The baby lambs - chosen due to physiological similarity to human infants - were placed into plastic sacks filled with lab-made amniotic fluid, with an oxygenator attached to act as a substitute umbilical cord.
Dr. Marcus Davey, one of the lead authors of the study, and a prominent figure in the area of Australian fetal research declared that the artificial womb developed at Philadelphia's Center for Fetal Research could significantly improve the outcome of premature births.
According to the research results published this week in the journal Nature Communications, the lambs' bodies continued to develop successfully inside the artificial womb, just as they would have done if they'd stayed inside their mothers' womb.
Researchers have designed a womb-like device that could allow premature babies to develop their lungs and organs in the critical few weeks that remain before they face the outside world. Electronic monitors measured vital signs, blood flow and other crucial functions. Doctors are also interested in adding some subtleties like audio recordings that simulate sounds a fetus would normally hear in the womb, like the mother's heartbeat.
Scientists believe it could be ready for human trials in three to five years. Complications along the way included issues with sepsis, lambs not surviving delivery and poor oxygenation.
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.
Researchers at Children's Hospital of Philadelphia created the artificial womb out of plastic. Instead, they're created to help preterm babies develop normally if their mother's can't carry them for a full pregnancy.
"This system is potentially far superior to what hospitals can now do for a 23-week-old baby born at the cusp of viability", Flake concluded.
Footage of the structure showed the young lamb wiggling in the clear device.
The team of researchers insist it is not looking to replace mothers or extend the limits of viability, but to find a better way to support babies born prematurely. It's going to take time before the external womb can be used on humans. After a series of prototypes, it emerged as a solution for premature animal babies.
Around 30,000 babies are born prematurely in the United States each year and many suffer for the rest of their lives as a result. They discovered that the artificially grown lambs had hearts and lungs that developed correctly without any abnormalities. One of the key medical frontiers is ensuring that premature babies can grow to childhood.
"I think it's realistic to think about three years for first-in-human trials", Alan Flake, fetal surgeon at the Children's Hospital of Philadelphia, said in a news release. "This could establish a new standard of care for this subset of extremely premature infants".