A lamb in an artificial womb from a team at the Children’s Hospital of Philadelphia. (Image: The Children’s Hospital of Philadelphia)

It may look like a glorified Ziplock bag, but the artificial womb could one day save the lives of the thousands of babies born every year prematurely.


For the second time, researchers announced this week that they have successfully incubated lambs born before reaching full term in an artificial ‘womb.’ In findings published this week in The American Journal of Obstetrics & Gynecology, researchers from the University of Western Australia, Australia’s Women and Infants Research Foundation, and Tohoku University Hospital in Japan reported that several lambs continued to grow during a week-long incubation period in an “ex-vivo uterine environment” dubbed “EVE.” They appeared healthy when later delivered.

The artificial womb system, “EVE,” used to incubate lambs. IMAGE: Women and Infants Research Foundation


It’s not the first time that researchers have successfully used such a system to incubate preterm lambs. In April, researchers at the Children’s Hospital of Philadelphia used a similar system to incubate premature lambs for a record-breaking four weeks. Lambs have a shorter gestation period so the 105- to 115-day-old premature lamb fetuses in that study were the equivalent of about 23 weeks in a human. The hope is that such systems could help babies born as early as 22 weeks. Each year in the United States, approximately 30,000 births are critically preterm, meaning babies are born before 26 weeks of a full 37-week gestation period.

The system in the new study relies on a fluid-filled plastic bag to keep the lambs alive. A bath of artificial amniotic fluid fills the bag to mimic conditions inside the womb. An external oxygenator fills in for the mother’s placenta, allowing gas exchange of CO2 and oxygen in the fetal blood. Like the Children’s Hospital study, the Australian and Japanese researchers relied on the fetal heart to power the womb, ensuring that developing hearts and lungs don’t get overloaded and giving those organs a chance to develop normally.

Before the April study, the maximum duration a lamb fetus had survived in an artificial system was 60 hours, and those animals experienced brain damage.

The success—using a fetal-powered system for the second time—is an important step towards having something that could actually be tested in human babies. Such a system would be a vast improvement over the current treatment, which is to place premature infants in an incubator and rely on devices like ventilators to assist their still-developing organs.


Such new technologies, though, will also inevitably raise new ethical questions. Recently, one researcher pointed out that the availability of artificial womb technology could threaten a woman’s right to an abortion, since in the US the right hinges in part on whether a fetus is viable. The technology could also result in premature babies that survive, but have lifelong impairments or conditions, raising questions of when it would be appropriate to use such technology.

There is still much work to be done before artificial wombs are ready for humans—if they ever are at all. Researchers have said it will be at least five years before trials are even a possibility, if not more. But it is a future we are inching closer to every day.