Antenatal or Postnatal Anti-D?

[Homebirthmama]

Dear Mums,

I wonder if you can help answer this question, as no one in my midwife team seems to have an answer and it’s virtually impossible to find a clear and evidenced answer online:

I’m Rh Negative and my baby ( due date 13 December) is Rh Positive. I found this out via a blood test and I was given and Anti-D injection at 28weeks to avoid risk of sensitization during the pregnancy.

The guideline says that the injections protects you for 6 weeks and that I need to have another anti-D injection no longer than 72h after the birth.

My question is this: can I have an injections now ( 38weeks) instead of one after the birth?

Reason : I’m having the baby at home, and I would rather not travel to the hospital straight after he is born to have the injection. If the injections protects you from sensitization before the risk of our bloods mixing ( in this case during the birth) can’t I have the injection now instead of waiting for the sensitization to happen?

Thank you for your help!

We're just giving this thread a bump for you, OP, in case anyone's around to answer your query.

I'm pretty sure the answer is no because of the risk of a large fetal- maternal haemorrhage during labour and delivery. Have you asked if the homebirth team could facilitate giving it to you at home? You may have to go to the hospital at some point anyway for hearing screening for baby, in which case you could get it done then (as long as within 72 hours)

If your MW isn't able to answer the question, they will be able to discuss it with an obstetrician (there must be locally agreed protocols which will include the rationale behind their standard management). IIRC though it's normally offered post-delivery because a) screening the baby's blood isn't 100% accurate - they test again after delivery and if it turns out they're actually negative then you don't need it, b) if the baby is positive and there's evidence of a large feto-maternal haemorrhage at delivery then the dosing of the post-delivery injection may be different and need more testing (and you never know that a delivery is going to be straightforward until after it was straightforward).

@Where2GoNext thank you for your reply! Unfortunately they don’t give it the anti-D outside the hospital because it’s a blood product. However the hearing screening can be done at home.

From the systemic reviews out there seems that you are right, the reason they give it postnatal is because of the variable in hemorrhage in women giving birth, which would require different doses of anti-d..and without knowing how much a woman will bleed during birth, they don’t want to use more immunoglobulin than needed. This leads to the standard of giving the anti-d after the birth, even though current research shows that prenatal anti-d is more effective than the one given after the birth once sensitization has already happened.

So bottom line is that it would be more effective to have it before the birth, but it’s more practical for the NHS to give it afterwards.

Does this sound right to you too?

@Greybeardy thank you so much for your reply!

I was trying to find some evidence on the accuracy of the baby blood test via maternal blood ( I have done it around 26 weeks). As far as I can see from available research, the accuracy of that test is 99%, so pretty much certain. Did you find any other information that shows it’s not actually certain and could end up be a false positive ?

about 2% of babies for whom the antenatal test suggests they're RhD positive will turn out to be negative on testing at delivery. (The incidence of false negatives is much lower).