Inside what look like oversized ziplock bags strewn with tubes of blood and fluid, eight fetal lambs continued to develop — much like they would have inside their mothers. Over four weeks, their lungs and brains grew, they sprouted wool, opened their eyes, wriggled around, and learned to swallow, according to a new study that takes the first step toward an artificial womb. One day, this device could help to bring premature human babies to term outside the uterus — but right now, it has only been tested on sheep.
It’s appealing to imagine a world where artificial wombs grow babies, eliminating the health risk of pregnancy. But it’s important not to get ahead of the data, says Alan Flake, a fetal surgeon at the Children’s Hospital of Philadelphia and lead author of today’s study. “It’s complete science fiction to think that you can take an embryo and get it through the early developmental process and put it on our machine without the mother being the critical element there,” he says.
Instead, the point of developing an external womb — which his team calls the Biobag — is to give infants born months too early a more natural, uterus-like environment to continue developing in, Flake says.
The Biobag may not look much like a womb, but it contains the same key parts: a clear plastic bag that encloses the fetal lamb and protects it from the outside world, like the uterus would; an electrolyte solution that bathes the lamb similarly to the amniotic fluid in the uterus; and a way for the fetus to circulate its blood and exchange carbon dioxide for oxygen. Flake and his colleagues published their results today in the journal Nature Communications.
Flake hopes the Biobag will improve the care options for extremely premature infants, who have “well documented, dismal outcomes,” he says. Prematurity is the leading cause of death for newborns. In the US, about 10 percent of babies are born prematurely — which means they were born before they reach 37 weeks of pregnancy. About 6 percent, or 30,000 of those births, are considered extremely premature, which means that they were born at or before the 28th week of pregnancy.
These infants require intensive support as they continue to develop outside their mothers’ bodies. The babies who survive delivery require mechanical ventilation, medications, and IVs that provide nutrition and fluids. If they make it out of the intensive care unit, many of these infants (between 20 to 50 percent of them) still suffer from a host of health conditions that arise from the stunted development of their organ systems.
Of course, lambs aren’t humans — and their brains develop at a somewhat different pace. The authors acknowledge that it’s going to take more research into the science and safety of this device before it can be used on human babies. They’ve already started testing it on human-sized lambs that were put in the Biobags earlier in pregnancy. And they are monitoring the few lambs that survived after being taken off the ventilator to look for long-term problems. So far, the lambs seem pretty healthy. “I think it’s realistic to think about three years for first-in-human trials,” Flake says.
“It’s so interesting, and it’s really innovative,” Rogers says. “To be able to continue to develop in an artificial environment can reduce the many problems caused by simply being born too early.” Rogers adds that not every facility has the resources or expertise to offer cutting-edge care to expecting mothers — a problem that the Biobag won’t be able to solve. “We know there are already disparities after preterm birth. If you have access to high-level regionalized care your outcomes are often better than if you don’t,” she says.
For Flake, the research continues. “I’m still blown away, whenever I’m down looking at our lambs,” he says. “I think it’s just an amazing thing to sit there and watch the fetus on this support acting like it normally acts in the womb… It’s a really awe-inspiring endeavor to be able to continue normal gestation outside of the mom.”