May 8, 2008 09:00 AM
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Reader Karen asks:
One of my favourite sci-fi conceits in the Vorkosigan works of Lois McMaster Bujold is the uterine replicator. Sticking a fetus in a regulated jar until it's come full term and I can get my new baby boy, girl or hermaphrodite without all the vomiting, constant peeing, strenuous pushing, pooping on the operating table, and possible endangerment to life, reproductive organs and blood sugar levels sounds like fucking bliss. When can you get that to me?Given the risk - and many months of what can charitably be termed "inconvenience" - what are the alternatives to signing up for nine months of incubator duty? Let's find out.
The design (and I use the term very loosely) of the female reproductive system leaves a lot to be desired. Having a baby has been a dangerous proposition for most of human history. Historically one out of every hundred births resulted in the death of the mother. Modern health care can reduce that mortality ratio to nearly 1 out of every 10,000 births, but it is not (and never will be) entirely safe.
While our large craniums and upright posture have their advantages, they make traveling the birth canal an ordeal. If you don't believe me, compare the size of the infant cranium (black rectangle) to the pelvic inlet (white rectangles) for humans and a few of our primate cousins.
This is why they call it "labor".
The geometry does more to engender sympathy than confidence. Artificial wombs have appeared variously in science fiction, from Aldous Huxley's Brave New World to Star Wars and The Matrix.
Adorable and energy-effective!
The Force may have a strong effect on the weak minded, but good luck trying to convince a few million surrogate mothers that bringing a Stormtrooper to term would be a joy.
These are not the wombs you're looking for.
Iain M. Banks' Culture novels, on the other hand, tend more towards "natural" births, though the mother's body has been extensively bioengineered for safety and choice. Culture citizens have conscious control over their own fertility, and can store a fertilized egg in stasis for years - their pregnancies have a snooze button.
Whether you'd prefer a new and improved reproductive system installed as a replacement for your own or external to yourself (say, next to the washing machine), there are a few recent advancements bringing it a step closer to reality. An emulsified liquid blood substitute called perflubron has had some success used as a replacement for amniotic fluid for premature babies in respiratory distress. It's not a complete replacement for the complex stew of hormones, lipids, and proteins normally present in the amniotic fluid, it is at least a promising way to get oxygen into developing lungs.
Believe me, the mouse is as surprised as you are.
Even if we had a tank filled with a healthy, fully-functional amniotic replacement, we'd need an organ to make use of it. Researchers at Cornell University's Center for Reproductive Medicine and Infertility have built primitive tissue engineered uteruses using cells donated by infertile patients. Human embryos (left over from in vitro fertilizations) successfully implanted upon these multilayered constructs and gestated for 10 days. After that the experiments were ended - full-term experiments with mice have had very mixed results, but even being able to implant upon such a device is a serious achievement.
Once these engineered uteruses are perfected, we'll presumably have the option of surgically implanting them. Uterus transplants in animals as large as ewes have demonstrated that they can, at least, be removed and re-implanted without loss of function. Attempts to do the same in humans have thus far failed, but we haven't stopped trying.
Combine a fully-functioning uterus with a setup like Tokyo's Juntendo University's and instead of transplantation you could achieve ectogenesis - fetal development outside of the human body. Their bioreactor could bring goats to term (not always successfully) by pumping in nutrients and removing waste. Of course, the goats still needed to do most of their developing in a natural womb, but combine this apparatus with a uterus engineered from your own tissue, and maybe you'd have initial implantation and the tail-end of pregnancy covered.
As surprising and weird as this all is, we're still many decades away from a safe, human uterine replicator that can bring an embryo from conception to zeroeth birthday party. Even once we've sorted out the technical aspects of the womb itself, we'll have to deal with what the rest of the mother's body contributes to development. Hormones have already been mentioned, but baby also borrows mommy's disease-fighting machinery. Our replicator will require nearly complete endocrine and immune systems, too.
All in all, I'd take a serious look at adoption.
Terry Johnson is a biology researcher at UC Berkeley and io9's resident biogeek. If you have a question you'd like Terry to answer, email him at: tdj@io9.com.
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