Rhesus Negativity

All bloods types are either Rhesus Positive (e.g. A+, O+) or Rhesus Negative (e.g. A-, O-). If you’re Rhesus Positive, then this article doesn’t apply to you!

If you’re rhesus negative and this is your first baby, you’ll be offered something called Anti-D injections. Basically, if you are Rh- but your baby is Rh+, if the baby’s blood has mixed with yours during pregnancy or birth, your body may develop antibodies that attack the baby’s cells. This won’t have an impact on your first pregnancy, but if you develop these, it could cause problems for subsequent Rh+ babies’ pregnancies, as your body can react to the baby’s cells as “invaders”.

“When the birthing person is rhesus negative, they are offered blood tests right after birth.

One sample of blood comes from the baby’s cord to check the baby’s blood group.

If the baby is also negative, no further action is offered.

If the baby is positive, the other sample, from the mother, checks if any of the baby’s blood has mixed with the mother’s during birth.....depending on how much has mixed, a dose of anti D is offered (to stop sensitisation to the rhesus positive blood of the baby within the mother, which has the potential to affect future rhesus positive baby pregnancies).”

- Deborah Neiger, Independent Midwife

How are blood samples taken from baby?

Standard practice is usually that the umbilical cord is clamped and cut early, to draw “cord bloods”, however this can be avoided. Think about it ahead of time, discuss it with your care providers, and put it in your birth plan!

  • Bloods can be taken from placental surface vessels most of the time

  • Bloods can be taken from the umbilical vein without cutting the cord early, before the placenta is delivered

  • Bloods can be taken from baby

  • You can opt for none of the above, and just have your blood checked for mixing and receive Anti-D to be on the safe side (not a usual option; read Deborah Neiger’s article below for more information)

  • …or you can opt out of the whole thing, if that’s what you think it right for you and your family.

What happens if I do develop antibodies to my baby’s Rhesus Positive blood cells?

If this happens in your first pregnancy with a Rhesus Positive baby, and you do not receive Anti-D, in future pregnancies with a Rh+ baby you may develop something called Rhesus Disease.

“Rhesus disease is a condition where antibodies in a pregnant woman's blood destroy her baby's blood cells. It's also known as haemolytic disease of the foetus and newborn (HDFN).

Rhesus disease doesn't harm the mother, but it can cause the baby to become anaemic and develop newborn jaundice.” (NHS)

The links below give more information about your options, the pros and cons of Anti-D, and the risks and treatment of Rhesus Disease.

As ever, arm yourself with information from reliable, up-to-date sources, and make the choices that are right for you and your family.