Rh incompatibility and anti-D: what to know if you are Rh negative

At your first visit your blood group and Rh factor are checked. If the result is Rh negative, there is no need to worry; it is very common and there is a well-known, effective way to look after it.

What is the Rh factor?

Rh is a protein that can be found on the surface of red blood cells. If you have it, your blood group is Rh positive; if not, it is Rh negative. It does not affect your own health and matters only during pregnancy.

When does Rh incompatibility happen?

Incompatibility means an Rh negative person is carrying an Rh positive baby. Your baby's blood usually does not mix with yours. But during birth, bleeding or certain procedures a small amount can cross over. The immune system may treat it as foreign and make antibodies.

These antibodies usually do not affect a first pregnancy. In a later Rh positive pregnancy, they could harm the baby's red blood cells. That is why prevention is planned from the start. The good news is that with proper follow-up and the preventive injection, this problem can largely be avoided, and serious cases have become far less common.

Which tests are done in pregnancy?

• Blood group and Rh: Determined at the first visit.
• Partner's Rh status: If your partner is also Rh negative, the baby is likely Rh negative too; your doctor takes this into account.
• Indirect Coombs test: Checks whether Rh antibodies have formed in your blood. According to the Turkish Ministry of Health guideline, a negative result is repeated later in pregnancy, around week 28.

What is an anti-D injection?

Anti-D immunoglobulin is an injection that helps prevent antibodies from forming. If you have no antibodies and the baby may be Rh positive, your doctor will offer it. In the Turkish Ministry of Health guideline this is a step at the third visit (weeks 28–32) when the indirect Coombs test is negative. Your doctor decides the exact time.

After birth, the baby's blood group is checked. If the baby is Rh positive, a second dose is given after birth, within the time your doctor sets. If the baby is Rh negative, this dose may not be needed.

Anti-D may also be needed if there is bleeding, a threatened miscarriage, an injury to the abdomen or a procedure such as amniocentesis. So it is important to tell any health facility that you are Rh negative.

What you can do

• Note down your blood group and mention it everywhere you get care.
• Ask for the date of each anti-D dose to be written in your record.
• The injection site can be sore for a few days; mild pain usually passes by itself.
• Bring your questions to the third visit: Do I have antibodies? When will the injection be? What happens after birth?
• Add a card with your blood group to your hospital bag checklist.

When to contact your doctor

• If you are Rh negative and have any vaginal bleeding during pregnancy
• If you have had a blow to the abdomen or a fall
• If you have severe abdominal pain that does not ease
• If your baby's movements clearly decrease
• If you get a reaction after the injection such as a rash, shortness of breath or facial swelling

For heavy bleeding or breathing difficulty call 112 (or your local emergency number). This article is for information; your doctor's advice for your own situation comes first.