Hope for the tiniest preemies

WASHINGTON — Researchers are creating an artificial womb to improve care for extremely premature babies — and remarkable animal testing suggests the first-of-itskind watery incubation so closely mimics mom that it just might work.

Today, premature infants weighing as little as a pound are hooked to ventilators and other machines inside incubators. Children’s Hospital of Philadelphia is aiming for a gentler solution, to give the tiniest preemies a few more weeks in a womblike environment.

The researchers created a fluid-filled transparent container to simulate how fetuses float in amniotic fluid inside mom’s uterus, and attached it to a mechanical placenta that keeps blood oxygenated.

In early-stage animal testing, extremely premature lambs grew, apparently normally, inside the system for three to four weeks, the team reported April 25.

“We start with a tiny fetus that is pretty inert and spends most of its time sleeping. Over four weeks we see that fetus open its eyes, grow wool, breathe, swim,” said Dr. Emily Partridge, a CHOP research fellow and first author of the study published in Nature Communications.

Human testing still is three to five years away, although the team already is in discussions with the Food and Drug Administration.

“We’re trying to extend normal gestation,” said Dr. Alan Flake, a fetal surgeon at CHOP who is leading the project.

Increasingly hospitals attempt to save the most critically premature infants, those born before 26 weeks gestation and even those right at the limits of viability — 22 to 23 weeks. Extreme prematurity is a leading cause of infant mortality.

One of the biggest risks for very young preemies is that their lungs aren’t ready to breathe air, she explained. Doctors hook preemies to ventilators to keep them alive but risk lifelong lung damage.

Flake’s goal is for the womblike system to support the very youngest preemies just for a few weeks, until their organs are mature enough to better handle regular hospital care like older preemies. The device is simpler than previous attempts at creating an artificial womb.

The study didn’t address longterm development. Most of the lambs were euthanized for further study that found normal organ development for their gestational age. One was bottle-weaned and is now more than a year old, apparently healthy and living on a farm in Pennsylvania.