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Pregnant WomanLike many other women, I found out my blood type when pregnant with my first child. The midwife updated my records, circling my blood type with a red pen, and that was it.

Then, at 16 weeks pregnant I tripped and landed straight on my stomach. I was admitted for observation and it was at the point that my RhD negative blood started to matter. They did an antibody screen and it became obvious that my body was producing antibodies to rhesus positive blood – i.e. my daughter’s. I was given an injection and the rest of the pregnancy progressed smoothly.

But, had the midwife not highlighted my blood type, it could have turned out different, especially in my second pregnancy with yet another rhesus positive baby.

Rhesus Negative Blood

11% of Malta’s population has rhesus negative blood, but only a few know what it means, especially when it comes to pregnancy. We’ve enlisted the help of Dr. Christine Zammit Zerafa, an obstetrician and gynaecologist from MyMama, for the lowdown on rhesus negative blood, and how this affects your pregnancy care and the birth. Read on to learn more!

For personal support throughout your pregnancy and beyond, check out Dr. Christine’s services offered through MyMama.

I have rhesus negative blood. What does this mean?

Rhesus factor is an inherited protein found on the surface of red blood cells. Red blood cells carry haemoglobin, which in turn carry oxygen, around the body. A person is Rhesus negative if his / her blood lacks the protein, and Rhesus positive if his / her blood has the protein.

When does being rhesus negative become worrying? Can it affect the baby?

Rhesus FactorThe Rhesus factor is one of the factors that determines whether the blood of two different persons is compatible when mixed. This is one of the factors which is checked before a person receives blood from another person (blood transfusion).

If blood from a Rhesus negative person mixes with blood from a Rhesus positive person, cells which form part of the immune system and whose function normally is to protect the person’s body, will start producing antibodies. These are factors which will attack the red blood cells of the Rhesus positive person. In this way, red blood cells are destroyed and wouldn’t be able to function properly.

Carrying a baby who is Rhesus positive

Examining pregnant woman rhesus positive babyThis becomes very important if a pregnant woman who is Rhesus negative is carrying a baby who is Rhesus positive.

Under normal circumstances, during pregnancy, the blood of the foetus and mother do not usually mix together. However, mixing of blood might occur if there are bleeding episodes during the pregnancy, childbirth, miscarriage or ectopic pregnancy or trauma to the abdomen.

The reactions mentioned earlier might damage the baby’s red blood cells. This results in serious health complications to the unborn foetus. Serious health risks do not usually occur during a Rhesus negative woman’s first pregnancy with a Rhesus positive foetus, because her body does not have a lot of chance to develop antibodies.

However, the chances of serious health problems increase with the second and further pregnancies. This occurs since during these, the number of antibodies increase.

The Rhesus Status of a Pregnant Woman

The Rhesus status of a pregnant woman may be checked by a simple blood test, which is usually done during the first trimester of pregnancy. However, the Rhesus status of the foetus is not usually checked during pregnancy.

If the woman is rhesus negative and there is a possibility that her foetus is Rhesus positive, the obstetrician will also request an antibody screen. In turn, this will check whether the Rhesus negative woman has produced antibodies to Rhesus positive blood. The latter test is also done during the first trimester. This is usually repeated at 28 weeks.

We’re aware that rhesus negative women receive additional injections during pregnancy. When are these given and why?

Receive an injection anti-dRhesus immunoglobulin (or more commonly known as anti- D) is a medication which stops the body from producing antibodies against Rhesus positive blood. This can prevent health complications for the foetus, especially in a future pregnancy.

Therefore, anti-D is given to Rhesus negative women who are pregnant with a possible Rhesus positive foetus. Anti- D is given as an injection, usually at around 30 weeks of gestation. It is also given within 72 hours of childbirth.

The Anti-D may also be given after a miscarriage, ectopic pregnancy or trauma to the abdomen.

Can we still do delayed cord clamping if I’m rhesus negative?

Yes, delayed cord clamping is still possible in the case of Rhesus negative women.


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