Scientists have created an artificial or “external womb,” which someday could be used to save human babies born extremely prematurely—at a gestational age of less than 28 weeks.

A study, published in Nature Communications, involving six fetal lambs, found that the new device can effectively enable extremely premature fetuses to develop normally. The premature lambs were kept alive while floating inside the transparent, womb-like “biobag” for about four weeks after birth. This is especially heartening because lamb fetuses have been shown by previous research to be good models for human fetal development.

“Doctors said that the pioneering approach could radically improve outcomes for babies born so early that they cannot breathe, feed or fight infection without medical help,” notes Hannah Devlin in the Guardian.

About 1 of every 10 infants born in the United States was born preterm in 2015, according to the Centers for Disease Control and Prevention. In 2013, about 36 percent of infant deaths were due to causes related to prematurity. Racial and ethnic disparities also persist. In 2015, for example, the rate of premature birth among African-American women was 13 percent, about 50 percent higher than the rate of 9 percent among white women.

The biobag—which was placed in a dark, warm room where researchers could play sounds of the mother’s heart—consists of a clear plastic bag filled with synthetic amniotic fluid. Outside the bag, a machine attached to the umbilical cord functions like a placenta, providing oxygen and nutrition to the blood while removing carbon dioxide.

Image credit: The Children’s Hospital of Philadelphia

“We’ve been extremely successful in replacing the conditions in the womb in our lamb model,” says Alan Flake, a fetal surgeon at Children’s Hospital of Philadelphia who led the study. But Flake quickly ruled out an entire gestation taking place externally.

“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,” Flake told NPR’s Rob Stein. “There’s nothing but the mother that’s able to support that period of time.”


Image credit: Partridge et al, Nature Communications

A developing baby goes through important growth throughout pregnancy, including in the final months and weeks. For example, according to the CDC, “the brain, lungs, and liver need the final weeks of pregnancy to fully develop, and there is a higher risk of serious disability or death when the baby is born early.” Babies who survive a premature birth may have breathing problems, feeding difficulties, cerebral palsy, developmental delay, vision problems and hearing impairment.

A medical intervention like the biobag could prevent some of these risks and allow further development but it could also eventually blur the line between a fetus and a baby, worries Dena Davis, a bioethicist at Lehigh University: “Up to now, we’ve been either born or not born. This would be halfway born, or something like that. Think about that in terms of our abortion politics,” she said.

– Danielle Bizzarro

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