9 things you might not know about Anti-D…

Over the years, I’ve become aware that there are a few things that people are sometimes surprised to learn when I speak about Anti-D. I made sure to include all of these and loads more when I wrote my book Anti-D Explained. But I’m sharing a few of the most important ones here as well.


1. It’s made from blood…

Actually, most of the people who need to give Anti-D or consider whether they want to receive Anti-D do know this now. Not all, but most.

But this has changed in the time since I first became interested in this topic.

Previously, there was a real lack of awareness that Anti-D was manufactured from human blood.

This lack of awareness poses a real threat to women being able to make an informed choice. While people often question the need for a blood transfusion, they rarely question the need for Anti-D. That begs the question of whether they really know what they are being offered.

Most women want Anti-D anyway. But everyone has a right to know exactly what they are being offered.


2. It works more effectively than the vast majority of drugs used in maternity care…

Sara explains the issues and evidence, answers key questions and shares information about what we do and do not know about Anti-D and related topics from research evidence and current thinking. A vital resource for parents, professionals and birth workers.

I think this is an important one to note near the top as well. In the past, I was sometimes misquoted as saying women should decline Anti-D or that Anti-D doesn’t work.

Au contraire.

Postnatal Anti-D is incredibly effective. Although the evidence on routine antenatal Anti-D is, according to the Cochrane review in this area, of low to very low quality. So that’s another story.

What’s most important to me is that everyone has good information and makes the decision that’s right for them.

But when you look into the issues, it’s more complex than the simplified information leaflets would have you believe. There are risks and downsides, paradoxes and wider issues. It’s complicated. That’s why I write about topics like Anti-D in depth. These are big decisions. They deserve our time and attention.


3. We can speculate a bit about who may be at greater or lesser risk, though…

While the evidence is either indirect (in this case extrapolated from studies of related areas) or anecdotal/experiential and based on the observations and experiences of midwives, doctors, women and families, it would appear that less may be more when it comes to interventions. 

There is a theory that anything that could interfere with the integrity of the placental site – be it of pharmaceutical origin or related to manual interference such as fundal fiddling or early cord clamping or technological interventions like ultrasound – may increase the likelihood of fetal blood entering the maternal bloodstream. 

But there are no guarantees. Again, it’s complicated. Some women who have become isoimmunised after gentle, natural, unmedicated birth. And there’s a bigger picture to consider.

More on this in my book as well.


4. It was chosen by Time magazine as one of the top ten medical achievements of the 1960s…

And rightly so, as it has helped many babies. Although improvements in neonatal care have played an important role as well.

What some people find problematic is the assumption that, because Anti-D works to prevent a serious problem that would occur in a proportion of women, there is no need to do further work to determine which women would become sensitised without it and which women would be fine. 

Many of the women in the original clinical trials didn’t become sensitised. Anti-D is a blood product with attendant risks. So it is frustrating that we don’t have more research. All we can tell women is that it is not a given that they will become sensitised if they decline Anti-D. And that research to determine who does and does not need it has never been a priority. Neither has research been carried out into alternatives.


5. The question of who benefits from it leads to quite a mind-bending paradox…

Anti-D is the only drug/medicine that I know (but let me know if you can think of another) where the following things are true:

It is administered to a person (the pregnant or postnatal woman) whom it does not directly physically benefit, but who has to accept the risk of possible side effects from it. 

When it is given in pregnancy, it is given to the possible detriment not only of the person to whom it is administered (the woman) but also another person (the baby in utero) who does not directly benefit from it. 

This is because it is given for the possible benefit of a future person or people – any children the woman may have after her current pregnancy – who do not yet exist and may never exist.

Not that this negates the value of Anti-D, but it’s something to ponder…


6. The Kleihauer test is not a screening test for fetomaternal haemorrhage…

It is a screening test for larger-than-normal fetomaternal haemorrhage. And ‘normal’ in this context describes the 4ml of fetal blood whose effects will be cleared by the standard dose of Anti-D given in most countries. 

This is a really important distinction. 

If a woman has a negative Kleihauer test, it does not imply that there is no fetal blood in her circulation. 

There may be no fetal blood in her circulation, but the Kleihauer test isn’t sensitive enough to tell us that. Scientific and laboratory officers expect to not see fetal blood on a Kleihauer test

All that a negative Kleihauer test can tell us is that no fetal blood can be seen. This is taken to imply that, if there is a little fetal blood in the woman’s circulation, this is likely to be an amount whose effects can be cleared by a standard dose of Anti-D.

If a Kleihauer test is positive and a woman’s baby is rhesus positive then she will almost certainly end up being offered additional doses of Anti-D. That’s in order to clear the additional fetal blood that is in her circulation.


7. Because of this, there may be little value giving Anti-D without doing a Kleihauer test…

Some people in rural areas work with no lab access or have other resource issues. In that situation, they may have no choice but the offer Anti-D without Kleihauer testing. In all other situations where Anti-D is given because there has been a potentially sensitising event, a Kleihauer test should also be offered.

Although larger-than-normal bleeds are unusual, they do occur. Women need to know that giving Anti-D is only half the story. We also need to offer them a test that tells us whether we have given enough. Otherwise, we can end up with a woman who chooses to have Anti-D and yet has still become sensitised.


8. Because Anti-D is made from blood, it should be afforded the same respect and precautions that we afford a blood transfusion…

This means appropriate monitoring of vital signs. It also means access to immediate help and treatment should anaphylaxis ensue. This is where things get controversial again. I don’t want women who have out-of-hospital births to have to leave the sanctity of their environment simply to receive Anti-D. But in some areas it is not given at home or in the community. It’s worth asking about what will happen locally if you’re planning home birth.


9. We might not need to offer Anti-D routinely in pregnancy if the current guidelines were followed…

Sara explains the issues and evidence, answers key questions and shares information about what we do and do not know about Anti-D and related topics from research evidence and current thinking. A vital resource for parents, professionals and birth workers.

You can read the full argument in my book. But the core of the issue is that we know that the Anti-D programme isn’t implemented effectively in all areas. 

We know about the problem of so-called ‘silent’ sensitisation. 

What we don’t know is how much of the so-called silent sensitisation is really silent. And how much of it is due to professional failure to offer Anti-D according to the current guidelines. Given that some women would prefer not to have intervention if they don’t need it, we have another situation where we desperately need more information.


If you’d like to know more about Anti-D, my book is called Anti-D Explained. It has been written to help women and families understand the issues and the evidence. You can also hear me talking about Anti-D on a podcast which is available here.
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