The limits of viability for the survival of premature babies appear to have been reached, a team from the University of Leicester has concluded.

Their new study appears in the British Medical Journal online the week before Parliament is due to debate the time limit on abortion. The increasing survival of very premature babies has led some people to suggest that the limit should be lowered from the present 24 weeks.

However, a team led by Professor David Field, using data from the Trent region of the NHS, suggests that in the past 12 years there has been no change in the survival rates of those born before 24 weeks. They looked at data for all babies born before 26 weeks’ gestation who were alive at the onset of labour from 1994 to 1999 and from 2000 to 2005. The study involved 16 hospitals with more than 55,000 births a year.

They found that despite more than half the babies born at 23 weeks being admitted to intensive care, there was no improvement in survival in this group over the 12 years of the study, and only 18 per cent (12 out of 65) survived out of hospital. Importantly, during the 12-year period, care for the 150 babies born at 22 weeks remained unsuccessful, and none survived to be discharged.

There were, however, significant improvements in the survival of babies born at 24 and 25 weeks. Of 497 babies admitted to intensive care in 2000–05, 236 (47 per cent) survived to discharge compared with 174 of 490 (36 per cent) in 1994–95. The Trent region is reasonably representative of Britain, say the authors.

The MPs Dr Evan Harris, Jacqui Lait and Chris McCafferty, who are leading the campaign to defend the 24-week time limit for abortion, said: “This research completely blows out of the water the spurious claim of antiabortionists that the threshold of foetal viability has reduced from 24 weeks since the early 1990s.

“This reinforces the emerging findings from the nationwide EPICure 2 study which has also found no improvement in survival below 24 weeks when comparing all births in England in 2006 with 1995. The medical research literature is very clear that it is these whole-pop-ulation studies that provide the most reliable indication of survival rates.

“In contrast, single hospital figures, usually unpublished, that are cited by antiabortion groups are misleading because they preferentially select those cases which are likely to survive in the first case.”

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