How To Determine and Manage Rh Incompatibility

Dr. Greene, my Blood Group is B, Rh negative; my husband’s Blood Group is A, Rh positive. We already have a child, but we want to have another one. My last blood analysis shows that my anticorps Anti-Rh were very high. The question is: Can I have another child?
Corina Oteanu – Bucharest, Romania

How To Determine and Manage Rh Incompatibility

Dr. Greene’s Answer:

Corina, your situation is both dangerous and precarious.

Every snowflake is different and each person is even more so! Each cell in our bloodstream carries our own genetic signature. A constellation of proteins on the surfaces of the cells allows our bodies to distinguish between our own blood and someone else’s. These protein patterns are roughly divided into groups that we call blood types.

Not only are blood types different but some types of blood are incompatible with some others. The white blood cells in some types will perceive other types as enemies, attacking and destroying the other blood. This problem is most significant in people with Rh incompatibility.

People are called Rh-negative if they do not have the rhesus (Rh) protein on the surfaces of their blood cells. If Rh-positive blood cells get into the bloodstream of someone who is Rh-negative, the body of that Rh-negative person will see this as an enemy invasion.

Unprepared, the Rh-negative person will begin to make antibodies (what you call anticorps) against the foreign Rh protein. This first exposure is often not even noticed. The next time an exposure occurs, though, the body is primed to seek and destroy all Rh-positive blood cells. All-out war can occur inside an Rh-negative person’s body.

A terrible condition called hydrops fetalis can be the result of that war. Rh incompatibility produces a wide variety of outcomes. Sometimes only mild anemia and perhaps a little jaundice are the only signs there has been a conflict.

But sometimes the results are catastrophic. The first pregnancy is rarely a problem because blood is often not exchanged until the time of birth. But with each subsequent pregnancy, the risk for hydrops increases.

Hydropic babies are bloated, swollen, and pale. Enlarged hearts, livers and spleens are unable to perform their vital duties. The swollen lungs can make breathing impossible. Many hydropic babies are stillborn. Many die shortly after birth.

In 1963 an event occurred that began to change the story. Jorg Schneider, who was at the Freiburg University Hospital in Germany at the time, became the very first investigator to give pregnant, Rh-negative women a shot of Rh antibodies to prevent their immune systems from mounting their own response to Rh-positive cells.

The exact date of this achievement was August 9, 1963. One year later, Schneider reported that nine women, following delivery of Rh-positive children, did not develop Rh antibodies during subsequent pregnancies with Rh-positive fetuses.

Since then, prevention programs have been implemented in many countries around the world. In Great Britain, the number of deaths from hydrops has dropped 96% in the years since the prevention program began in 19701. This experience is typical.

By giving anti-D globulin (RhoGAM) to Rh-negative moms during and shortly after each pregnancy (including after miscarriages and abortions), 99% of mothers will not develop anti-Rh antibodies.2 Unfortunately, about 1% still do.

Being Rh-negative is a recessive trait. This means that a person needs to have two negative genes to be Rh-negative and will always give one negative gene to any offspring. Being Rh-positive is a dominant trait. This means that an Rh-positive person can have two positive genes or one positive and one negative gene. If your husband has a positive and a negative gene, then about half of your offspring will be Rh-negative (and there should be no trouble carrying an Rh-negative child). But about half of your offspring will be Rh-positive (and if your mate has two positive genes, all of your offspring will be Rh-positive). This is a very risky proposition.

Healthy, Rh-positive children have been born to women with high titers, especially if they have had the RhoGAM and the titers are still high. Having a blood type B mom and a blood type A baby is also somewhat protective. But the pregnancy should be monitored closely and carefully managed by an expert in this area, even before conception. For a successful outcome, the baby may need blood transfusions every 3 to 5 weeks even before being born. Delivery is induced as early as is safe.

Even if birth is successful, the infant should be cared for at a well-prepared medical center. The baby may need aggressive treatment for anemia, immunodeficiency, and jaundice shortly after birth.3

When I was born, hydrops fetalis was an almost hopeless situation. Today, preventing Rh-negative moms from being sensitized is extremely (but not completely) successful at preventing hydrops wherever the guidelines are followed. All of this with a couple of simple, but ingenious shots! Once a mom has become sensitized things are not so simple. Future pregnancies may turn out fine, but sometimes massive, complex, medical interventions are necessary — and even with these, a good outcome may not be possible.

So, Corina, you have a very difficult decision to make. I’m afraid I cannot tell you whether you can safely have another child or not. But I do encourage you to weigh the odds, speak with your doctors, and to appreciate the beautiful, healthy child you already have.
Footnote References:
1 British Journal of Obstetrics and Gynaecology 1986 Sep;93(9):960-966
2 Williams Obstetrics, Appleton & Lange.1997
3 Pediatric Hematology Oncology 1998;15:193–197

Dr. Alan Greene

Dr. Greene is the founder of (cited by the AMA as “the pioneer physician Web site”), a practicing pediatrician, father of four, & author of Raising Baby Green & Feeding Baby Green. He appears frequently in the media including such venues as the The New York Times, the TODAY Show, Good Morning America, & the Dr. Oz Show.

  1. Angel Tompkins

    If the man I am planning to marry is O- and I am O+ what is the possible outcome of our children’s blood type, I have read the questions above and I am confused. What does Rh- and Rh+ stand for in medical language. I do want children who are healthy and I want more than one and I care for my own health and I live in a preventable way and do not look to cause myself or my future family problems in any way. The world around me has plenty.

    • Hi Angel,

      The issue with blood type incompatibility come when the mother is Rh-. There is no issue if the father is Rh-.

      Two people with type O blood will have children who are type O. This is the most common blood type.

      Your blood types should not cause any issues in having multiple children.

      Hope that helps,
      Co-founder and Executive Producer,

  2. Johnn

    Hay my mother is O+and the man she keeps telling me is my father is B+but yet I’m A-I’m confused about it all is there any possibility that he is my father because I’m A- and I try explaining it to my mother because I don’t believe that there is a chance at all

    • Hi John,

      One of your blood types may not be what you think it is, but the scenario you’ve outlined is not considered possible. Here’s why …

      Each person has two alleles that make up their blood type. The A and B alleles are dominant and O in recessive.

      — Type A = A & O or A & A
      — Type B = B & O or B & B
      — Type O = O & O
      — Type AB = A & B

      Each parent gives one allele to their child. In this example:
      — Type O can only give an O
      — Type B can give an B or an O

      The child can be:
      — Type O = O from one parent and O from the other parent
      — Type B = B from one parent and O from the other parent

      Before you draw any conclusions, though, it’s wise to have everyone retested. It’s possible that the original tests had an error, they were reported incorrectly, or people’s memory of their own blood type is in error.

      I hope that’s helpful,
      Co-founder & Executive Producer,

  3. Dave

    Doc. How is it possible for parents that are both O negative to have a baby that is O positive.

    • That is not considered a possible outcome.

      As I’ve said here many times — 1) our scientific knowledge is always growing 2) Retest before jumping to any conclusions.


  4. Sanida, Bosnia and Herzegowina

    Dr. Greene, my Blood Group is B, Rh negative; my husband’s Blood Group is A, Rh positive. We already have a son and daughter with Blood Group B positive. And in addition to regular income Rogham, after the second birth I became Rh sensitive , and I only found out in the 16th week of pregnancy third . Antibody titer in 16th week was 1 : 256 , in the 18th 1 : 128. My doctor says the baby is healthy and everything is fine , but to avoid any complications , it is better to do an abortion. Please, help me..What can I do?

  5. Yetty

    Dear Dr. Greene, I need your advice please. I am O+ while my hubby is B-. I have a son who had jaundice shortly after birth. My doctor didn’t mention anything about the cause and the need for injection to prevent my body building up antibodies. However, I recently stumbled on Rh incompatibility and I’m a little confused as we are planning on making another baby. Could you please advise me on what to do? Thanks for your time.

    • Muhammed

      Yetty, you will not need any injection as your blood type and is not B rhesus negative (B -). This particular injection is for rhesus negative mothers

  6. Brittany Crowley

    So I have a very important question my mother is -AB blood and my father is O- my mother seems to believe I have O+ but as I recall she said my blood type is the same as my dads


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