What Evidence do we have that Evidence is Evidence Based? And What Should We Even Be Doing With It?

Emma Ashworth, Birth Activist and DD Specialist Companion
A blog by Emma Ashworth, Birth Activist and DD Specialist Companion. You can book sessions with Emma to pick her brain on all things human rights in childbirth or for support with specific situations your clients’ rights are not being respected.

NHS care prides itself on being evidence based – right? Yet, how often, in reality, are guidelines and policies actually based on evidence? 

And is this even the right question?

At the beginning of the pandemic, we all remember President Trump suggesting that America should stop testing for covid; that the only reason that the numbers were so high in the US were because they did so many tests. The logical fail of this statement made him a laughing stock – but what if this type of logic fail is happening all the time in research? What if maternity care is (at least partly) evidence based, but the evidence is actually pretty rubbish much of the time?

Pregnant women and people have the right to be given the evidence or information upon which recommendations about their care are based. A valuable skill for doulas is to be able to understand research and related work, to understand what it’s saying – and what it actually means. For instance, in the Trump example above, if he’d cancelled testing across the country he might have claimed that “there is no evidence that covid is spreading across the US.” Of course there’s no evidence if no evidence is being sought – even though covid was spreading like wildfire!

This leaves us to top tip one:

“There is no evidence that…” may mean that something has been disproven…
but it may also mean that no one has looked.

Take Vitamin K, for example. There is no evidence that giving Vitamin K to a neonate causes infertility. However, that’s because no studies have ever looked at whether there’s a relationship between Vitamin K and infertility. We simply don’t know, so there is no evidence. This is very, very different to this relationship being carefully studied, and the outcome of those studies stating that “there is no evidence of a connection”. 

If you’re told, “there’s no evidence that A causes B”, go ahead and ask what they mean. Has the issue been studied and the research shows that there is no link between A and B? Or has any possible relationship between A and B never actually been looked at?

Before I start an internet rumour, there is absolutely no suggestion that there is any link between Vitamin K and infertility! The example is a complete fabrication. But, the concept of an internet rumour leads us nicely into top tip two:

Received wisdom may have no basis in reality.

There are so many examples of this within maternity, but I’m going to share two important ones.

Routine episiotomies

The majority of our mothers and grandmothers will have been given an episiotomy during their births. Routine episiotomy became fashionable in the 1920s when an influential (male) obstetrician claimed that it was the best way to save women and babies from the “evil” of labour, which he called, “pathogenic”. It wasn’t until the 1980s and later that evidence-based medicine looked at the evidence of the outcomes of routine episiotomy, and found that very often they cause more harm than good. 1 Despite this, it took years for them to stop being routine, and there are still practitioners with much higher rates of episiotomies than other practitioners, without evidence of better outcomes, but more women and people with injured perineums.

Waterbirth and water embolism

Many waterbirth guidelines still state that women “should” get out of the pool to birth their placenta, due to the risk of water embolism.

There have never been any recorded cases of water embolism caused by birthing the placenta in water.

The reason this is even mentioned as a possibility is because waterbirth expert, midwife-obstetrician Michel Odent was once pushed very hard for a downside to these pool births that he’d been raving about. He said that – well – maybe – it might be possible – perhaps – for water embolism to occur if the placenta was born in water. He has since said, “I’m very sorry.” 2

Despite the fact that there’s no evidence for it, women and birthing people continue to be told that they’re “not allowed to” birth their placenta in the pool. We don’t need to accept this. What can we do to help our clients to advocate for themselves when it seems that the answers that we’re given are unreasonable or not based on evidence? This leads us to top tip three: 

Don’t take unreasonable answers for an answer!

In our workshop, “Consent: Rights in Childbirth”, we share a range of tools that help clients to navigate the maternity system. One of the most popular we call “Why, why, why?” but it might also be called “the dog with a bone” tool! It simply means that it’s important to keep asking “why?” and not to accept answers which don’t make sense. The example that we give in the workshop is about waterbirth and high BMI and it goes something like this:

Midwife, “You can’t have a pool birth because you are high risk”
Client, “What am I at high risk of?”
MW, “Well, you have a high BMI.”
Client, “How does having a high BMI affect me using the pool?”
MW, “Because you might be too heavy for us to lift out of the pool.”
Client, “But my BMI isn’t the same as my weight, and people can be heavier than me but with a lower BMI”
MW, “Well, either way, your weight is too high.”
Client, “What difference does my weight mean?”
MW, “Because the hoist doesn’t support your weight.”
Client, “Can you check that please?” – note that hospital hoists are designed for VERY heavy weights

Often, hospital birth pools don’t have hoists and in the very unlikely scenario of a mother or birthing person collapsing in the water without sufficient warning to allow her to safely leave beforehand, the hospital protocols describe a specific number of people being required to help to get her out. There is no reason why this protocol shouldn’t include sufficient people to support people of any weight. One’s weight does not affect your entitlement to pain relief. 

Common replies such as “because health and safety” or “because covid” or “because high risk” are not actually answers, and you and your clients have every right to have proper, complete and logical explanations. Often, when you start to ask people to really evaluate what they’re saying, they discover that their reasons are more for the convenience of the hospital, or are simply not based on evidence or equality. Keep asking why!

So – what about reading evidence? What if we’re presented with a study that tells us something that supports a doctor or midwife’s advice. Should we take this at face value?

My husband, who works with databases, says there’s a common phrase used around both databases and statistics which I’m going to call top tip four:

Garbage in, Garbage out.

If the trial is just run in a way which isn’t well designed (garbage in) you’ll not get an answer that is reliable (garbage out).

In healthcare, we consider randomised controlled trials to be the “gold standard” of evidence. Randomised controlled trials, or RCTs, usually compare an intervention or group of interventions with not doing those interventions. A group of people who don’t mind whether they have the intervention or not are split into two groups and randomly allocated to the group with the intervention, or the group without the intervention (the control group). If possible, the trial is blinded. This refers to whether or not the participants, experimenters and/or researchers know who is in which trial. For instance, if a new drug is being tested, the patient and experimenter might both be unaware whether they are taking/giving a placebo drug or the new drug, so they can’t make pre-judgements on its efficacy depending on what they expect to see. 

Unfortunately, it’s really hard to do properly-blinded RCTs in maternity, because it’s generally quite clear to the woman or birthing person whether or not they’re getting the intervention. It is more common to do research in other ways, which is explained in the AIMS Birth Information article, “Understanding quantitative research evidence”.3

Even if evidence comes from an RCT, it doesn’t mean it’s good evidence. Take the ‘Arrive’ trial for instance. 4 Even if you’ve not heard of this trial, if you’ve ever heard a doctor or midwife claiming that induction doesn’t increase the rate of caesarean, they are most likely referring to the Arrive trial. The outcomes looked at were perinatal death, severe neonatal complications and caesarean birth. On the face of it, Arrive looked at whether inducing early (at around 39 weeks) led to improvements in some outcomes than waiting until at least 40 weeks and 5 days. However, many of those women allocated to “expectant management” (not be induced) were still induced, just a couple of weeks later. Therefore, the Arrive trial does not actually compare being induced at 39 weeks with not being induced, contrary to what is often claimed. 

Women in the early induction group had around a 19% chance of a caesarean, compared to 22% in the supposed non-induction group, which seems to show that inducing earlier reduces the caesarean rate. But is this really true?

Firstly, this data does not show that inductions do not increase the chance of having a caesarean. Remember that in the group that is often considered to be the non-induction group, many women were in fact induced, so it was not possible to conclude that inductions reduce the chance of a caesarean. 

Secondly, there are concerns that due to the way that the trial was performed, it’s possible that in the expectant management group, there might have been a lower threshold to make the decision to move to a caesarean than in the induced group. This is clearly explained in this excellent article by Henci Goer5. Garbage in, garbage out? 

If you don’t feel confident in reading research yourself, you may find that there’s an evaluation of it in the AIMS Journal, or elsewhere on the Internet so have a search around and see what you find.

Research is often evaluated by the Cochrane Library. Cochrane is an organisation which looks at research, evaluates how good they are and summarises a group of research papers into one document. This is usually really helpful when you don’t want to read through half a dozen pieces of research on a topic, but want a reliable summary. Which brings us to our penultimate tip – top tip five:

The Cochrane Library is generally a reliable source of explanations of research data.

Cockrane usually has two versions of its reports. One contains all the details of the research that they looked at, together with detailed descriptions of how they’ve evaluated the research and the statistics. The other is a lay person’s review which is accessible to all, and summarises their findings in clear language. If you’re looking for information on a topic, this is a great place to start.

While in many ways it’s been hugely valuable to move towards an evidence based maternity system, being “evidence-based” isn’t always as black and white as it really should be. We find ourselves swimming around in data – some garbage – some good – and even good data can be poorly used. 

It’s always important to remember that you can question everything! One piece of research may appear to come to one conclusion, but do others agree? Organisations such as Cockrane have made it much easier for us to find out. 

But in the end, while evidence is helpful, not matter what it says, it doesn’t override our personal decisions and rights. Which brings me to our final, sixth top tip: 

Evidence doesn’t Trump our Rights

The evidence might show that we may be at higher risk of a post partum haemorrhage, or shoulder dystocia, or tearing. That doesn’t mean we don’t have the right to access care that’s right for us, such as a birth pool, midwifery led unit or home birth. Remember that evidence looks at what interventions – or lack of interventions – might benefit a certain number of women and people in a group. It’s vanishingly rare that whatever is researched is going to be right for everyone. There can also be evidence that is somewhat contradictory, leading to “the right answer” being really tricky to work out. For instance, we know that birth positions on our back make shoulder dystocia more likely, whereas free movement makes them less likely6. We know that labouring and birthing in a pool makes free movement easier. Therefore, while dealing with a shoulder dystocia that is recognised in the pool might be trickier than on dry land, being in the pool is likely to reduce the chance of it happening in the first place.

We can use evidence in this way to help us to negotiate the pregnancy, birth and postnatal experience that we want. We don’t need to accept that because a piece of research says one thing, we have to follow that pathway, and we can use evidence to support our position, even if it conflicts with other research. 

We are lucky to live in an age of research and evidence, but knowing its limitations is as important as being able to interpret it. I hope that this article has helped you to better understand research and evidence, and you and your clients can use it to assert your rights and get the birth they want.
If you would like to explore rights in pregnancy and birth further, join Maddie, Verina and me in our workshop, “Consent: Rights in Childbirth
Find me on Instagram at / or book a consultation with me – https://linktr.ee/emma_ashworth

A brief history of vaginal cutting during childbirth: https://gizmodo.com/a-brief-history-of-vaginal-cutting-during-childbirth-1710537581
The Theoretical risk of water embolism: https://www.sarawickham.com/articles-2/the-theoretical-risk-of-water-embolism/
“Understanding Quantitative Research Evidence” by AIMS: https://www.aims.org.uk/information/item/quantitative-research
“Labor Induction versus Expectant Management in Low-Risk Nulliparous Women”: https://www.nejm.org/doi/full/10.1056/NEJMoa1800566
Parsing the ARRIVE trial: https://www.lamaze.org/Connecting-the-Dots/parsing-the-arrive-trial-should-first-time-parents-be-routinely-induced-at-39-weeks
Midwife Thinking: Shoulder Dystocia – the real story: https://midwifethinking.com/2015/05/13/shoulder-dystocia-the-real-story/

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