Rh negative blood type and second pregnancy

Rh Negative Blood and Pregnancy

Rh negative blood type and second pregnancy

As soon as your pregnancy is confirmed your midwife or doctor will recommend blood tests to determine your immunity to various illnesses, as well as your overall health, your blood type and your Rh factor. Not everybody knows what their blood type is as it generally doesn’t affect us in a day-to-day sense. However in pregnancy it becomes important, as does the knowledge of whether you are Rh positive or negative.

What do Rh negative and Rh positive mean?

Everyone has a blood type (O, A, B or AB) and also a positive or negative rhesus or Rh factor. If you are Rh negative (also referred to as Rh (D) negative), this means your red blood cells do not have the D antigen. The D antigen is a protein carried on the red blood cells of people who have Rh positive blood types. Seventeen percent of the population are Rh negative and this is also influenced by ethnicity.

What is the significance of Rh negative blood and pregnancy?

A foetus inherits its blood type from both its mother and its father, therefore your baby may not have your blood type. An Rh negative mother for instance may carry an Rh positive baby.

Normally this isn’t an issue unless the foetal blood enters the mother’s blood stream. If this occurs then the mother’s body will develop antibodies to destroy Rh positive antigens because it recognises these as foreign cells. This is quite similar to the way the human body develops antibodies to fight viruses and provide ongoing immunity when a person comes into contact with a transient illness.

If the mother’s body develops antibodies to Rh positive blood then this can have catastrophic effects on future pregnancies as the antibodies cross the placenta and attack the foetus’ positive red blood cells. This can cause severe anaemia, fluid retention, swelling and brain damage in the foetus, and potentially foetal heart failure and death. This condition is called Haemolytic Disease of the Newborn or HDN.

How can foetal blood cross into the mother’s blood stream?

Foetal blood can cross into the mother’s blood stream without the mother being aware of it. The most likely time this will happen is during childbirth thus affecting future pregnancies. Times when foetal blood may cross into the mother’s blood stream include:

  • Childbirth (affecting future pregnancies)
  • Miscarriage beyond 12 weeks gestation
  • Ectopic pregnancy
  • Termination of pregnancy
  • Amniocentesis
  • Chorionic Villus Sampling (CVS)
  • Vaginal bleeding during pregnancy
  • External Cephalic Version (ECV)
  • An accident resulting in a hard blow to the stomach

Who is at risk?

Only mothers who have Rh negative blood are affected in pregnancy. Mothers who are Rh positive are not affected even if their baby is an Rh negative blood type. If an Rh negative mother is carrying an Rh negative baby then this will not affect her or her baby in this pregnancy. However we do not commonly know our baby’s blood types before birth to determine if the baby is Rh positive or Rh negative.

How can Rh negative mothers protect their pregnancies?

If you have an Rh negative blood type your caregiver will recommend you receive two injections during pregnancy, at 28 weeks and 34 weeks respectively, and a third injection following childbirth. These injections are Rh (D) immunoglobulin, commonly referred to as the anti D injection, which means they prevent the mother’s body creating antibodies to fight the positive blood group of this foetus or future foetuses. It is important to note that if the mother already has the Rh antibodies, the immunoglobulin will be ineffective as it is a preventative only.

The anti D injection is made of blood plasma and has been used since the 1960’s with no major adverse reactions known to affect either the mother or the foetus. In rare cases it may cause a mild allergic reaction in the mother such as a rash or flu-like symptoms. Therefore it is advisable to remain at the hospital or doctors clinic for 20 minutes following the first injection.

What happens if I develop Rh positive antibodies?

The development of antibodies against Rh positive blood is called rhesus disease and occurs in 16% of Rh negative women if not given the anti D injection. This is referred to as sensitisation which means the antibodies easily cross the placenta into the baby’s amniotic fluid and blood stream via the umbilical cord in future pregnancies.

If rhesus disease is present then the level of sensitisation will determine the level of monitoring or interventions needed. If levels of antibodies are low then your baby may not require any treatment. In more serious cases s/he may require phototherapy, a treatment used for jaundiced newborns. Your baby may also require blood transfusions in utero or after birth to speed up the removal of bilirubin in his/her blood.

Bilirubin is produced during the normal breakdown of red blood cells. When bilirubin is present in quantities above what the liver can excrete, it causes an orange tinge to the skin and eyes known as jaundice, which we sometimes see in newborns.

Need more information?

The Australian Red Cross Blood Service (2010) has produced an informative, easy to understand brochure for pregnant women who are Rh negative which can be found here. Your midwife or doctor will also be able to provide you with information regarding Rh negative blood types and the anti-D injection.

Article written for Pregnancy Birth and Beyond on 14 th October 2014


Australian Red Cross Blood Service 2010, You and your baby: important information for Rh (D) negative women, CSL Biotherapies, Australia.

Dean, L. 2005, Blood groups and red cell antigens, National Center for Biotechnology Information, United States.

National Health Service 2013, Rhesus disease, United Kingdom.

NSW Health 2014, Maternity – Rh (D) Immunoglobulin (Anti D), Sydney.

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Discovering Your Blood Type and Rh Factor

You’ve discovered you are pregnant and now you have some routine blood tests that are done to determine your blood type and your Rh status. Rh (Rhesus) factor refers to a specific antigen in the blood found on the surface of the red blood cells.

When a mother is Rh-negative and the father is Rh-positive, the baby can inherit the Rh factor from the father, making the baby Rh-positive as well. If you are Rh-negative there’s a pretty good change your blood is incompatible with your baby’s blood, which will likely be Rh-positive. There is no way to know the baby’s Rh factor until birth, but it’s safe to assume it is Rh-positive. The statistics indicate that if the father is Rh-positive and the mother Rh-negative, there’s a 70% chance of having an Rh-positive baby. If both parents are Rh-negative, then the baby will be Rh-negative as well.

What Happens When Blood Mingles

If this is your first baby, then being Rh-incompatible probably will do no harm to you or your baby.

Taking Precautions

Normally in pregnancy the baby’s blood stays separate from the mother’s blood and very few cells cross the placenta. Actually, it is unlikely the blood will mingle until the time of delivery. That’s why Rh-negative factor isn’t usually a problem with the first pregnancy. If your blood mixes during delivery you’ll have given birth before your body has a chance to make antibodies against the Rh-positive blood, so there will be no problems.

A shot will be necessary is your baby is Rh-positive (which will be discovered after the baby is born). If you were exposed to Rh-positive blood during delivery, the shot will prevent your body from making any antibodies that could attack a future baby with Rh-positive blood. The blood samples taken from the baby’s heel and the cord are tested for several things, among them Rh factor. Without treatment there’s a 15% chance you’ll develop antibodies, but with the shot, the risk is virtually nil.

When It Is Too Late for the Shot

If you are Rh-negative, have been pregnant before but didn’t the shot, a routine prenatal blood test will tell whether you have the antibodies that attack Rh-positive blood. If so, then it is too late to get the shot and, if the baby is Rh-positive, then some problems may be on the horizon for him. If you don’t have the antibodies, then the shot will protect you from developing them. There are a few situations in which your baby’s blood might mix with yours. If you miscarry or have an abortion, or an ectopic or molar pregnancy the risk is there. An invasive procedure like amniocentesis or chorionic villus sampling increases the chances as well. Vaginal bleeding, injury to the abdomen during pregnancy and stillbirth are other situations in which the baby’s blood may mix with yours.

Proper treatment can ensure a safe and healthy delivery for both mother and baby.

Blood Type Origins – Rh Negative

Rh negative blood type and second pregnancy

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Rh negative blood type and second pregnancy

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Rh negative blood type and second pregnancy

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Rh negative blood type and second pregnancy

I have Rh Neg. I was born in Espelette-Basque Country.

Rh negative blood type and second pregnancy

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Rh negative blood type and second pregnancy

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Rh negative blood type and second pregnancy

I am O- and half German and half British. So what?

Rh negative blood type and second pregnancy

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Rh negative blood type and second pregnancy

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Rh negative blood type and second pregnancy

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Rh negative blood type and second pregnancy

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Rh negative blood type and second pregnancy

I am African American woman and my Blood Type B Negative.

Rh negative blood type and second pregnancy

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Rh negative blood type and second pregnancy

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RH Incompatibility

by Admin · November 11, 2007

Rh incompatibility is a condition which develops when a pregnant woman has an Rh-negative blood type and the fetus she carries has Rh-positive blood type.

The Rh factor (ie, rhesus factor) is an red blood cell surface antigen that was named after the monkeys in which it was first discovered. Rh incompatibility, also known as Rh disease, is a condition that occurs when a woman with Rh-negative blood type is exposed to Rh-positive blood cells, leading to the development of Rh antibodies.

Rh incompatibility can occur by two main mechanisms. The most common type occurs when an Rh-negative pregnant mother is exposed to Rh-positive fetal red blood cells secondary to fetomaternal hemorrhage during the course of pregnancy from spontaneous or induced abortion, trauma, invasive obstetric procedures, or delivery. Rh incompatibility can also occur when an Rh-negative female receives a blood transfusion that contains Rh antigens. In part, this is the reason that blood banks prefer using blood type “O-negative” or “type-O, Rh negative,” as the universal donor type, especially in females.

The most common cause of Rh incompatibility is exposure to an Rh-negative mother by Rh-positive fetal blood during pregnancy or delivery, whereby red blood cells from the fetal circulation leak into the maternal circulation. After a significant exposure, sensitization occurs and maternal antibodies are produced against the foreign Rh antigen.

Once produced, maternal Rh immunoglobulin G (IgG) antibodies may cross freely from the placenta to the fetal circulation, where they form antigen-antibody complexes with Rh-positive fetal erythrocytes and eventually are destroyed, resulting in a fetal alloimmune-induced hemolytic anemia. Although the Rh blood group systems consist of several antigens (eg, D, C, c, E, e), the D antigen is the most immunogenic; therefore, it most commonly is involved in Rh incompatibility.

Causes, incidence, and risk factors

During pregnancy, red blood cells from the fetus can get into the mother’s bloodstream as she nourishes her child through the placenta. If the mother is Rh-negative, her system cannot tolerate the presence of Rh-positive red blood cells.

In such cases, the mother’s immune system treats the Rh-positive fetal cells as if they were a foreign substance and makes antibodies against the fetal blood cells. These anti-Rh antibodies may cross the placenta into the fetus, where they destroy the fetus’s circulating red blood cells.

First-born infants are often not affected — unless the mother has had previous miscarriages or abortions, which could have sensitized her system — as it takes time for the mother to develop antibodies against the fetal blood. However, second children who are also Rh-positive may be harmed.

Rh incompatibility can cause symptoms ranging from very mild to fatal. In its mildest form, Rh incompatibility causes hemolysis (destruction of the red blood cells) with the release of free hemoglobin into the infant’s circulation.

Hemoglobin is converted into bilirubin, which causes an infant to become yellow (jaundiced). The jaundice of Rh incompatibility, measured by the level of bilirubin in the infant’s bloodstream, may range from mild to dangerously high levels of bilirubin.

Hydrops fetalis is a complication of a severe form of Rh incompatibility in which massive fetal red blood cell destruction (a result of the Rh incompatibility) causes a severe anemia resulting in fetal heart failure, total body swelling, respiratory distress (if the infant has been delivered), and circulatory collapse. Hydrops fetalis often results in death of the infant shortly before or after delivery.

Kernicterus is a neurological syndrome caused by deposition of bilirubin into the brain (CNS) tissues. Kernicterus develops in extremely jaundiced infants, especially those with severe Rh incompatibility.

It occurs several days after delivery and is characterized initially by loss of the Moro (startle) reflex, poor feeding, and decreased activity. Later, a high-pitched shrill cry may develop along with unusual posturing, a bulging fontanel, and seizures. Infants may die suddenly of kernicterus.

If they survive, they will usually later develop decreased muscle tone, movement disorders, high-pitched hearing loss, seizures, and decreased mental ability.

Rh incompatibility develops only when the mother is Rh-negative and the infant is Rh-positive. Special immune globulins, called RhoGAM, are now used to prevent this sensitization. In developed countries such as the US, hydrops fetalis and kernicterus have decreased markedly in frequency as a result of these preventive measures.

The amount of fetal blood necessary to produce Rh incompatibility varies. In one study, less than 1 mL of Rh-positive blood has been shown to sensitize volunteers with Rh-negative blood. Conversely, other studies have suggested that 30% of persons with Rh-negative blood never develop Rh incompatibility, even when challenged with large volumes of Rh-positive blood. Once sensitized, it takes approximately one month for Rh antibodies in the maternal circulation to equilibrate in the fetal circulation. In 90% of cases, sensitization occurs during delivery. Therefore, most firstborn infants with Rh-positive blood type are not affected because the short period from first exposure of Rh-positive fetal erythrocytes to the birth of the infant is insufficient to produce a significant maternal IgG antibody response.

The risk and severity of sensitization response increases with each subsequent pregnancy involving a fetus with Rh-positive blood. In women who are prone to Rh incompatibility, the second pregnancy with an Rh-positive fetus often produces a mildly anemic infant, whereas succeeding pregnancies produce more seriously affected infants who ultimately may die in utero from massive antibody-induced hemolytic anemia.

Risk of sensitization depends largely upon the following 3 factors:

1. Volume of transplacental hemorrhage

2. Extent of the maternal immune response

3. Concurrent presence of ABO incompatibility

The incidence of Rh incompatibility in the Rh-negative mother who is also ABO incompatible is reduced dramatically to 1-2% and is believed to occur because the mother’s serum contains antibodies against the ABO blood group of the fetus. The few fetal red blood cells that are mixed with the maternal circulation are destroyed before Rh sensitization can proceed to a significant extent.

Rh incompatibility is only of medical concern when transfusion is needed and during pregnancy. Rh positive antibodies circulating in the bloodstream of an Rh-negative woman have no adverse effect in the nonpregnant state.





RH Incompatibility