A synthetic placenta that holds steady for 14 days on the bench

The synthetic placenta is the heart of Amnia. If it doesn't work, nothing else matters. So the milestone we want to share this month is a real one: on the bench, our latest membrane oxygenator held stable gas exchange for 14 continuous days without degradation, clotting, or intervention.

Here is exactly what that means — and what it doesn't.

What we tested

The synthetic placenta does the job an infant's own lungs can't yet do: it oxygenates blood and removes carbon dioxide through a gas-permeable membrane, mimicking the exchange a natural placenta performs. Ours is a closed, sterile loop driven by the pressure of the developing heart rather than an external pump — the same principle that made pumpless designs a breakthrough in animal studies elsewhere in the field.

For this run, we circulated a blood-analog fluid through the device under physiological conditions and measured three things continuously:

• Oxygen transfer and CO₂ clearance across the membrane
• Pressure drop across the circuit, our early-warning signal for clotting
• Membrane integrity — no plasma leakage, no fouling

The result

Across 14 days, oxygen transfer stayed within 3% of its day-one baseline. Pressure drop was flat. There was no measurable membrane fouling. In earlier generations, performance fell off within days as the membrane surface degraded; a new anti-thrombogenic surface treatment is what carried this run.

Two weeks of stability on the bench is the threshold we set ourselves before moving toward more demanding, whole-system testing.

What this does not prove

This is the part we care about most.

• This was a bench test, not a living subject. A blood-analog under

controlled conditions is a far kinder environment than real circulation.

• It is one subsystem. A working placenta is necessary, not sufficient —

the amniotic loop, thermal control, sensing, and the AI guardian all have to work together, continuously, for far longer than 14 days.

• It says nothing about safety in a child. That bar is years and several

regulatory phases away. See our regulatory roadmap for how each of those gates works.

What's next

We're now integrating this membrane into a closed-loop rig alongside the amniotic-fluid system, so the two can be characterized as one system rather than two parts. We'll report what we find — steady or not.

If you want these milestones as they land, they go out to the waitlist once a month.