Artificial Wombs

Artificial wombs have figured for generations in fiction, feminist theory, abortion debates and even the wistful imaginings of women far advanced in pregnancy. In Brave New World, the 1932 book by Aldous Huxley, babies grew in tubes. In 1970 Shulamith Firestone wrote in The Dialectic of Sex: The Case for Feminist Revolution that artificial wombs should be developed to free women from “the tyranny of their sexual-reproductive roles.” More recently, the exhausted working-mother heroine of the novel I Don’t Know How She Does It assures a younger female colleague that she, at least, will be relieved of the tedium and career-torching effects of pregnancy, thanks to emerging baby-in-a-box technology. Science has been playing catch-up to these fantasies: In 1963, researchers put miscarried fetuses in oxygen chambers and added a watery fluid. It didn’t work.

The closest approximation of an operational machine-womb was created about five years ago. In experiments at Juntendo University in Tokyo, an acrylic box was filled with a liquid similar to amniotic fluid. A goat embryo, removed by cesarean section after four months of normal gestation, was placed in the chamber and its umbilical cord hooked to tubes connected to an artificial placenta. Most of the kids died, but a few survived up to three weeks, reaching full term for a goat. None was without deformities or lung problems. The experiments are no longer under way.

Which has left the field to Liu. She and two of her colleagues, both men, have been refining their artificial womb bit by bit. They’re developing liquid formulas that are incrementally closer to the fluids within an actual mammalian uterus, although developing the perfect mix of blood, hormones and proteins—and precisely adjusting it during the course of a pregnancy—is so far impossible. Minuscule differences in amniotic fluid have been found, in other labs’ experiments, to produce notable differences in the resulting offspring.

In Liu’s most recent experiment, she surgically implanted one of her artificial mouse wombs in an adult mouse, and the fetus inside lived about 19 days. (In earlier experiments, fetuses survived in external wombs for up to 17 days. That’s roughly equivalent to 37 weeks of human fetal development, although fetuses appear to develop slower in artificial wombs than in real ones.) But invariably, each mouse embryo, more than 150 to date, died. One reason, Liu believes, is that the snaky vines of blood vessels that should link the tiny bodies to the womb’s surface wither or fail to develop at all. Starved of blood, the embryos shrivel.

To rectify this, Liu’s colleague Weidong Wang has been studying the expression of a gene, called murine AGPAT, that seems to stimulate blood-vessel formation within the womb. If you block that gene, the embryo can’t implant fully and grow, which may explain why some women—in whom this gene is missing or malfunctioning—miscarry. Force the gene’s expression, on the other hand, and you
get a jungle of blood vessels, a fecund clot of veins. The work may have implications for cancer treatment. Block the gene’s expression, and you could disable a tumor’s ability
to create new blood vessels for itself, causing a slow self-strangulation. “There’s overlap between research into fertility and oncology,” Wang says. “The beginning of life and the end of life. We deal with both in this lab.”