Bubble boy: Baby born inside intact amniotic sac

"Born in the caul" is a phrase that's connected with a lot of cross-cultural myths and superstitions — babies born in the caul are supposed to be destined for lives of fame and fortune (or, possibly, misfortune and grisly death, depending on which legends you're listening to). Biologically, though, it refers to a baby that's born with part of the amniotic sac — the bubble of fluid a fetus grows in inside the uterus — still attached. Usually, a piece of the sac is draped over the baby's head or face. These are called caul births, and they're rare. But, about once in every 80,000 births, you'll get something truly extraordinary — "en-caul", a baby born inside a completely intact amniotic sac, fluid and all. There's a photo of a recent en-caul birth making the rounds online. The photo is being attributed to Greek obstetrician Aris Tsigris. It's fascinating. But it's also pretty graphic, so fair warning on that. (If the sight of newborn infants and blood gives you the vapors, you might also want to avoid most of the links in this post, as well.)

Check this out. I mean, seriously. That's awesome.

There doesn't seem to be a lot of information on the details of this particular birth, but, most of the time, when a baby is born this way it's also born premature. Sometimes, really premature. There are case reports in medical literature of babies being born en-caul at 23 weeks, 6 days gestation, which, for context, is a little over half the weeks you'd want a baby to gestate. Fetuses aren't large or well-developed enough to even be able to clearly tell their sex on an ultrasound until about 20 weeks gestation.

The premie connection is probably more than coincidence. For one thing, the smaller the fetus, the more space the sac around it has to ballon outward and come through the birth canal intact. What's more, there's evidence that being born en-caul has a protective effect for premature infants. Nobody is exactly sure why. But it might have something to do with the physical mechanics of birth, which, I'm sure you're aware, can be a little rough on both mother and baby. Premies born en-caul essentially come with their own cushiony air bag, which might protect them from physical injuries that could otherwise be life-threatening. So, in that sense, babies born en-caul really are lucky. Just not in the way the ancient legends would have you believe. In fact, in 1975, a newborn survived for 25 minutes outside the uterus, but inside the fluid-filled amniotic sac, not breathing air, and turned out completely healthy.

Speaking of legends of the caul, back in 1952 The Yale Journal of Biology and Medicine published a manuscript by Thomas Forbes, which collected literary and documentary references to caul-related superstitions dating back to Roman times. I wanted to share one particularly fun story from Forbes' account. This refers to a caul birth, rather than an en-caul birth, so the amniotic sac wasn't totally intact. Instead, just a part of it was draped over the newborn baby's head.