Haemolytic Disease of the Newborn (HDN)

Protection for the Baby

Nowadays, Doctors, Nurses and Midwives are very aware of the problems that may occur when an RhD-Negative mother is carrying an RhD-Positive baby and they can act to prevent any problems occurring before the baby comes to any harm. In May 2002 the National Institute for Clinical Excellence (NICE)1 released recommendations regarding Anti-D prophylaxis. Anti-D prophylaxis means giving anti-D immunoglobulin to prevent a woman producing antibodies against RhD-positive blood cells and so to prevent the development of HDN in an unborn baby.

1. During Pregnancy
When an RhD-Negative mother is pregnant, the hospital staff can inject a small amount of ready-made RhD antibodies at weeks 28 and 34 of pregnancy. Then, if any of the baby’s RhD-Positive blood were to enter the other’s blood system during pregnancy, the injected antibodies would be there ready to remove the RhD Factor immediately. This injection is often referred to by medical staff as ‘Anti-D’. Anti-D immunoglobulin is made from a part of the blood called plasma that is collected from donors. The production of anti-D immunoglobulin is very strictly controlled to ensure that the chance of a known virus being passed from the donor to the person receiving the anti-D immunoglobulin is very low- it has been estimated to be 1 in 10,000 billion doses.

2. After Childbirth
Hospital staff will test the baby’s blood after birth. If the baby is found to be RhD-Positive, then the RhD Negative mother will be given another injection of Anti-D just in case any of the baby’s blood has passed across the placenta just before birth. This injection will remove any RhD-Positive red cells from the baby that may be in the mothers’ blood system. If a mother who has had these injections of Anti-D gets pregnant again, there will be no danger to her baby since her own immune system has not produced Anti-RhD antibodies, which might cross over and harm her unborn child.

3. Incidents During Pregnancy
Sometimes an RhD-Negative pregnant woman may need to be given Anti-D if there has been an incident during pregnancy that may have caused a small bleed from the unborn baby into the mother’s circulation - for example; seat-belt injury or vaginal bleeding. It is important that the mother reports any such incident to her midwife as soon as it happens.

Reference: 1. National Institute for Clinical Excellence (2002). Guidance on the use of routine anti-D prophylaxis for RhD-negative women. NICE Technology Appraisal Guidance No. 7. London: National Institute for Clinical Excellence. Available from www.nice.org.uk

Please contact your GP or Midwife, for further information about the RhD Factor and what it means to you.