Artificial womb helps premature lamb fetuses grow for 4 weeks

Extremely premature lambs have been kept alive in an artificial uterus for four weeks. The system uses a fluid-filled plastic bag and could be used for premature babies within the next three years. 

“We’ve developed a system that, as closely as possible, reproduces the environment of the womb and replace the function of the placenta,” says Alan Flake at the Children’s Hospital of Philadelphia in Pennsylvania, who led the study.

“It is fascinating,” says Neil Marlow, at University College London. “People have been trying to do this for ages.” But he says the system will have to undergo years of testing to be sure it is safe for babies.

Flake and his colleagues developed their system with babies in mind. Being born extremely prematurely is the most common cause of death in babies. Infants born at 22 to 24 weeks, instead of the full 40 weeks, have only a 10 per cent chance of survival, says Flake.

Those that survive are vulnerable to a host of disorders, and can develop lasting disabilities, such as poor vision or hearing or cerebral palsy. “They have very immature organs,” says Flake. “They’re simply not ready to be born yet.”

Babies supported in incubators are prone to infections, for instance, and the gas ventilation that is needed to help babies breathe can leave them with lung damage.

But the plastic bag system provides a sealed environment that should protect a fetus from infections. To mimic the environment of the uterus, the team fill their bags with fluid comprising water and salts.