Artificial Wombs

Janet DiPietro is the world’s leading expert on what it’s like to be an embryo. A developmental psychologist at Johns Hopkins University, she is one of the few scientists to have closely studied the womb as an ecosystem. In recent experiments, DiPietro and her colleagues attached monitors to the skin and belly of pregnant women. They had expected to find that the child within responded to its mother’s moods. Earlier research had shown that fetuses react almost instantly to changes in maternal position or emotions—with stillness. DiPietro speculates that this is the way the fetus learns to understand its mother and her body and how she reacts to noise and other stimuli.

But in work published last year, she found that the instruction is hardly unilateral. Fetuses teach their mothers, too. “We found that the fetuses were moving when the mothers weren’t even aware of it, and were giving the mother a little emotional jolt. They were, in effect, training her to pay attention to them.” Since much of this movement comes at night, they were also giving her a foretaste of sleep deprivation, apparently knowing deep within their DNA that she might as well start getting used to it.

“The fetal environment is more than just hormones,” DiPietro says. “You can’t simply add titrates of this or that hormone or protein and re-create the womb.” An embryo gestating outside its mother “will wind up being different than that same embryo [would be] had it developed the natural way.”

Women who have borne children understand this instinctively. Any woman who has lain in the dark watching a heel-shaped bump move across her belly knows that a sensibility is growing within, that the child is becoming itself even while still a part of her. The success of adoption shows that this interaction isn’t necessary for parental bonding. But is it essential in certain immeasurable ways to the infantile brain and body, to a baby’s later ability to touch, attach, and love?

As Liu pursues the science of hormone levels and gene expression, she too worries about the ineffable. In 2001, after her earliest experiments with human zygotes were publicized, she was inundated with calls from infertile women begging to become test subjects. Overwhelmed by the response and by her own unwonted realization that,
as she says, “this work could have great social impact,” she halted the artificial-womb experiments for a full year, resuming only after reaching certain decisions.

“I don’t want to make a womb for the convenience of women who don’t want to be pregnant,” she says. And she declines to discuss the uses that anti-abortion groups might make of her results. “I want to make a womb that would be a replacement organ,” she says, that would be implanted in a woman whose endometrial tissue was donated, that would fully re-create the rich, dark wilderness of a healthy female reproductive system.

But as we all know, intentions don’t mean much once an innovation is released. Liu thinks she and her team should have a viable mouse womb in 5 to 10 years. A human model will take longer—“10 years, maybe, or a little more,” she says, assuming that restrictions on fetal testing are lifted or eased. “It could take as much as 50 years, but I’m very hopeful that this is possible.” Her voice is soft. “It will be helping a life, a baby, helping parents. Those are good things, and that’s all I can be thinking about right now.”

Gretchen Reynolds lives in Santa Fe, New Mexico, and is mother to a son, Max. This is her first feature for Popular Science.