If you found out at your booking appointment with your midwife that you’re rhesus negative, this is what it means.
Rhesus negative: what it means
You’ll have a test for your blood group (A, B, AB or O) in your initial booking in appointment. The blood test will also show if you’re rhesus positive (RhD-positive) or rhesus negative (RhD-negative).
About 15% of the UK population are rhesus negative and 17% of all births in England and Wales are to rhesus negative women (NICE, 2008). In about 10% of all births in England and Wales, the mum is RhD-negative and the baby has inherited RhD-positive blood from the dad (NICE, 2008). And that’s where things get a bit complicated…
Rhesus negative: issues for the baby
Being rhesus negative is not a problem in your first pregnancy. But if you have more babies, you might need extra care.
If you are rhesus negative but have a rhesus positive baby, the baby’s blood can enter your bloodstream. The danger of that is that your immune system can develop antibodies against it that then attack the baby’s red blood cells. This is known as sensitisation.
Your baby’s blood can transfer to you during birth, or if you have a bleed, an injury like a fall or a car accident, or an invasive medical procedure (NHS, 2018). It might also happen after a previous miscarriage or ectopic pregnancy, or very rarely during a blood transfusion (NHS, 2018).
If that happens, the baby may get rhesus disease or haemolytic disease of the foetus and newborn (HDFN). That can result in anaemia and jaundice in the baby (NHS, 2018).
Rhesus negative: issues for the mum
Unfortunately, there’s no standard way of knowing whether your baby is rhesus-positive as testing is expensive and doesn’t happen as standard in the UK (Hawk et al, 2013).
If you’re rhesus negative and your partner is rhesus positive, you might be offered a couple of extra midwife appointments for ‘anti-D’ injections. While the evidence about the benefits of this approach isn’t conclusive, NICE recommends routine anti-D injections for all pregnant RhD-negative women in case sensitisation occurs (NICE, 2008; McBain et al, 2015). You can have anti-D either as a one-off dose at 28 to 30 weeks or as two doses at 28 and 34 weeks (NHS, 2018).
Anti-D is a blood product that can mop up rhesus positive antigens (NHS, 2018). It’s up to you if you want to take the injections though.
After the baby has been born, their blood will be checked to see whether it is RhD-positive. If it is, and you aren’t immune, you’ll be offered another anti-D injection (NHS, 2018).
Babies with rhesus disease: treatment
Around half of all cases of rhesus disease need barely any treatment, with the baby simply being monitored regularly during pregnancy (NHS, 2018).
Rarely, the baby may need a blood transfusion while they’re in the womb (NHS, 2018). Others may be need to be born early so that they can have treatments. These treatments might include phototherapy (light therapy), sometimes intravenous antibodies from healthy donors and rarely a blood transfusion (NHS, 2018).
This page was last reviewed in May 2018.
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Hawk AF. (2013) Costs and clinical outcomes of noninvasive fetal rhd typing for targeted prophylaxis. Obstetrics and Gynecology. 122(3):579-585. Available from: https://www.ncbi.nlm.nih.gov/pubmed/23921866 [Accessed 21st May 2018]
McBain RD, Crowther CA, Middleton P. (2015) Anti-D administration in pregnancy for preventing Rhesus alloimmunisation. Cochrane Database of Systematic Review. (9):CD000020. https://www.cochranelibrary.com/cdsr/doi/10.1002/14651858.CD000020.pub3…. [Accessed 21st May 2018]
NHS Choices. (2017) Blood groups. Available from: https://www.nhs.uk/conditions/blood-groups/ [Accessed 21st May 2018]
NHS Choices (2018) Rhesus disease. Available from: https://www.nhs.uk/conditions/rhesus-disease/ [Accessed 21st May 2018]
NICE. (2008) Antenatal care for uncomplicated pregnancies. Available from: https://www.nice.org.uk/guidance/cg62 [Accessed 21st May 2018]