Episode 29 Big baby

Why does it seem like we are offering induction to more women for a big baby? Are babies getting bigger ? What drives us to offer intervention?

If you want to know more detail about the topics discussed in this episode these links may help:
 https://www.nice.org.uk/guidance/ng121/evidence/evidence-review-q-largeforgestationalage-baby-pdf-241806242780

Fetal growth surveillance current guidelines practice and challenges https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6042298/ 

Montgomery ruling
 https://www.rcog.org.uk/globalassets/documents/members/membership-news/og-magazine/december-2016/montgomery.pdf
Cochrane info graphic
https://pregnancy.cochrane.org/sites/pregnancy.cochrane.org/files/public/uploads/induction-for-macrosomia%20%28screen%29.pdf 

https://warwick.ac.uk/fac/sci/med/research/ctu/trials/bigbaby

a mother’s perspective http://matexp.org.uk/the-matexp-journey/i-was-told-i-was-going-to-have-a-big-baby-and-then-what-happened/

You can find out more about me on Twitter @FWmaternity & @TheObsPod please check out #MatExp matexp.org.uk for ideas about how to improve maternity experience.

My beautiful artwork is thank to Anna Geyer www.newpossibilities.co.uk

Thank you all for listening, My name is Florence Wilcock I am an NHS doctor working as an obstetrician, specialising in the care of both mother and baby during pregnancy and birth. If you have enjoyed my podcast please do continue to subscribe, rate, review and recommend my podcast on your podcast provider.
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Transcript

Episode 29 Big Baby

Florence Wilcock: [00:00:00] Hello, my name's Florence. Welcome to the obs Pod. I'm an NHS obstetrician hoping to share some thoughts and experiences about my working life. Perhaps you enjoy, call the midwife, maybe birth fascinates you, or you'll simply curious about what exactly an obstetrician is. You might be pregnant and preparing for birth.

Perhaps you work in maternity and want to know what makes your obstetric colleagues tick or you want some fresh ideas and inspiration, whichever of these is the case. And for that matter, anyone else that's interested? TheobsPod is for you.

Episode 29, big Baby. Today I'm going to talk about large for dates or big babies. Recent threads on Twitter, [00:01:00] highlight anecdotal evidence that inductions and interventions for so-called large for dates, babies are on the up. Seeing this on Twitter made me think that this would be a good topic to talk about on the obspod, and indeed when I tweeted that I got a positive response from some of the midwives and women discussing it.

It's not a new topic. In fact, five years ago when I started my work in maternity experience, Helen Calvert wrote a fantastic summary of lots of conversations on the MatExp Facebook page about this very topic. When I was thinking about this episode, the first thought I had is, are babies getting bigger over time?

That would be quite a reasonable assumption to make. There is an association between maternal obesity and fetal macrosomia. Macrosomia actually means an unusually [00:02:00] large body. There's plenty of evidence that women are becoming more obese when you look at the data in the uk, and yet if you look at the recent.

Office of National Statistics data on birth weight, the answer appears to be no. If you look at data comparing 2017 to 2009, which is the latest I can find, 10.5% of babies born in the UK have a birth weight of more than four kilos or eight pound, 13 in old money, near enough, nine pounds. So there hasn't been a change over that 12 year period.

So what is driving us to think that babies are getting bigger and to take more intervention as a result? Part of the driving factor, at least behind this is scanning. Are we scanning more? Yes, I would say we are. And that's with good [00:03:00] reason because there's a national drive to improve still birth rates.

The government and the Department of Health and the Royal College of Obstetricians and Gynecologists we're all working towards the aim of halving the number of stillbirths and neonatal deaths. And the most obvious place to start doing that is to try and pick up growth restriction in the womb earlier.

The largest category of avoidable still birth. Is fetal growth restriction. So obviously we're going to do more growth scans in the uk. This is done through risk stratification, so by no means all women are being offered a scan in late pregnancy, but we do see increasing numbers of women having third trimester scans as a result.

When I looked it up, there was a suggestion that 20 to 25% of women would fall into a higher risk [00:04:00] category and therefore need an additional scan during their pregnancy. This has to be counterbalanced with the fact that routine third trimester ultrasound has not been shown to improve perinatal outcomes in a recent, large study of 13,000 women in the Netherlands, so doing more and more scans.

Is not necessarily helpful and may increase intervention in that case. Is the collateral side effect of doing these scans to try and pick up growth restriction that we're picking up bigger babies, and then is it the language we use to inform women about the results that is damaging? There's been some discussion online and on social media about big baby versus healthy baby, and this is a tricky one because yes, I'd rather use the term healthy baby, [00:05:00] but strictly speaking, if the baby is growing rapidly, it may not be healthy.

Actually. We know that babies, particularly of moms with diabetes, What we call cherubic. They are like a cherub in a Renaissance painting, chubby, and we worry about that. That isn't a healthy baby. That is what we're talking about when we talk about macrosomia. We have a fascination with big babies. We mean to be helpful, but are we, I've had women tell me that their baby's been described as an elephant.

An obviously very unhelpful extreme example, but even this week in my antenatal clinic, I've had several women tell me they're scared of the size of the baby's head or the baby getting stuck, or the baby's shoulders being problematic, [00:06:00] and they're telling you this when actually the estimated weight may be only seven or eight pounds, a perfectly average size.

So are we confusing women? And making things more complicated than they need to be. We continue in this vein of making bigger babies abnormal when they're born. Sometimes we'll say, wow, what a big baby, almost a toddler. Women have reported to me when they've had a bigger baby midwives and other members of staff coming in to see the big baby that they've heard about on the unit.

And then in future pregnancies, when we see women, one of the important pieces of information is what size was their baby last time, and when they've had a big baby in the past, we might make unhelpful comments like, no wonder you needed an instrumental birth [00:07:00] or cesarean, or, well, if you can give birth to that size baby, you'll be absolutely fine.

this time. , or what a huge baby. Goodness me, your last baby was big. So we are inadvertently causing problems just with our conversations as an obstetrician. I think that scanning has definitely made things worse. Not only the fact that we are doing more scans, but also scan reports. Now detail centiles. So Centiles are, if you divide all babies into a hundred, then we will look at babies that are in the top 10%.

So the biggest 10% and the smallest 10%. And I discussed previously in my episode on scanning the fact that you take a series of measurements, make a calculation, and come up with an [00:08:00] estimated weight. So it can be that if the measurements are all on the higher side, that you come up with an estimated weight of a bigger baby.

But equally it can be that perhaps one measurement is particularly large. Skews the results making the estimated weight bigger. In the past, we used to get a report that perhaps just flagged the babies that were over the 95th centile, so top 5% or growth normal. Now we are getting much more detailed reports.

And again, this is partly because we want to pick up growth restriction. If you have a baby that was destined, for example, to be on the 60th centile, and then over time drops to the 20th centile, although that baby is a perfectly average size, its growth has slowed down. It could be becoming growth [00:09:00] restricted.

It's crossing the centile. So now on the report, we have a detailed account of what the Centiles are. This is very helpful in picking up growth restriction, but it's very unhelpful so that now even women with a baby on perhaps, the 85th Centile, the 80th centile, the 89th centile. That maybe previously would not have been referred to doctors or be concerned are now being told their baby's big.

Perhaps we need to work more closely with our sonographer colleagues to think more about the language you use to describe the results of a scan. So when we're faced with the answer of the scan, why is it that we sometimes resort to induction? One doesn't necessarily lead to the other. Induction is thought of because of [00:10:00] concerns about the baby getting bigger.

and making birth more difficult either for the baby or the woman. A difficult birth may mean an instrumental birth. It may mean more trauma or tearing for the woman, and in the case of shoulder dystocia, where the baby's shoulders get stuck behind the pubic bone, this can result in injury to the baby. Either fractures, broken bones of the collarbone or the humerus, the upper arm, or worse, a brachial plexus injury.

That is a nerve injury. By stretching the nerves in the baby's neck, you cause weakness in the baby's arm and hand. Fundamentally, this is what we're worried about. Let's take a look at what the guidance says. How can we avoid a difficult birth for a bigger baby? Starting with NICE. The National Institute of Clinical Excellence.

[00:11:00] This guidance concludes the induction of labor is not helpful, partly because there's no agreement about what constitutes a macrosomic baby NICE looked at greater than the 90th centile. greater than the 95th centile, or an estimated fetal weight of four kilos or four and a half kilos, so there's no agreements in the guidance as to at what point induction might be helpful.

The current guidance from the Royal College of Obstetricians and Gynecologists also talks about the fact that induction is not recommended, is not helpful. Mainly because it's looking at the same evidence. So one of the key facts I learned when I was training was that induction was not helpful in preventing a shoulder dystocia or [00:12:00] injury to the baby or woman unless the baby was more than five kilograms estimated weight.

To give you a feel, five kilograms is 11 pounds. That's considerably bigger than the 10%, four kilograms or nearly nine pounds that we've been talking about. Five kilograms is very rare. The nice guidance therefore, concludes that you would need to do 3,600 cesareans to avoid one brachial plexus injury. That's the nerve injury in the baby.

In women who are not diabetic. So if that's the case, why on earth would we consider intervention when a baby's growing a bit bigger than average? Let's leave the evidence for a moment. Think [00:13:00] about other factors. I believe one of the biggest factors is the Montgomery ruling. The Montgomery ruling happened in 2015.

And had profound implications for consent in all medical specialties, but particularly in this situation in obstetrics and gynecology. Montgomery was a mother taking her hospital to court because she had a bigger baby. And her obstetrician did not offer her as an option, a cesarean section. That is a very basic summary, and in the program notes, I've included a link to the Royal College of Obstetricians and Gynecologists response to it with links to some of the articles they wrote about how one might think about consent.

The Montgomery ruling was difficult for all [00:14:00] doctors. Not just obstetricians, and this was because previously there'd been something called the Boland principle, which meant that if a reasonable number of doctors would do the same as you, that was okay. The Montgomery ruling meant that one must clearly outline the recommended management strategies, discuss alternative treatments, discuss the consequences of not performing treatments.

Ensure women had high quality information, give them time to reflect on their decision check. Women have fully understood their options and implications and document everything in the women's notes. That sounds pretty straightforward, doesn't it? But is it any wonder that obstetricians are now fearful in Mrs.

Montgomery's case? [00:15:00] Upheld by the Supreme Court after 16 years of fighting, she had diabetes. So although the information about consent still applies, the situation was quite different. I believe the Montgomery ruling has made clinicians concerned. Are we becoming too over cautious? We're now so worried about the risk of shoulder dystocia and being sued that we do, we offer cesarean section or induction as alternative options.

I've mentioned diabetes there in the Montgomery ruling, so let's talk about diabetes for a minute. Diabetes does make a difference. Diabetes in the mother. That can be why a baby is more cherubic chubby, and we [00:16:00] see that in the abdominal measurement of the baby being bigger than average. So the guidance for offering induction or intervention is slightly different from a mother with diabetes.

There is some evidence that it may be helpful if the estimated weight is over four and a half kilogram. And one would need to do approximately 440 cesareans in diabetic women to prevent one case of brachial plexus injury. That's still an enormous number of cesareans, but it's tenfold less than in women without diabetes.

So we know that women who have high blood glucose levels tend to grow bigger babies. The difficulty is, We can diagnose not only preexisting diabetes, but diabetes of pregnancy, gestational diabetes, [00:17:00] normally, this is done by looking at a woman's blood sugar At 28 weeks, she will have a glucose tolerance test that is a fasting blood sugar and a blood sugar taken two hours after a sugar load.

Fair enough, not a problem. Then when we've diagnosed it, we may start her on treatment and get her to adjust her diet. All very important. However, there is some suggestion that if your baby is larger than average, think back to that 90th centile or if there's extra water around the baby that we should check for diabetes.

Because we know diabetes might be an underlying problem. So a woman who's had a perfectly normal G T T glucose tolerance test at 28 weeks, who then has a [00:18:00] scan because we're worried about the risk of growth restriction. Who then turns out to have a baby that's a bit bigger than average on the 90th Centile say, is then subjected to some home blood sugar monitoring and possibly a late diagnosis of gestational diabetes.

Alternatively, she may have her growth scan so late, maybe 38 weeks. That people conclude there's no point doing more glucose testing. Perhaps we should make an assumption that she does have gestational diabetes. And the logical secrete of that is perhaps we need to think about induction. We no longer have time to influence the size of the baby and the baby's health by changing her diet [00:19:00] or giving her treatment.

It's too late. The baby's nearly ready to be born. So instead we start talking about induction. There's good reason for induction in women with gestational diabetes. Perinatal morbidity and mortality. Late problems with a baby is much higher in women with preexisting diabetes. But where we can get in a muddle is when we fail to differentiate between preexisting diabetes and gestational diabetes, and also the control of the women's blood sugars.

If a woman's got good control of her blood sugars, then the national guidance with is even with gestational diabetes, that we shouldn't offer her induction until 40 weeks and six days. If however, she's got poor control or is needing medication, then the guidance is to offer induction [00:20:00] 38 weeks. So the confusion of diabetes and gestational diabetes.

Is also where the induction conversation comes in. So having talked a lot more about science and guidelines than I generally do in my podcast. Now imagine you are an obstetrician sitting in the clinic. You might have 15 women to see during the course of the morning. Some of these will be women that have been sent in to see you because they've had a scan, what we call a scan review.

The woman will come in, she's perhaps in the third trimester. She's had a scan originally because she was screened at risk of growth restriction, and instead the babies on the 90th centile, let's say she's 36 weeks, quite a common time to have [00:21:00] a growth scan. She's come out of the scan. And you might ask her, what did the sonographer say about the scan?

And she might say to you, the sonographer said, there's no problem with the growth of the baby. In fact, if anything is growing really well, it's bigger than average. Now, I'm a bit scared about giving birth. So imagine you obstetrician, what are you going to say? And. so you can try and reassure her that it's very likely that this is a normal healthy baby.

You can explain that there is a margin of error with scans and that actually the margin of error could be 10 to 20%. And sometimes I've had that conversation with women and I've said it's completely possible that actually your baby isn't as big as you think. And [00:22:00] it's smaller. There's quite a margin of error with scans at this stage of pregnancy.

But then I've had women counterbalance that with, well, yes, it could be smaller, but what if it's bigger? There's a margin of error in both directions, isn't there? Well, obviously yes, that's true. Then comes a conversation about what you do about it. Options are, do nothing. This is a nice, healthy baby.

Everything's going well with her. Pregnancy, suggest you leave things well alone and let nature take its course. If she's fearful about birth though, you are likely to get into a conversation about induction of labor. You may get into the pros and cons of induction. What does induction involve? What are the success rates?

What are the risks, and [00:23:00] what's the optimal time? Do you offer induction at 38 to 39 weeks or do you offer induction at 40 weeks if she hasn't gone into labor when her body's likely to be more? That conversation might spiral away into, well, I know induction's not very nice. I've heard lots of people have bad experiences of it.

If my baby's bigger, I'm more likely to need an instrumental birth, which I've also heard bad things about and my friend recovered badly from. Shouldn't I just be thinking about a cesarean section? rapidly, the conversation has gone from a scan review of a scan that was being done in the first place to rule out growth restriction and prevent stillbirth into a series of interventions and down a rabbit hole towards induction of labor or cesarean section.

[00:24:00] So now this woman's options are, wait, do nothing. Repeat the scan in a couple of weeks and see what the size of the baby's like. Then that uses up more resources, more ultrasound that isn't needed, might make matters worse, but might be more useful than that Single data point induction of labor at a varying number of weeks or.

Elective Cesarean because we are now so scared of intervention during our labor that that seems the best option and all this is happening. Whilst the obstetrician who wanted to just say everything was normal, go back to midwifery led care has numerous women waiting outside the door with other things that they need to look at and discuss.

And therefore has considerable pressure of time on them in [00:25:00] which to make the decision. If we turn back to Montgomery, let's just remind ourselves what we're supposed to be doing. We are supposed to be giving women, we are supposed to be giving women the recommended management strategies and procedures.

So for this, that would probably be. Do nothing, discuss alternative treatments that would be induction or cesarean. Discuss the consequences of doing nothing. Well, that could be a completely straightforward, normal birth all the way through to a terrible shoulder dystocia or difficult caesarean. Ensure women have access to high quality information to aid their decision making.

Well, I'm going to include some of those links in my podcast program [00:26:00] notes give patients adequate time to reflect before making a decision. I think this is a key one. Often we think that women should make a decision in the clinic in front of us and actually, We should give women more time to go away and reflect and think and ask more questions before making a decision check.

Women have fully understood their options and the implications. Do we do this? I'm not sure we do. We talk at women. We do give them chance to ask questions, but remember I said there's that time pressure and then we've got to write it all down in the women's record in 15 minutes. So it's no wonder that we end up with intervention.

We end up with an obstetrician feeling completely overwhelmed by the huge number of risks and things they need to discuss with the woman. We have a woman who's [00:27:00] now scared and bamboozled by not only information she wasn't expecting because she was going for the scan, expecting to rule out whether her baby was small.

Suddenly nose diving into a whole heap of intervention that she hadn't anticipated and hadn't had time to think about. So personally, I think that's how we end up with lots of inductions for large for dates. But why recently? So recently, now you've got to catapult in a whole different question. The Cochrane Review.

The Cochrane Review is a highly respected resource. It looks at trials done covering a specific topic, and does some meta analysis. That is, it details everything together and draws some conclusions. So this will be helpful, won't it? Well, [00:28:00] the problem is that a Cochrane review of pregnancy and childbirth.

Did a review of induction of labor for big babies. Babies over four kilograms or nine pounds. They looked at women without diabetes and what they suggested was that induction may reduce the amount of fractures, induction may reduce the amount of shoulder dys. Decreasing shoulder dystocia by 27 babies per thousand with Brachi plexus injury.

The nerve injury I mentioned there wasn't a clear difference. Did it decrease the baby's birth weight? Yes. Induction baby's weight approximately 178 grams less when labor was induced. Then they looked at what's best for women. [00:29:00] Induction of labor didn't make a clear difference to cesarean section, and it didn't make a clear difference to instrumental birth.

Slightly bizarrely induction seemed to increase the number of women with severe tears. So what does this mean? They concluded there appear to be benefits from induction. But there may also be disadvantages and the option should be discussed with parents when their baby is suspected to be big. They suggested we need more trials, so it's no wonder that doctors are a bit confused and women also the evidence is compelling.

Most of the time one thinks about induction of labor. Increasing intervention, increasing cesarean, increasing instrumental birth, but it didn't. Most women will choose the health of their baby [00:30:00] over the health of themselves. So the fact that induction reduced fractures and reduced shoulder, women would usually choose that over the fact that they had more tears.

But this evidence. It directly contradicts the NICE guidance and makes life difficult. What set of guidance should we follow? The evidence is confusing. We need more information. So now there's something called the Big Baby trial being undertaken at Warwick University. Yes. It's an important question, but are we creating problems that don't exist?

Are we moving towards a situation in which women don't have confidence in their body's ability to carry a baby and go into labour? Naturally, induction rates are rising [00:31:00] up and down the country. Yes, it's true. By cutting the pregnancy short, we can make the baby a bit smaller, but 178 grams, that's not that much.

And what on earth do women make of all this, I'd like to now share a poem, a Woman's Perspective, written by Jenny, my great friend Gill Phillips', daughter, about her own pregnancy, the too big not growing baby. The test was positive. We were so delight. Our baby was the size of a poppy seed, but the following week I had a bleed, and in one moment, all my feelings of elation turned to devastation.

I prepared myself for the worst. The sonographer was able to see the pregnancy ntic topic in the right place. What she could see was as good as could be at such an early stage. [00:32:00] Another scan booked for 10 days later. It felt like years there were lots of tears awaiting our baby's fate. At seven weeks, a tiny flicker on the screen, the heartbeat of our little bean.

What a relief. We were in disbelief by 12 weeks doing somersaults and headstands with tiny feet and tiny hands. It felt so surreal as I couldn't yet feel the wrigley baby inside me. At 20 weeks, we were relieved to be told everything was fine. Brain, kidneys, bladder, spine, but the baby wasn't playing ball.

Couldn't check the heart at all. Come back next week for a repeat. In a week, the heart was fine. We thought we were done. In reality, we'd hardly begin. I went on to have another four scans. My bump was measuring big and then there was not enough growth. How could it be both? Time off [00:33:00] work, parking, waiting each time.

The challenges were frustrating. Worth the effort. Of course, I know, but in the end, my baby's weight was normal. It just goes to show. Now, what about zesty bit? I think the whole team needs to be cautious about language used. The inadvertent side effect of doing more growth scans and trying to reduce the stillbirth rate, the damage we are possibly doing by introducing intervention off the cuff remarks can be unhelpful, misleading.

Faced with a concerned woman, what's an obstetrician supposed to do? The Montgomery ruling has definitely not helped this particular clinical situation, but I would argue that in the Montgomery ruling there is also the answer. [00:34:00] We need longer appointments with women. We need better antenatal education.

Better information for women, and when you are asking a woman to make a decision about an intervention, I think the key thing for me from the Montgomery ruling is we need to give her time. We need to give her time to reflect on what we've told her. We need to give her written information to back up what we've told her, and we need to leave her time to go away and think about what we've said and decide what she wants to do.

I think far too often in maternity, we expect people to make decisions on the spot in front of us, and it's not really necessary. If you're a woman, make sure you've asked all the questions. Make sure you have the information you need to make your choice, and don't be rushed into something. [00:35:00] Ask for time.

Ask to be able to consider your options and how you will contact the hospital and let them know your decision. But also don't be scared if someone tells you your baby's big. Someone told me this week in. That one of the few advantages of being pregnant in the time of covid is that everybody isn't reaching out to touch your belly anymore.

Your pregnancy bump belongs to you once again, but it doesn't stop people making unhelpful comments, do you any minute? Are you what? Not till Christmas. You are big. All of us have a part to play in this conversation and the ripples that flow out. I'm hoping that this episode has answered some of the questions and some of the thoughts that I've seen on social media.

I've put quite a lot of links in today's program notes in case you want to read and understand [00:36:00] more and explore this particular topic in more detail. So I do hope you've enjoyed listening to the obs pod. If you have, do like, subscribe or leave a review and join me again to explore more about the life of an NHS obstetrician.

I'm finding it really exciting to have people listening and give me feedback about what they've found interesting. So please do recommend the ObsPod to other friends. Colleagues or people who you think might find it interesting. I'd love it if you'd share with me what you've enjoyed about listening and if you've done anything differently as a result, I can be found on Twitter.

@fwmaternity and @TheObsPod, and please do check the MatExp hashtag #MatExpand the [00:37:00] website matexp.org.uk for more information and ideas on how to improve women's experience of maternity. Finally, I'd like to reassure you that I take confidentiality very seriously and although I'm talking about experiences from my working life, I'm taking great pains to make sure that I anonymize the stories and talk in more general terms so that I keep confidentiality of my women I currently care for and have cared for in the past.

Very safe. Many thanks for listening.