In some pregnancies there may be a mismatch between the mother’s and the foetus’s blood, known as Rh incompatibility. It’s essential to understand and address this condition, to ensure a smooth and healthy pregnancy.
This article explores what Rh incompatibility is and what it can mean during pregnancy and after childbirth, in terms of testing and therapeutic measures.
The RhD (Rhesus D) factor is a molecule found on the surface of red blood cells. The two RhD types are RhD-positive (with the molecule) and RhD-negative (without the molecule). Rh incompatibility can occur when an RhD-negative mother is carrying an RhD-positive baby.
In most pregnancies, the mother and baby don’t share blood. However, there is a risk that small amounts of their blood could mix during childbirth, or in other situations like injury or vaginal bleeding.
Rh incompatibility can lead to a condition called Rh sensitisation or Rhesus disease. If the mother’s blood does come into contact with the unborn baby’s, the mother’s immune system produces antibodies that attack the baby’s red blood cells. While this may not affect the first baby, it can pose a risk to future pregnancies with RhD-positive babies.
Blood-type and foetal DNA testing
During early prenatal care, healthcare providers check the blood type of pregnant women, specifically for the presence or absence of the RhD factor.
Some hospitals provide RhD screening by analysing foetal DNA in the mother’s plasma cells. This method can be especially beneficial for women carrying a foetus with a negative blood group, as it eliminates the need for immunoglobulin injections (see below).
Anti-D immunoglobulin injections
To prevent Rh sensitisation, RhD-negative pregnant women are typically given an anti-D immunoglobulin injection around the 28th week of pregnancy. This injection helps prevent the mother’s immune system from producing antibodies against RhD-positive blood cells.
Post-birth injections of anti-D immunoglobulin
After delivery of the baby, a blood sample will be taken from the placental cord and checked for the baby’s blood group and rhesus status. If the baby is RhD-positive, an additional anti-D immunoglobulin injection is given to the mother within 72 hours of childbirth. This is also recommended in the case of any potential exposure to the baby’s blood during pregnancy.
Monitoring Rh sensitisation
Regular monitoring may be required during subsequent pregnancies to assess for signs of Rh sensitisation. In severe cases, interventions such as intrauterine blood transfusions may be necessary.
Collaboration with healthcare professionals
Rh incompatibility emphasises why it’s so important to communicate with your healthcare team. Regular prenatal check-ups and discussions about blood type and RhD factors are crucial for timely interventions and a healthy pregnancy.
