The research looked at babies born before 26 weeks gestation
Babies born at 23 weeks or earlier are no more likely to survive than they were a decade ago, a study has found.
The work by East Midlands doctors supports preliminary findings from national research published last month.
However, both studies show significant improvements in survival rates for babies born at 24 and 25 weeks.
The study is published in the British Medical Journal days after an MP launched a bid to cut the abortion limit from 24 to 20 weeks.
Nadine Dorries is tabling an amendment to the Human Fertilisation and Embryology Bill, which will be debated in the coming weeks.
Those who back a reduction in the abortion limit say improvements in the treatment available for premature babies mean it cannot remain at 24 weeks.
The BMJ research, by a team at the University of Leicester, compared babies born between 22 and 26 weeks of pregnancy in the Trent region between 1994-1999 and 2000-2005.
Professor David Field says his results are not surprising
Just under 500 babies were born in each period.
There was a significant improvement in survival for babies born at 24 and 25 weeks.
For 24-week babies, survival rose from 24 to 41%, while for 25-week babies it went up from 52 to 63%.
There was no change in the proportion of babies born at 23 weeks surviving, remaining at just under 20%.
And, of the 150 babies born at 22 weeks gestation over the course of the study, none survived.
The authors say their findings cannot be explained by changes in obstetric or neonatal resuscitation practice as similar numbers died in the delivery room in both time periods.
Of the infants born at 22 and 23 weeks, 58% died in the delivery room in 1994-9 and 63% in 2000-2005.
Limits of viability 'reached'
The team, led by Professor David Field, say this work is significant because it covered a wide area with 16 hospitals - rather than focusing on one hospital with a specialist neonatal unit.
What we've tried to do is give people the raw numbers and then they can make their own mind up
Professor David Field, University of Leicester
This, they say, means the data takes into account those babies who died on the labour ward - rather than only those who were admitted for neonatal care.
Professor Field said: "What we've tried to do is give people the raw numbers and then they can make their own mind up."
It appeared the limits of viability for the survival of premature babies had been reached, he said.
Writing in the BMJ, Professor Neena Modi from Imperial College London said the study was important because it provided the most up-to-date information on survival rates.
The findings echo early results from the decade-long Epicure 2 study, published last month, which also showed improved survival rates for babies born at 24 and 25 weeks, but not for those born earlier.
A spokesman for the Department of Health said: "This confirms that the current clinical evidence shows that there is no evidence of a significant improvement in the survival of preterm infants below 24 weeks gestation in the UK, since the upper time limit for abortion was reduced to 24 weeks in 1990."
Nadine Dorries said on her website said: "This report is the most desperate piece of tosh produced by the pro-choice lobby and it smells of one thing, desperation."
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