Treatment for rhesus disease depends on how severe the condition is. In more severe cases, treatment may need to begin before the baby is born.

Around half of all cases of rhesus disease are mild and don't usually require much treatment. However, your baby will need to be monitored regularly, in case serious problems develop.

In more severe cases, a treatment called phototherapy is usually needed and blood transfusions may help to speed up the removal of bilirubin (a substance created when red blood cells break down) from the body.

In the most serious cases, a blood transfusion may be carried out while your baby is still in the womb and a medication called intravenous immunoglobulin may be used when they're born if phototherapy isn't effective.

If necessary, the baby may be delivered early using medication to start inducing labour (induction) or a caesarean section, so treatment can start as soon as possible. This is usually only done after about 34 weeks of pregnancy.

Phototherapy is treatment with light. It involves placing the newborn baby under a halogen or fluorescent lamp with their eyes covered.

Alternatively, they may be placed on a blanket containing optical fibres through which light travels and shines onto the baby's back (fibre optic phototherapy).

The light absorbed by the skin during phototherapy lowers the bilirubin levels in the baby's blood through a process called photo-oxidation. This means that oxygen is added to the bilirubin, which helps it to dissolve in water. This makes it easier for the baby's liver to break down the bilirubin and remove it from the blood.

During phototherapy, fluids will usually be given into a vein (intravenous hydration) because more water is lost through your baby's skin and more urine is produced as the bilirubin is expelled.

Using phototherapy can sometimes reduce the need for a blood transfusion.

In some cases, the levels of bilirubin in the blood may be high enough to require one or more blood transfusions.

During a blood transfusion, some of your baby's blood is removed and replaced with blood from a suitable matching donor (someone with the same blood group). A blood transfusion normally takes place through a tube inserted into a vein (intravenous cannula). 

This process helps to remove some of the bilirubin in the baby's blood and also removes the antibodies that cause rhesus disease.

It's also possible for the baby to have a transfusion of just red blood cells to top up those they already have.

If your baby develops rhesus disease while still in the womb, they may need to be given a blood transfusion before birth. This is known as intrauterine foetal blood transfusion.

An intrauterine foetal blood transfusion requires specialist training and is not available in all hospitals. You may therefore be referred to a different hospital for the procedure.

A needle is usually inserted through the mother's abdomen (tummy) and into the umbilical cord, so donated blood can be injected into the baby. An ultrasound scan is used to help guide the needle to the right place.

Local anaesthetic is used to numb the area, but you'll be awake during the procedure. A sedative may be given to keep you relaxed and your baby may also be sedated to help stop them moving during the procedure.

You may need more than one intrauterine foetal blood transfusion. Transfusions can be repeated every 2 to 4 weeks until your baby is mature enough to be delivered. They may even reduce the need for phototherapy after birth, but further blood transfusions could still be necessary.

There's a small risk of miscarriage during an intrauterine foetal blood transfusion, so it's usually only used in particularly severe cases.

In some cases, treatment with intravenous immunoglobulin (IVIG) is used alongside phototherapy if the level of bilirubin in your baby's blood continues to rise at an hourly rate.

The immunoglobulin is a solution of antibodies (proteins produced by the immune system to fight against disease-carrying organisms) taken from healthy donors. Intravenous means that it's injected into a vein.

Intravenous immunoglobulin helps to prevent red blood cells being destroyed, so the level of bilirubin in your baby's blood will stop rising. It also reduces the need for a blood transfusion.

However, it does carry some small risks. It's possible that your baby may have an allergic reaction (anaphylaxis) to the immunoglobulin, although it's difficult to calculate how likely this is or how severe the reaction will be.

Concerns over possible side effects, and the limited supply of intravenous immunoglobulin, mean that it's only used when the bilirubin level is rising rapidly, despite phototherapy sessions.

Intravenous immunoglobulin has also been used during pregnancy, in particularly severe cases of rhesus disease, as it can delay the need for treatment with intrauterine foetal blood transfusions.