I have antibodies in my pregnancy

Red cell antibodies in pregnancy

Introduction

During your pregnancy you will have been offered blood tests to check your blood group and also to find if you have any antibodies to red blood cells. These tests are usually carried out at the booking visit and again at 28- 30 weeks. This leaflet explains why blood groups and antibodies are important in pregnancy. It also contains details about how and why we monitor your pregnancy if we identify you to have red cell antibodies.

What are blood groups?

Red blood cells are cells in the blood stream which carry oxygen around the body. The red cells have natural molecules on the surface which make up your blood groups. Your blood group is determined by the genes you inherit from your parents. There are several different types of blood groups, with the four main ones being A, B, AB and O. Each of the blood groups can be either RhD positive or negative. There are minor blood groups that make up your overall blood group when tested, that can be important if you develop antibodies against these such as ‘c’ (little c) and ‘K’(kell), although there are many minor ones that cause no concerns for your pregnancy.

What are red cell antibodies?

Antibodies are the body’s natural defence against anything which is different from you, such as a virus, a vaccine or a different blood group. This is part of your normal immune system to protect your body.

You may develop antibodies if blood cells with a different blood group from your own enter your blood stream. This can happen if you have a blood transfusion or during pregnancy.

How are these antibodies made during pregnancy?

A few of your baby’s blood cells may ‘leak’ into your blood stream during pregnancy.

This can happen if:

• there has been any bleeding in pregnancy
• trauma to the abdomen such as a car seat belt injury or a fall
• If there has been an invasive procedures such as CVS or Amniocentesis in pregnancy
• Or more commonly when giving birth, the mother is exposed to her baby’s blood during delivery.

If your baby’s blood group is different from your own, your immune system may produce antibodies. This is uncommon, affecting about three in a hundred pregnancies. Most of the time, this process will be harmless to mother and baby.

Will these antibodies affect my baby?

It is rare for antibodies to cause significant problems for your baby; however problems may arise if they cross the placenta and affect the baby’s red blood cells. In most cases the baby is not harmed, however certain antibodies, particularly if they are present in high levels, can destroy your baby’s red blood cells. If this occurs your baby can become anaemic. Prior to birth this is called fetal anaemia and after birth it is called Haemolytic Disease of the Newborn and causes jaundice.

What happens if I have developed antibodies in my blood?

If blood tests show that you have developed antibodies that may affect the baby, you may need additional checks. You will be offered further blood tests to measure the levels throughout your pregnancy. How often you have blood tests will depend on which antibody you have developed. Some pregnancies will need regular monitoring with ultrasound scans but most of the time no treatment is needed.

If your antibody levels rise above a certain level, your baby may need to be delivered early. Your consultant will discuss this with you if this is necessary.

Is it possible to check my baby’s blood group?

Before checking the baby’s blood group it is helpful to take a blood sample from the father of the baby. This result will show two possibilities either that

• Your antibodies will definitely have the potential to affect your baby’s blood cells.
• There is a 50% chance of potentially affecting your baby’s blood cells.

Your doctor will explain to you if it is possible to check your baby’s blood group by taking a blood test from you.

This test is possible because genetic information (DNA) from your unborn baby can be found in your blood. In the majority of cases it is possible to get a reliable result, however occasionally we have to repeat the test if there is not enough of your baby’s DNA in your blood sample and rarely we may fail to get a result.

What happens if my antibodies are a risk for my baby?

Based on the blood tests we have taken we may suggest monitoring your pregnancy in our fetal medicine clinic as a precaution to ensure the wellbeing of your baby. Your consultant will explain how often you need to attend for appointments.

Performing an ultrasound scan will allow us to measure how quickly blood flows through a blood vessel in the baby’s brain. Babies who are anaemic usually have thinner blood and the blood flows quicker when measured on a scan. Babies that are severely anaemic can also have extra fluid under their skin and on the inside of their bodies (hydrops). We would check for these findings on the scan.

What happens if my baby is suspected to be anaemic?

If the information obtained from ultrasound scans suggests that your baby is anaemic there are two options:

1. Delivering your baby so the neonatal team can help (we would suggest this if the baby was 34 weeks gestation or more).
2. Performing a procedure in the womb to confirm your baby’s blood count.

This procedure involves inserting a fine needle through your abdomen to take a small blood sample from your baby. If your baby is confirmed to be anaemic, we would go straight on to perform a blood transfusion (Intra Uterine Blood Transfusion) through the same needle. There is a small chance of complications with this procedure and therefore would only carry this out if this is necessary. It is likely that we would perform IUT’s every 2-4 weeks until your baby is mature enough to be delivered.

What treatment may my baby need?

Blood will be taken your baby’s umbilical cord when they are born to check for anaemia and jaundice. Jaundice is caused by a build of a chemical in the blood called bilirubin and causes the baby’s skin and whites of the eyes to turn yellow. If there are high levels of bilirubin the baby may be at risk of deafness, blindness and brain damage without prompt treatment.

Phototherapy is treatment with light. This involves using a blanket or a soft fibre optic suit where light travels directly onto the baby’s skin. The light is absorbed and lowers the bilirubin levels. Regular blood tests will be taken in the hospital to check this.

In some cases the bilirubin in the blood may be high enough for your baby to need treatment with a blood transfusion, however having phototherapy may reduce this risk.

For further information

For further information please contact:

Fetal Medicine Department,
Royal Victoria Infirmary
(0191) 2825837
Monday –Friday 9-5pm

Be sure to ask questions to the doctor supplying you with this leaflet and make a note of any questions you would like to ask at your next Fetal Medicine Unit appointment.

Antenatal Results and Choices
0845 077 2290 or 0207 713 7486 via mobile

North of Tyne Patient Advice and Liaison Service (PALS)
0800 0320202
Monday to Friday 9.00-4.30pm (answer phone out of hours)
Email: [email protected]