Viability in the Coming Era of the Artificial Placenta

Artificial Placenta

With the New Year in full swing, let’s jump into the abortion issue, but not in the usual way that you might hear about it. In politics and ethics, intentional termination of a pregnancy is often debated in terms of the rights of the mother versus the rights of the mother. In some religions –which tend to come into the public discussion a lot—rights of the father are cited frequently too. The topic could not be more emotional and potentially divisive. But I’m bringing it up here, because it relates to a technology that we’ve started to discuss, namely the artificial womb. Specifically, I’m talking about a step in the direction of the artificial womb and that step is the artificial placenta.

First, here’s little bit on terminology. If we talk about artificial womb or an artificial uterus, the idea is equipment and procedures that would enable development of a human, from fertilized egg to full-term infant, completely outside of the mother for the entire 40 weeks. That’s called ectogenesis, a word invented in 1924 by J.B.S. Haldane, a British scientist, science communicator, and visionary. In his essay, Daedalus, Haldane predicted that most babies would be born through ectogenesis by 150 years later, in other words 2074.

We may have an artificial womb by then, or it may take a little longer, but we’re taking a step with the artificial placenta. In the past couple of years, scientists at the University of Pennsylvania have solved a series of technical issues. These include how you can give oxygen to a fetus outside the womb and remove carbon dioxide, not through the lungs, but directly into and out of the blood. They also include how to maintain the correct pressures in different blood vessels and how to protect against infection, while also being able to examine the developing fetus with ultrasound –all outside of the mother.

They’re testing the technology on fetal lambs, which are somewhat bigger than humans of an equivalent age. Similar research is happening in other countries, but the UPenn researchers have an investigational device exemption (IDE) from the US Food and Drug Administration, which may soon advance the experiments humans born prematurely around 22-25 weeks gestational age. That’s when they are considered viable, because the lungs can be made to work, but the survival chances are very dim.

Using a technology called Extracorporeal membrane oxygenation (ECMO), the newborn’s blood can be supplied with oxygen, while carbon dioxide is removed. This eliminates the need to force the lungs to start working way too early. Instead, the lungs are left collapsed, so the fetal respiration situation is maintained. The UPenn researchers have done this successfully with fetal lambs of a weight and size matching a human fetus at 23-24 weeks gestation. However, since lambs are bigger than humans, this corresponds to the developmental level of a human fetus of only 16-17 weeks. Now, in humans, such an artificial placenta would be used no earlier than gestational age when a premature infant could live (but usually doesn’t) with standard treatments that involve the lungs. That means 22 weeks or so.

But, since the lamb studies imply that the same machine could support a younger infant, the limit will likely be only legal, not medical. This means that eventually somebody, somewhere, might use it on a human that would otherwise not be even close to viable based on the lungs.

In such a case, the limit of viability would be pushed backward. And since the whole basis of the abortion issue depends on viability, how would politicians and judges handle the fallout?

David Warmflash
Dr. David Warmflash is a science communicator and physician with a research background in astrobiology and space medicine. He has completed research fellowships at NASA Johnson Space Center, the University of Pennsylvania, and Brandeis University. Since 2002, he has been collaborating with The Planetary Society on experiments helping us to understand the effects of deep space radiation on life forms, and since 2011 has worked nearly full time in medical writing and science journalism. His focus area includes the emergence of new biotechnologies and their impact on biomedicine, public health, and society.

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