Andrew Lansley and Nadine Dorries, perhaps unsurprisingly, don't read this blog...

During the second reading debate of the Human Fertilisation and Embryology bill, there was an interesting exchange between Andrew Lansley (the shadow health secretary) and Nadine Dorries MP, on the recent research into survival rates of extremely premature infants.

Lansley talks about the Trent study, that showed no increase in survival rates for infants born before 24 weeks:

The authors also report that no babies born at 22 weeks survived. Like other studies, they suggest that this might represent the limit of viability. I cannot say whether they are right, but I note that, of 150 babies born alive at 22 weeks over the whole period of the study in Trent, only 24 were admitted to intensive care. In the latest period, 2000-05, only nine were admitted to intensive care. From my point of view—I am not a scientist, but I can read statistics—in order to draw any conclusion from such a small number of cases, one would need to assess why those babies were being born so prematurely. Were they failing to thrive? Were they twins or other multiple births? Were they suffering from a genetic defect?

Abortions at 22 weeks would be of a foetus that was otherwise healthy, unless they were carried out on the specific ground of a prospective abnormality or handicap of the child concerned. So while such a baby would require intensive care, and doubtless very large numbers might not survive, I do not regard that study as providing conclusive evidence that a baby cannot be sustained at 22 weeks.

I would personally be loth to move from the principle of linking the time limit for abortion to the viability of the foetus. That is where it was established in 1967; it has moved over time. It is arguable, but I would argue personally that the evidence would support a further reduction—in my view, to 22 weeks—in order to ensure a prospective legal framework that could accommodate improving medical science.

To which Dorries has this to say:

I am sure that my hon. Friend is aware of other studies—for example, in University College hospital, London, and in other countries—showing that if poorly babies who are born prematurely receive immediate good neonatal care from a specialist dedicated team of staff, the outcomes are very much better. University College hospital figures are much better than those emerging from the Trent study. One conclusion from the Trent study is that anyone going into premature labour should go to University College hospital and not to the Trent region.

This is exactly what you can't conclude from a comparison of the Trent and University College studies. It's difficult to compare the studies, because the Trent study includes all infants 'alive at the onset of labour', while the UCLH study included only infants that were born alive. Another issue with the UCLH study is that the numbers of infants admitted to the neonatal intensive care unit varies wildly between the different time periods of the study. This may be because the number of subjects is so small, leading to a large amount of statistical noise. Or it may be because those time periods are not directly comparable, perhaps due to differing policies on which infants should go to the neonatal intensive care unit through time.

And Lansley replies:

My hon. Friend may have gathered from what I said that I am effectively arguing that in circumstances where neonatal intensive care was provided to all such babies born at 22 weeks and where the foetus was otherwise healthy—or rather the baby was healthy at that stage—the prospects for survival at 22 weeks may well be far greater than suggested by the negative view expressed in the study from Nottingham and Leicester. It is not for me to say any more than that, but I think that it provides a basis for reducing the limit—albeit, in my view, by just two weeks.

In fact, the Trent study (Nottingham and Leicester) is more likely to give an accurate idea of the prospects for survival, because it is a multi-centre study (including 16 hospitals in the Trent health region) while the University College study concentrates on a single hospital. So the Trent study is less likely to be confounded by selection bias, and includes a much larger number of subjects, leading to statistically more robust results. It's difficult to see how Lansley can come to the conclusion that the study 'provides a basis for reducing the limit', given that it shows there has been no change in survival rates before 24 weeks since the early 1990s. Happily, the lead author of the Trent study, Prof. David Field of Leicester University, has pointed this out.

There may be other reasons for seeking a reduction in the limit for abortions, but the Trent study is not one of them. To suggest otherwise is simply to misrepresent the research.