Rh Factor, Atypical Antibodies, and the Anti-D Injection in Pregnancy
Learn how Rh factor antibodies affect pregnancy, why Anti-D injections matter, and how doctors protect your baby.
In short: If the mother is Rh-negative and the father Rh-positive, the mother may form antibodies that cross the placenta and attack the baby’s blood, causing anaemia in the baby. To prevent this, an anti-D injection is given at week 28 to every Rh-negative pregnant woman, after any bleeding, miscarriage or injury to the abdomen, and within 72 hours of delivery. If antibodies have formed, mother and baby are monitored closely.
Many pregnant women carry antibodies that react to antigens found on the surface of red blood cells. When present, these antibodies can affect the wellbeing of both mother and baby during pregnancy. The good news is that with proper testing and timely care, most risks can be well managed.
How do these antibodies form in a woman’s body?
They develop when the immune system is exposed to factors that trigger antibody production, such as:
- A blood transfusion containing these antigens
- A pregnancy where the fetus carries these antigens on its red blood cells, allowing some of the baby’s blood cells to mix with the mother’s blood — often due to bleeding or miscarriage
How can these antibodies affect the mother?
They may make it harder to find matching blood units if she ever needs a blood transfusion.
How can these antibodies affect the baby?
They can cross the placenta and break down the fetus’s red blood cells, leading to fetal anemia. In more serious cases, this can cause heart strain, fluid buildup in the baby’s body, and sadly, can even threaten the baby’s survival in the womb if left untreated.
What is the most common antigen responsible for this issue?
The Rhesus (Rh) factor.
How are these antibodies checked during pregnancy?
- Testing the mother’s blood type early in pregnancy and again around the 28th week
- Screening for antibodies in the mother’s blood at the same two points in pregnancy
What can be done to prevent antibodies from forming if the mother is Rh-negative and the father is Rh-positive?
1- Giving the Anti-D injection whenever an event occurs during pregnancy that could trigger antibody formation, such as:
- Bleeding or miscarriage after 12 weeks of pregnancy (before 12 weeks, anti-D is needed only if the miscarriage is treated with surgery or medication, or the bleeding is heavy or painful)
- Abdominal trauma
- Surgery related to miscarriage or ectopic pregnancy
Procedures such as amniocentesis, chorionic villus sampling (CVS), turning a breech baby (external cephalic version), or termination of pregnancy
- As a routine preventive dose at 28 weeks for all eligible pregnant women
Where available, a simple blood test from the mother (cell-free fetal DNA) can show whether the baby is Rh-negative; if so, the routine anti-D injections are not needed
- Within 72 hours after birth if the baby’s blood group is Rh-positive, with a blood test (Kleihauer) to check whether an extra dose is needed; if 72 hours have passed, it can still be given up to 10 days after birth
3- Making sure any blood transfused to the mother is fully compatible with her blood type and free of antigens she doesn’t have.
How is pregnancy managed if these antibodies are found in the mother’s blood?
Antibody levels are checked periodically to make sure they don’t rise to a level that could affect the baby.
What happens if antibody levels become high enough to reach the baby?
The baby is monitored regularly with ultrasound to check for signs of anemia, including measuring blood flow patterns to the brain.
What if the baby does develop anemia?
Management depends on gestational age. If the pregnancy has reached 35 weeks or more, delivery is usually recommended, with blood transfusion given to the baby in the NICU if needed. If it’s still early in pregnancy, the baby may need blood transfusions performed inside the womb, repeated periodically until it’s safer to deliver.
Who monitors the baby for anemia and performs transfusions in the womb?
A maternal-fetal medicine specialist.
If you are pregnant and have questions about Rh factor testing, antibody screening, or the Anti-D injection, the team at Dr. Najeeb Layyous clinic is here to guide you through safe, personalized prenatal care.
Dr Najeeb Layyous F.R.C.O.G
Consultant Obstetrician, Gynecologist and Infertility Specialist
The finest doctor in Jordan — may God bless him and his whole medical team. A doctor in every sense of the word. I advise anyone planning a pregnancy to visit Dr. Najeeb Layyous. His manner is wonderful, always smiling, with the highest ethics; he gives every patient her due, and the patient’s comfort matters most to him. We had been to many doctors and none understood and treated my case except him. Special thanks to him and the whole team, and to Dina in particular — a lovely person. I recommend anyone considering IVF or pregnancy to visit his clinic.