In the US study, six premature lambs were used to test the most recent version of the device, which was originally designed as a glass tank. Picture:

London – An artificial womb that could keep premature babies alive outside the body has been developed by scientists.

The plastic-bag like device, known as a "biobag", aims to replicate conditions in the womb and has already been successfully tested on lambs.

It could be available for trials on critically ill babies within three to five years. Unlike conventional incubators, the biobag surrounds a premature baby with a liquid that is similar to the amniotic fluid that would encompass it naturally.

The biobag also allows the baby to breathe through its umbilical cord, which is connected to an oxygenator, just as it would inside its mother.

This aims to prevent the often fatal lung infections that many premature babies suffer in an incubator because they are forced to breathe through their tiny and underdeveloped lungs.

The baby is able to digest nutrients from the laboratory-made fluid.

The liquid environment is also said to be easier to keep sterile than a conventional incubator.

Pro-life campaigners are currently calling for a review of the 24-week abortion limit, citing the increasing likelihood that a baby born before the abortion limit could be viable.

At present, babies born at 23 weeks have roughly a one in three chance of surviving in the UK, although life threatening complications are common. Those that do survive have a 90 percent probability of suffering chronic lung disease or other effects of being born with immature organs. The new system aims to increase the likelihood that a baby born between 23 and 28 weeks will be able to develop healthily. 

In the US study, six premature lambs were used to test the most recent version of the device, which was originally designed as a glass tank, remaining in the "womb" for up to one month. Lambs are usually born after five months. The animals "breathed" and swallowed normally, opened their eyes, grew wool and developed properly functioning nerves and organs, said the researchers in the journal Nature Communications. Doctors said the lambs, which are now one year old, "appear to have normal development in all respects".

Dr Alan Flake, of the Children’s Hospital of Philadelphia, said: "Our system could prevent the severe morbidity suffered by extremely premature infants.

"These infants have an urgent need for a bridge between the mother’s womb and the outside world. If we can develop an extra-uterine system to support growth and organ maturation for only a few weeks, we can dramatically improve outcomes for extremely premature babies. This system is potentially far superior to what hospitals can currently do for a 23-week-old baby born at the cusp of viability."

Professor Colin Duncan, of Edinburgh University, said: "Researchers supported the growth and development of extremely premature foetuses within a bag of fluid where the foetus pumps its own blood through an artificial placenta. This is a really attractive concept and this study is a very important step forward."