Where do all those numbers in the newspapers come from? The Commons Committee on Science and Technology is taking evidence on ‘scientific developments relating to the Abortion Act 1967’.
Scientific and medical expert bodies giving evidence say that survival in births below the twenty-fourth week of pregnancy has not significantly improved since the 1990s, when it was only 10–20 per cent. But one expert, a Professor of Neonatal Medicine, says survival at twenty-two and twenty-three weeks has improved. In fact, he says survival rates in this group can be phenomenally high: 42 per cent of children born at twenty-three weeks at some top specialist centres. He has been quoted widely: in the Independent and the Telegraph, on Channel 4 and Newsnight, by Tory MPs, and so on. The figure has a life of its own.
In the media, you get one expert saying one thing, and another saying something else. Who do you believe? The devil is in the detail. One option is to examine the messenger. John Wyatt is a member of the Christian Medical Fellowship. He didn’t declare that when he went to give evidence. You don’t have to. He did declare it when asked.
Prof Wyatt has relevant research experience, but there were half a dozen other medics without any relevant background who submitted evidence (or their view of it) to the committee who, when asked if they had anything to declare, did mention membership of Christian or evangelical groups with an established position on abortion. I don’t care for an argument that rests on competing ideologies, so let’s look at Prof Wyatt’s evidence: because it has been hugely reported, and it goes against the evidence from a huge study called Epicure.
Epicure contains all of the data for every premature birth in England over the course of a year: one snapshot was taken in 1995, and one in 2006. Overall, it shows a modest improvement in survival for births at twenty-four weeks, but no significant improvement in the 10–20 per cent rate for births at twenty-two and twenty-three weeks.
For the next bit, you need to remember one simple piece of primary school maths. In the figure 3/20, 3 is the numerator and 20 is the denominator. If you have three survivors for every twenty births, then 15 per cent survive. For Epicure, the numerator is survival to discharge from hospital, and the denominator is all births where there is a sign of life, carefully defined.
There are two ways you could get a higher survival percentage. One would be a genuine increase in the number of babies surviving, an increase in the numerator: eight out of twenty live births survive, 40 per cent. But you could also see an increase in the survival percentage by changing the denominator. Let’s say, instead of counting as your denominator ‘all births where there is a sign of life in the delivery room’, you counted ‘all babies admitted to neonatal intensive care’. Now, that’s a different kettle of fish altogether. To be admitted to neonatal ICU, the doctors have to think you’ve got a chance. Often you have to be transferred from another hospital in an ambulance, and for that you really do have to be more well. Therefore, if your denominator is ‘neonatal ICU admissions’, your survival rates will be higher, but you are not comparing like with like. That may partly explain Prof Wyatt’s figure for a very high survival rate in twenty-three-week babies. But it’s not clear.
First, in his written evidence he said that the data was from a ‘prospectively defined’ study (where the researchers say in advance what they plan to collect). Then he was asked in the committee, when giving his oral evidence: ‘What was the denominator for that? Was that … 42 per cent survival at twenty-three weeks of all babies showing signs of life in the delivery room, or was it a proportion of those admitted to neonatal intensive care directly or by transfer?’ Prof Wyatt replied: ‘The denominator was all babies born alive in the labour ward in the hospital at UCL [University College London].’ This later turned out not to be true.
Then he was asked to send the reference for the claim. He did so. It was merely an abstract for an academic conference presentation three years ago. It did not contain the figures he was quoting. He then said he had done the raw figures on a spreadsheet, especially for the committee – bespoke, if you will – and sent them in. They are entered into the record as a memo, on 18 October 2007. They show new, different, but broadly comparable figures: 50 per cent survive at twenty-two weeks, then down to 46 per cent at twenty-three weeks, then up to 82 per cent at twenty-four weeks, then down again to 77 per cent at twenty-five weeks. (That bouncing around is because the raw numbers are so small that there is a lot of random noise.)
And the denominator? Prof Wyatt is clear: ‘I have provided the numbers and percentage of infants born alive at University College London Hospitals who survived to one year of age.’ The committee asked for clarification of this. Finally, on 23 October, another memo arrived from Prof Wyatt, entered into the record where all can read it. For the widely quoted 42 per cent survival rate at twenty-three weeks, Prof Wyatt admitted that the denominator was, in fact, all babies admitted to the neonatal intensive care unit. But in his new special analysis, giving this new ‘46 per cent survive at twenty-three weeks’ figure, the figures in the previous paragraph, he claimed the denominator was ‘all live births’. Has he undone a prospectively designed study, and retrospectively redesigned it? Or is this now a completely different source of data to the original reference?
I cannot blame Prof Wyatt for this, but his figure has taken on a life of its own. There may have been yet another mistake here, about the denominator. I don’t know. I’m quite prepared to believe that UCL may have unusually good results. But science is about clarity and transparency, especially for public policy. You need to be very clear on things like: what do you define as a ‘live birth’, how do you decide on what gestational age was, and so on. Even if this data stands up eventually, right now it is non-peer-reviewed, unpublished, utterly chaotic, changeable, personal communication of data, from 1996 to 2000, with no clear source, and no information about how it was collected or analysed. That would be fine if it hadn’t suddenly become central to the debate on abortion.