The leader of the Roman Catholic church in England and Wales is due to ask ministers to lower the 24-week limit on abortion.
More babies born at 24 weeks are surviving
He is expected to argue that technological advances are helping babies to survive at an earlier age making the current laws outdated.
The BBC news website asks two experts in neonatology how care of premature babies is improving.
Dr Huseyin Mehmet, is a research scientist at Imperial College, London.
He also does work at Hammersmith Hospital on brain damage in premature babies.
"I've been working at Hammersmith for some 13 years and when I first started working there it was quite unusual to send a foetus home at 24 weeks, which is just under six months pregnancy.
"Now we can send many children home who are born at 23 weeks gestation. In terms of viability, those children who go home are obviously alive but there may be some questions about quality of life."
HOW NEONATAL CARE HAS CHANGED
Wider use of steroids in mothers likely to give birth early, which helps development of the foetus
Better understanding of the best time to deliver
Improvements in ventilation and temperature control
He said data from a large national study called the Epicure study have indicated that about 20% of infants born alive at 24 weeks go home to a relatively normal life.
He added that our understanding of the development process hadn't changed but our ability to care for premature babies in hospital had improved.
"For example, we understand better the causes of prematurity, we understand how to treat these babies better in hospital and keep them alive.
"Therefore we are dealing with them in a more medically efficient way to send them home in a physically healthy condition."
But he stressed: '"In my opinion I think that 22 to 23 weeks is pretty much the limit of what nature will allow us to do with current technology."
"There are some very very preliminary experiments going on in Japan where people are toying with the idea of artificial wombs.
"If babies are born before [22 weeks] it may may be possible in the distant future that we can nurture them in an artificial womb until they are developed enough to survive in the outside world but with current technology, realistically we should be thinking about 22 to 23 weeks as the limit."
Professor Kate Costeloe, professor of paediatrics at Queen Mary, University of London, is one of the leaders of the Epicure study which was established in 1995 to determine the chances of survival and later health status of children born at less than 26 weeks.
"We have got generally better at looking after babies before birth so they are born in better condition and we have made some progress in looking after them in neonatal units.
"There's much more widespread use of steroids given to women likely to deliver very prematurely," she said.
"That not only promotes maturation of the lungs in the early part but it also reduces the likelihood of having bleeds in the brain and bleeding into the brain is a very high risk factor for later severe neurodevelopmental problems.
"And we're slightly better than we were at judging when to deliver babies.
"Once they are born, we're better at keeping them warm - hopefully fewer babies are getting very cold at birth - and we're slightly better at ventilating them.
"In epicure only about 10% survive at 23 weeks - there hasn't been a change in the number that are surviving - and they have very severe problems.
"But the data we have from some centres is suggestive that survival is improving at 24 to 25 weeks."
She added that it was as yet unknown whether more of these babies were then going on to have severe problems.
"That's always a worry, that as we're getting better at helping babies survive, you are helping babies who will have bad complications and end up with severe disabilities."