'll get a couple of shots over the course of your pregnancy that will help your body cope with your baby if he or she is Rh + . Check with your doctor about the shots and when to take them, and then relax and enjoy your pregnancy. Carolyn
Congratulations on being the universal donor! I am Rh- (B-) also and have had two healthy pregnancies. I was given a shot or Rhogam (sp?) at 28 weeks pregnant with both pregnancies. With my first child, who is Rh+, I was also given a shot of Rhogam in the hospital. The shots are not too bad, only the location of the injection is not fun - in the rear end (however after giving birth twice getting a shot in the bum is not big deal). If this is your first pregnancy, you have nothing to worry about. An Rh- mother builds antibodies that would attact a second, third, etc. pregnancy if the first (or any other) child is Rh+. I now have two healthy children, one AB+ and one B-, and because the second one was Rh-, I did not have to get the shot in the hospital. Lisa
Dear anon, I too am an O-negative, and my husband has a positive blood type. We have a healthy baby that was born 18 months ago. He himself has a positive blood type too.

I remember the concern I felt when I found out what my blood type is...

This is how it works: First at the very early stages of the pregnancy your doctor should check to make sure you don't have anti bodies for positive blood type.The anti-bodies developed as a result of contact with a positive blood type. So, if this is your first pregnancy, there is a very slim chance that you have them, unless you were ever given positive blood type (what are the chances of that...) or something of a sort.

There is almost no risk to reject the baby on the first pregnancy. That is because until the actual delivery there is no contact between the mom's blood and her baby. Only in cases of a major bleeding the doctor will look into it.

In our modern world, there is a great invention that is called ''Anti D''. This vaccine shot will be given to twice during the pregnancy: you when you reach the 28th week of your pregnancy (at which point they will check again that you didn't developed any anti-bodies, which you won't), and within 72 hours of the delivery. The vaccine destroys the baby's white blood cells before the mom's immune system can identify them and reject them, and so no anti bodies are created. The vaccine only lasts a few weeks though.

So basically for the first pregnancy there's little to worry about. For your next pregnancies, you should just make sure you get the shot on time and all will be fine.

Being a O negative, as you know, you can give blood to anyone, but can receive only from O negative (even more specific than O positive that can give blood to all but O negative). I often wonder if our blood type has more indication of who we are than we seem to think...

If you have any further questions, please feel free to email me. Reut.


I didn't notice anyone mentioning something that happened to both me and my sister with newborn babies... We are both O- and married positive blood husbands. We had the rhogam.. and that is no big deal. But, both of our newborn babies were more susceptible to newborn jaundice. In the case of my sister, she left the hospital early (before 24 hours after the birth) and nobody caught the jaundice (because it often doesn't kick in for 24-48 hours). Her baby had to go back to the NICU for a couple of days because it had progressed to very high levels at home. It was really hard for her to have to bring her baby back to the hospital and keep it under lights when all she wanted to be doing was bonding at home. Also, she had to pump, right when her milk came in which was very painful. Knowing this, I stayed longer at the hospital and we monitored our baby very closely. She did get jaudice but we spent a lot of time with her undressed in near a sunny window and breastfeed more than typical (which is VERY frequent anyway with a newborn, I think I was breast feeding about 15 hours a day for the first week!)

Anyway, I'm not a doctor so my medical understanding of this is sketchy at best, but I did read somewhere that babies born with incompatible blood types as their moms are more susceptible to newborn jaundice. It's really not that big a deal, if monitored, and hopefully you can keep low through natural measures before it reaches elevated states. Congrats on your baby! ramsey


Someone mentioned that Rhogam contains thimerosol (mercury preservative), and I wanted to urge you to MAKE SURE if you get the Rhogam shot that it does not contain thimerosol. They might be making it only without thimerosol now, but I'm not sure. Mercury can have a serious adverse effect on your baby, though you may not have any idea that it's related to the shot. We are pretty sure this happened to our son, who has a mild neurological problem that has nonetheless had a significant impact on our lives. I wouldn't want him to be any different from what he is, but still, to make life a bit easier for him, I wish I knew then what I know now. See previous Mothering magazine articles on the subject if you don't know what I'm talking about (some are probably on their web site). Much of the info is in their articles on the Mercury-Autism connection. anon
Oct 2006

As a student of Biomedical Engineering, I would like to clear up a few misconceptions on this board:

1- this "blue baby" phenomenon has nothing to do with blood types A, B, AB, and O. It only concerns the + and - markers (called antigens). Only worry if the mother is - (negative) and the father is + (positive). This can be done by a simple blood test.

2- AB+ is NOT the rarest blood, but it is the 'universal acceptor' because it can take A and B and + antigens(O and - are actually a lack of antigens, and all immune systems accept 'nothing' on blood cells). O- is the 'universal donor' because it has no antigens, so it's accepted by all immune systems.

Also, the long post by Jennifer is GREAT. Read it twice.


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