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When does NICE recommend offering induction for women with uncomplicated pregnancy?

January 23, 2020

41+0, 41+3, or 42+0?

The recent SWEPIS trial from Sweden (click here) in which no baby died after induction at 41+0 compared to six deaths among those allocated to induction at 42+0 provoked some soul searching in Scandinavia.

And last week a group of Danish obstetricians invited me to consider whether they should change the gestation at which they offered induction for women with uncomplicated pregnancy from 41+3 (click here for guideline in Danish) to 41+0, i.e. three days earlier.*

I said, “Yes. Women don’t have to accept the offer, but most will, and the earlier date will prevent baby deaths, without increasing Caesareans. Women’s labour experience will be no worse, and no more painful. It may even be better and less painful.” I cited the ARRIVE (click here) and 35-39 (click here) trials in support of the latter assertions.

As an aside I said that the UK National Institute for Clinical Excellence (NICE) recommends offering induction between 41+0 and 42+0 weeks, but that the guideline was under review and I anticipated that the new version would recommend 41+0. To my surprise the audience told me that NICE already recommended 41+0.

They were right (click here for the summary and here for the full CG70 guideline. It’s on p24).  It reads: “Women with uncomplicated pregnancies should usually be offered induction of labour between 41+0 and 42+0 weeks to avoid the risks of prolonged pregnancy.”

I had read that as offer the induction between 41+0 and 42+0 weeks. i.e. an offer to induce as late as 42+0 was acceptable. But it goes on to say;

“The exact timing should take into account the woman’s preferences and local circumstances.”

This removes any ambiguity. I had misread it. The offer must both be made by 41+0, and include availability of induction from 41+0, so that the woman can choose the timing.

Consider a woman whose fetus died at 41+1, with an appointment at 41+2 to discuss induction. I used to believe that her carers had followed NICE’s guidelines. But the correct reading is that they had not done so.

So why does NICE not say, “Offer induction at 41+0 weeks, and let the exact timing take into account the woman’s preferences and local circumstances”? Perhaps they should.

Does it matter? If 2/3 of pregnancies are uncomplicated, 20% reach 41+0 weeks, and if the number needed to induce to prevent a stillbirth at 41+0 weeks is 500, induction then rather than at 42+0 would save 160 baby lives each year in UK. In practice the gains will be smaller because a lot of inductions are already offered at 41+0, but there would be some easy wins.

Jim Thornton

* The average pregnancy lasts 40 weeks+0 days. So 41+0 is a week over the average, albeit well within the “normal” range. 42+0 is two weeks over the average. The current Danish standard 41+3 is  Term plus ten days.

Standard, Population & Customised fetal growth charts addendum 18 – the DESiGN trial

December 22, 2019

Jim’s prediction of the DESiGN trial results & why he won’t believe ’em

DESiGN (DEtection of Small for Gestational age Neonate) is a cluster randomised trial comparing the Perinatal Institute’s GAP/GROW protocols (click here) with standard care for detection of small for gestational age babies.

There are good things about it. It was registered here ISRCTN 67698474 on 2 November 2016, the protocol was published in March 2019 (click here) and the triallists include some very big names, Matias C. Vieira, Sophie Relph, Andrew Copas, Andrew Healey, Kirstie Coxon, Alessandro Alagna, Annette Briley, Mark Johnson, Deborah A. Lawlor, Christoph Lees, Neil Marlow, Lesley McCowan, Louise Page, Donald Peebles, Andrew Shennan, Baskaran Thilaganathan, Asma Khalil, Jane Sandall, and Dharmintra Pasupathy.

But DESiGN won’t tell us anything about the benefits or harms of customisation itself.

DESiGN is comparing units using GROW customised software with units using an unspecified local population chart. The intervention group are also receiving training in measurement techniques and in how to respond to abnormal values. Many control units are apparently not even using a chart for fundal height measurement. Instead fundal heights are “approximated to the gestational period” in that the number of centimetres is expected to approximate to the gestational age in weeks (± 2–3 cm). This rule aligns with no fundal height chart ever.

At best DESiGN will tell us that it’s better to train people to measure fundal height properly, plot it on a chart and act on the results, than to not train them, let them ignore fetal size altogether, measure it by palpation alone or tape measure, plot the values they get on any old chart, or approximate them to an erroneous (± 2–3 cm) simplification, and act on the result according to whim. The former will likely be better, but it will hardly prove the benefit of customisation.

Perhaps my subheading above is unfair. Perhaps DESiGN is simply a pragmatic evaluation of GAP/GROW against current real world practice, with no implications for the customised chart debate. If so, the triallists will hear no more from me.

But the protocol suggests that at least some of the authors hope to draw implications about the value of customisation. In that case, I look forward to reminding them that it won’t.

I’ve not seen any results, so my date-stamped prediction (click here or Jim’s DESiGN prediction) is data independent.  We shouldn’t have to wait long.  According to the protocol the last sites were randomised in July 2017 with outcome data to be collected till 31 November 2018. According to the registry the intention to publish date is now 28 February 2020.

For more on click here.  For the customised v standard chart debate click here.

Jim Thornton



The story behind an ill-judged tweet

December 15, 2019

Menopausal Hormone Therapy & Quality of Life

Advice from the UK Medicines and Healthcare Devices Regulatory Authority (MHRA) and US Federal Drugs Agency (FDA) hasn’t changed in nearly 20 years. The risks of breast cancer and stroke are small, but not zero, and outweigh the benefits in reduced fracture risk.  Menopausal hormone therapy (MHT)1 should be prescribed for symptoms alone, i.e. not for health promotion, and in the lowest dose and for the shortest time possible.

When someone I follow, Dr Mark Porter2, tweeted the MHRA’s recent table of risks Table1, I commented.

“The elephant in the room is that women are supposed to weigh up these risks against the quality of life gain. But menopausal hormone therapy has minimal benefit on QoL either.” Link to WHI QoL trial in New Engl J Med. More on that later.

Dr Porter; “That’s not the impression I get in the consulting room.”

Me: “Me too. Presumably what we’re seeing is either a placebo effect, or a short term benefit to which tolerance develops.”

And then a thought popped into my head. An analogy with another drug that gives short term symptom relief but definitely does not improve quality of life. Heroin.

Me: “Estrogen is addictive & withdrawal is bad. Loose analogy, but if you doled out heroin you’d get patient feedback that it was great stuff. But RCT of H v placebo would likely not show much benefit on qoL!”.

“Loose analogy” doesn’t absolve me. It was ill-judged. I’m sorry. Here are the screenshots.


It soon went viral as an example of the worst sort of male chauvinism, an ignorant, “mansplaining” gynaecologist. Someone threatened to report me to the president of the RCOG. Someone did complain to my boss, the Dean of Nottingham Medical School. Twitter’s leading gynaecologist, @DrJenGunter weighed in.  I follow and admire Dr Gunter2, but attempts to defend yourself on Twitter often backfire. So I did what I’d done after a similar episode in relation to home birth (click here), muted the thread and went off to dig my allotment.

But a week has passed, so let me try to explain.

Weighing the symptomatic benefit of menopausal hormone therapy is not straightforward. The symptoms relievable by estrogen fall into two main groups, vasomotor hot flushes, and the effects of local deficiency on the vagina and bladder. The latter are best treated by local estrogen cream or pessaries, with as far as we know, little or no systemic risk. Only the hot flushes require tablets, implants or patches, the forms of estrogen, which cause the harms summarised in the table above.

Hot flushes are a response to falling estrogens rather than a feature of stable low levels. They often recur when estrogen is stopped, which is one reason why some women end up taking long term estrogen. My tweet about quality of life should have made clear I was referring to the long term.

Many quality of life studies are short term, sponsored by pharma, or pretty poor quality. But there is one primary source of high quality unbiased data. The Women’s Health Initiative (WHI) studies. These two enormous trials funded by the US government showed in the early 2000s, that far from being protective of cardiovascular disease and stroke, menopausal hormone therapy increased both. Prior to WHI the observational data on cardiovascular disease had largely been favourable. Some small trials had shown harm but the sponsoring manufacturers had concealed adverse cardiovascular and stroke events (click here and here) and played down the breast cancer risks. When the WHI trials were published the MHRA and FDA changed their advice to “not for health promotion, and in the lowest dose and for the shortest time possible”. Prescriptions fell dramatically and soon, so did breast cancer (kumle2008).

The drug companies were not pleased and ever since have paid doctors to criticise the WHI trials or downplay the risks. But biology doesn’t change. The trials have not been superseded, and remain the highest quality ones in the various Cochrane reviews (e.g. click here). The WHI QoL study I cited (click here) concluded.

“Estrogen plus progestin did not have a clinically meaningful effect on health-related quality of life.”

“Among the subgroup of younger women age 50 to 54 years of age with moderate-to-severe vasomotor symptoms it did improve vasomotor symptoms and resulted in a small benefit in terms of sleep disturbance but no benefit in terms of the other quality-of-life outcomes.”

It was a placebo-controlled trial, but my tweet suggesting that women who take estrogen to relieve hot flushes are experiencing a placebo effect provoked an understandable backlash. The short term effect on hot flushes is not a placebo effect. That was wrong.

But all drugs have some placebo effect. It’s not denigrating the experience of women going through the menopause to say so. It’s simply a fact. Women who are considering taking a drug to control menopausal symptoms, need to know if the placebo-controlled trials show it overall improves quality of life. For women with moderate-to-severe vasomotor symptoms short term, it does. Overall and longer term it does not.

One possible reason is that people given estrogen experience pleasant effects but gradually become tolerant. When estrogen was given by implants some women came back for repeat implants at ever decreasing intervals, with estrogen levels far above even the pre-menopausal range. This also occurs with patches, but not with oral tablets. When treatment was stopped in the WHI trials more than half the women in the active treatment group experienced withdrawal symptoms (click here).  See also bewley1992.

Summary one

The risks of MHT are not very great, and it is reasonable for women to take it for symptoms. However, local symptoms are better treated with safer local therapy. Only hot flushes need tablets or patches. But women should surely be told that these may simply defer the symptoms till the course is finished, withdrawal may not be easy, and long term treatment does not overall improve quality of life compared with placebo. The explanation for this is not completely clear but may be related to the fact that people become tolerant to the beneficial effects of estrogen.

But why keep mansplaining?

Because big pharma pays medical societies, and opinion leaders, to mislead women. Some doctors write dozens of partisan papers (click here). Other doctors get taken on conference trips to the Caribbean to be told how the WHI trials were flawed. For just one example (click here). Conflicted doctors advise on, and appear in, films about women missing out on life saving menopausal hormone therapy (click here).

It’s still going on. Conflicted doctors influenced the current NICE guidelines (click here), while real experts were ignored (click here). The largest, best quality, and most up to date review of the risks of breast cancer in the Lancet earlier this year (click here) suggested that the risks were about twice as high as NICE had estimated. Within days the British Menopause Society (BMS) was downplaying the risks (click here). The Guardian covered the story rather well (click here) but didn’t report how many conflicted doctors remain BMS trustees or on their advisory council. You have to dig deep (click here) to learn that the BMS still takes money from hormone manufacturers.

At one point in the Twitter thread someone advised me to read an article by Professor Susan Davis of Monash university. No, no, no! Professor Davis is one of ten high profile doctors called out by Andrea Fugh-Berman and her colleagues from Georgetown university (click here) for taking money from pharma to write biased opinion pieces in favour of menopausal hormone therapy.

Someone else pointed out that the debate about my tweet had reached the magazine and discussion board Menopause Matters, edited by Dr Heather Currie. Read about her conflicts and links with manufacturers here.

Women need to know who’s pushing this stuff.

My story

Much of the Twitter criticism came from women saying that their personal experience trumped any evidence I could come up with. I get that. Stories are important. But they cut both ways. At the risk of weakening the rest of this post, here’s mine.

About 35 years ago my mother asked me – then a young OBGYN – whether she should take hormone replacement therapy, as it was then known, to prevent fractures. My answer:

“Yes. It’s good for your bones. There may be a small breast cancer risk, but that’s far outweighed by the benefits to your arteries in terms of reduced heart attacks and strokes”.

Orthodox advice then. My mother, who still had her uterus, took combined HRT, and suffered a fatal stroke in 2001. She died three months before the WHI trial of combined HRT was suspended by its data monitoring committee because, far from preventing strokes, it caused them. Wyeth’s share price fell off a cliff. The MHRA and FDA changed their advice to “… never for health promotion”. And I learned why randomised trials matter.

I’m not seeking sympathy. My mother was a good age. You’ve got to die of something, and I’m told there is only about a one in four chance that her stroke was caused by the HRT that I had recommended.  But…, stories are important.

Summary two

There are two narratives around menopausal hormone therapy.

One is simple and easy to understand. It is a highly effective, safe and underused treatment that some misogynistic male doctors, who never have and never will experience a hot flush, are reluctant to prescribe.

The other is a bit more complicated. Drug companies and some doctors are making money from medicalising a natural, variably unpleasant, but self-limiting transition. For years they misled women by hiding and downplaying the risks. When neutral researchers finally did good trials, they paid doctors to undermine the results.  And they’re still pushing conflicted doctors onto the NICE committee. Hiding the evidence that although estrogen relieves hot flushes while you’re on it, you might find it difficult to stop. And long term it won’t make you feel better and has rare but serious side effects.

I’m sorry for my ill-judged tweet. Perhaps it’s fortunate that women don’t need to listen to me.

Better to listen to the genuine independent advice that comes out of the MHRA and FDA, and the independently assessed evidence collected by Cochrane.

Jim Thornton


  1. This term is preferred to Hormone Replacement Therapy (HRT) for hormones given after a natural menopause. The latter should be reserved for women who have undergone a premature menopause due to surgery or disease.
  2. I’ve named names in this and other blogs. But, so far as I’m aware, neither Dr Porter nor Dr Gunter have ever received money from the manufacturers of menopausal hormone therapy and their writings on this topic seem completely fair and unbiased. They are not in my sights.

Jim’s growth chart navigator

November 23, 2019

September’s series on fetal growth charts took 16 posts to show why customisation is usually a bad idea. Some readers found them hard to navigate. This may help.

1. A tongue-in-cheek scene-setting about why it would be silly to use special United States baby weight charts.  And how some US paediatricians do exactly that (click here).

2. Technical stuff about scanning & how to create unbiased growth charts (click here).

3. The difference between population (reference) charts, and standard (healthy) ones (click here).

4. Customisation is not always bad. The principles of when it is a good idea, & when not (click here).

5. The theory (click here), & 6. the practicality (click here) of customising by race or ethnicity.

7. Customising on maternal weight (click here), 8. height (click here) or 9. parity & fetal gender (click here).

10. A digression on estimated fetal weight (click here).

11. Intergrowth-21 standard charts (click here) & 12. WHO standard charts (click here).

13. The Intergrowth/WHO plagiarism controversy (click here).

14. GROW customised charts (click here). Why almost everything about them is wrong. The reason I got embroiled in this topic.

15. Empirical studies (click here).

16. Summary (click here).

17. Addendum for twins (click here).

Jim Thornton

Home birth again

November 20, 2019

Most people imagine hospital is the safest place to be born, and it is if your mother has obstructed labour, major bleeding, or eclampsia. But hospital also has dangers. Not just infection, and blood clots, but staff led astray by false positive tests, or intervening “to be on the safe side”. Hospitals can also harm.

Consider the low-risk woman, without problems so far, who’s lucky enough to live in a rich country with skilled midwives who can look after her and her baby at home, but transfer if necessary.  Could planning to birth at home be equally safe?  Randomised trials are impossible, and simply comparing women who birth in either place is hopelessly biased because the groups are so different. The best we can do is compare cohorts of women judged low-risk at the start of labour, by “planned” rather than “actual” place of birth.

Two recent studies have done just that. The first from Canada (click here) retrospectively identified women without a risk factor before the onset of labour, classified them into planned home, or planned hospital, and randomly matched 11,493 in each group by parity and by whether or not they had had a previous Caesarean; apparently the latter is not judged a contraindication to home birth in Canada. There is potential for bias in this sort of retrospective matching, but the authors did their best to avoid it. The risk of stillbirth, neonatal death or serious morbidity did not differ significantly by planned place of birth (relative risk [RR] 1.03, 95% confidence interval [CI] 0.68–1.55). These findings held true for both nulliparous (RR 1.04, 95% CI 0.62–1.73) and multiparous women (RR 1.0, 95% CI 0.49–2.1). There were also fewer interventions among planned home births.

Last week (click here) a similar analysis came from Australia. Again the authors did their retrospective best, identifying 8,212 planned home births among low-risk women, and comparing them with a much larger number of planned low-risk hospital births. There were only nine baby deaths in the planned home group, but this was a slightly higher rate than for the planned hospital group, RR 1.6 (0.65–3.7). When divided by parity the differences were more marked in primiparous women RR 2.1 (0.58–7.8) than multiparous women 1.3 (0.4–4.1). But as the confidence intervals show, all the differences could have occurred by chance.

If these were the only studies, few partisans from either side of the home birth debate would be convinced. They are too small for precise estimates and there’s too much scope for retrospective classification errors. But they’re not.

The 2011 UK Birthplace study (click here) included 17,000 low-risk women planning birth at home, and was much more rigorous. Classification of risk and planned place of birth was done prospectively, before labour started. This reduces bias. In Birthplace for low-risk women having a first baby, planned hospital birth was safer for the baby, 5.3 v 9.3/1000 adverse perinatal outcomes, despite nearly half transferring to hospital in labour.  For second or subsequent births, there was no difference in adverse baby outcomes, the transfer rate was only 10%, and home birth substantially reduced intervention.

A similar 2015 study from the Netherlands (click here) included 466,112 low-risk women who planned to have a home birth at the onset of labour and 276,958 who planned a hospital birth. For first births the RR of baby death was 0.94 (0.76–1.16) and for second and subsequent births 1.02 (0.78–1.33).

Taken together the data are reassuring for low-risk multiparous woman in a rich country like UK, Netherlands, Canada or Australia where midwives are registered and well trained. For anyone like me who’s worked in hospitals for 40 years and seen both wise and unwise interventions, these data are plausible. Planned home birth, with transfer to hospital if problems develop, is safe, and intervention rates are much lower. For first births the highest quality study from the UK, Birthplace, suggests hospital is a bit safer and transfer rates are rather high.

The NHS is right to offer all low-risk multiparous women a home birth.

Jim Thornton

Note. Before anyone asks, birth in a midwife-led unit, whether freestanding or alongside a consultant-led unit, is safe for low-risk mothers, whether having their first or subsequent births. But everyone knows that. It’s hardly controversial any more.

Refusing Down’s screening

November 11, 2019

A woman successfully sued the NHS last month for not diagnosing and aborting her Down’s fetus after she had apparently declined screening (Mordel v Royal Berkshire NHS Trust, click here or 2591).


Women considering Down’s screening need to know what they are getting into. Screening only gives a risk. If it’s high a needle test will confirm the diagnosis, but may cause miscarriage of a normal fetus. And the “treatment” is abortion. If you don’t want that, steer clear.

Midwives and sonographers must ensure that everyone who wants screening gets it, but avoid normalising it, or offering it in such a way that women get pressured into acceptance. It’s easy for compliant, or confused women to get sucked passively in.

The facts

My summary. Numbers refer to the judgment paragraphs.

Mrs Mordel was offered Down’s screening by her midwife, Ms Foley, and “accepted” combined screening at 11-13 weeks. This meant adding a measurement of the thickness of the skin over the back of the neck (nuchal test) to the routine scan, and undergoing an additional blood test. She expressed doubt as to whether, if the screening showed a high risk, she would undergo the second phase needle test with its small risk of causing miscarriage [8].  The midwife booked the scan and nuchal test, and gave her the NHS Down’s screening leaflet, which Mrs Mordel decided not to read because she had watched a You Tube video and “understood the position” [36]. In cross-examination, she confirmed that she had a good command of English and was quite comfortable in dealing with medical professionals in English [31]. When she attended later for the scan the following exchange took place.

The sonographer, Ms Bracher, having introduced herself, asked “Do you want the screening for Down’s syndrome?” Mrs Mordel said “No”. Ms Bracher said, “So we are not doing the screening then, we are just doing the dating scan and I will be checking the baby and making sure that the dates are correct”. There was no response from the claimant. The claimant was asked to lie down on the table. Ms Bracher then clicked on the box in the dropdown menu, “Down’s screening declined”, and this was not a mistake – the claimant had said “no” and nothing else.”[55]

At the end of the scan the sonographer wrote “Down’s screening declined” on the report, a copy of which she filed in Ms Mordel’s hand held notes, and which Ms Mordel agreed that she had read [38]. The screening blood test which Ms Mordel should have been expecting was not done, and no screening result was ever issued. At later visits with her midwife no further discussion of Down’s screening took place. A Down’s affected baby was born.

The claim and the ruling

Mrs Mordel initially claimed that the sonographer had not said anything, but the judge rejected that, leaving her alternative claim that the counselling described above was inadequate. Five experts were divided and the judge couldn’t choose between them [134]. He considered the following factors.

There were language issues. Mrs Mordel was Polish[8] . Her “English is good but far from excellent” [21], although she was “happy to receive the NHS booklet in English rather than Polish” [23].

She was not the sharpest tool in the box, although he put it in judicial language. “There were occasional failures to understand what was being put to her by both counsel, particularly if the question or proposition had a degree of nuance or complexity. On reflection, and with respect to the claimant, I put that down not primarily to lack of competence in the English language (although it remains a significant factor) but to her general level of education and sophistication” [21].

She really wanted the test. This was an unplanned pregnancy [8], her mood was low [8]. She had no religious and ethical objection to abortion. Although a Roman Catholic, not that she described herself in that way, my sense of her evidence was that she was not particularly devout and in cross-examination she said that she attended Mass 3-4 times a year when she felt a need to. She has previously used contraception and has not married her partner [30].

And he believed her. He found her a guileless witness and therefore believed her statement soon after the birth, that she thought that having asked for testing, she had been tested. Much of his argument took the form that since she clearly had misunderstood, she must not have been adequately informed.

He ruled that Ms Bracher the sonographer should have questioned her harder [98, 99], and that “Midwife Foley failed to discharge her duty […] in not exploring why the combined test had not been carried out” [141]. At that later time point there would have been time for an alternative screening test.


Coo-er! It all sounds rather patronising – the staff should have triple-checked because she was a stupid foreign unmarried woman with an unplanned pregnancy who didn’t understand plain English! But I wasn’t in court. Nor probably were you dear reader. We can only comment on what we read.

But the judge revealed, in my opinion, a serious misapprehension, namely that non-directive counselling is easy. “The steps required to guard against parental choice not being respected are not onerous” [86].

Really? Yes, the sonographer could have pressed more. Yes the midwife could have asked why she’d changed her mind. But this is what we teach sonographers and midwives not to do.  Don’t question women’s decisions.  That is the way people get bullied into screening that they don’t really want.

To be fair the judge anticipated and rejected this criticism [90]. In his opinion that risk only arises in the event of maladroit or insensitive interrogation, and NHS professionals are well habituated to avoid that. He was careful not to argue that only women who decline screening should have their refusal double checked. Having established [51] that Ms Bracher would have spoken in the same way, to a woman who had changed her mind to undergo screening, he argued [95] that this would also have been inadequate because of the risk that patients who did not want screening for Down’s syndrome would end up having the nuchal test.

Midwives and sonographers have difficult jobs. Let’s hope they all do better. That they double check both those women who change their mind to decline, and those who shift to acceptance, and do it in such a sensitive way that no-one feels bullied into testing.

Let’s hope they don’t only double check vulnerable non-English speaking decliners, and that more widespread questioning doesn’t pressure more women into testing they don’t really want.

Jim Thornton



Standard, Population & Customised fetal size charts 17 – addendum for twins

September 29, 2019

Twins, especially identical ones,  tend to be smaller than singletons (click here). This has led to the suggestion that they should have special charts (click here, and here). The support group, the Twin and Multiple Birth Association, (TAMBA) apparently supports the idea (click here), but it’s a bad one.

The Perinatal Institute, normally an advocate of customisation,  explains why rather well (click here). To quote:

The [twin] charts […] are based on reference values derived from the whole population, not only from uncomplicated pregnancies. Therefore, they do not represent a normal growth standard but one that may have been affected by an unspecified number of pathological factors. This concept is particularly important in twin pregnancies as they have a substantially increased number of complications.”

“The pattern of slowed growth from 30-32 weeks in many (but not all) twin pregnancies may be pathological due to late onset fetal growth restriction associated with placental insufficiency,
which usually also becomes manifest from around 32 weeks. Adjusting the curves downwards may normalise pathology, reduce recognition of pregnancies at risk, and lead to false reassurance.”

Correct. Twin smallness is not healthy smallness. Twins also have higher rates of stillbirth, cerebral palsy and other problems. The reasons not to customise by ethnic group (click here), height (click here), weight (click here) and parity (click here), also apply to twin customisation. Special “small” charts for twins condemn them to being classified as “normal for twins”.

The Italian group (Ghi et al click here) recognise the problem; “adjusting for multiple pregnancy, thereby shifting the normal range of fetal growth downward, has the potential to mask truly growth restricted twins and increase perinatal morbidity from failure to recognize growth restriction”, but hope that because they excluded twins born before 36 weeks, or below the 5th centile on a singleton chart, that it will go away. They compare their twin chart with a local customised Italian one (click here) but provide no data of the detection rate of pathology.

The STORK study authors (here) compared detection rates for stillbirth, with a singleton chart. But their chosen comparison chart (Poon click here) which correctly excluded babies of smoking mothers, and those with major medical disease, has it’s own problems. Leona Poon not only based her chart on routinely collected data with all the error and bias that entails, but also used the weights of babies who were actually born, which seriously distorts the preterm part of the chart (click here).

Many twin fetuses fall below the Intergrowth-21 or WHO singleton growth standards. Some even below the 1st centile. These are reasons both to use charts with reasonably precise extreme centiles, and to consider delivery before term (click here).  Some experts also recommend basing decisions on estimated fetal weight discordance (EFW) a sign of selective growth restriction, is included as a factor in delivery timing. If so, it is preferable to use the most accurate and unbiased  Intergrowth-21 EFW formula (click here).

TAMBA should think again.

Jim Thornton

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