An astonishing photo of a newborn baby delivered still inside its intact amniotic sac is making the rounds online, months after Greek obstetrician Dr. Aris Tsigiris posted the image on the Facebook page of his medical practice on March 11.

Dr. Tsigiris, an OB/GYN operating out of Marousi, the suburban city northeast of Athens in which Greece hosted the 2004 Olympics, wrote in Greek that the healthy baby was delivered surgically by cesarean section, still surrounded by the amniotic sac filled with placenta.

The delivery was an "ultra rare" occurrence, said Dr. Tsigiris, in which the baby felt and behaved as if it had not yet been born even though it had already exited the womb.

During pregnancy, unborn babies float in the amniotic sac, a fluid-filled membrane that cushions, protects, and nourishes them as they develop.

The amniotic sac usually breaks when a pregnant woman goes into labor - an occurrence that's generally known as the "water breaking," with amniotic fluid gushing out of the birth canal, and signals that the baby is on its way.

In rare occurrences, like this one, the amniotic sac does not rupture on its own. Such a birth, in which the baby is delivered surrounded by all or part of the amniotic membrane, is known as an "en caul, or "veiled," birth.

Dr. Tsigiris said that such veiled births are more common, but still quite rare, in premature births. According to BabyMed, less than 1 in 80,000 babies are born with a caul.

Cesarean deliveries en caul might actually help protect fragile premature babies from pressure trauma in the uterus, according to a 2010 study that found such benefits to leaving the amniotic membrane intact until after removal from the womb.

Former farrier and animal behaviorist Neven Gibbs said that en caul births are also extremely rare among other mammals, requiring the mother to tear the amniotic sac herself if the offspring does not break it open with its own claws, hooves, or teeth.

While it might seem alarming for a baby to born surrounded by a watery bubble, Dr. Tsigiris said there is no danger of the newborn drowning inside the exposed amniotic sac, since the placenta continues feeding it nutrients and oxygen through the umbilical cord.

The baby immediately takes its first breath of air once the amniotic sac is ruptured, a simple surgical technique called an amniotomy in which a thin hook opens the membrane.

Dr. Tsigiris expressed awe at the sight of the baby enclosed in its amniotic membrane, saying in Greek that sometimes "nature transcends itself, leaving even obstetricians speechless," and thanking the Association des Sages Femmes du Cap Bon (Midwives' Association of Cap Bon) for its assistance.

Facebook users marveled at the sight, adding over 10,000 "likes" to the photo within 24 hours of its posting, according to a translation of the Greek site News 247. By June, it had gathered over 8,000 shares and almost 800 comments.

In medieval Europe, according to BabyMed, babies born with a caul had mystical associations of greatness, and midwives would often preserve the membrane for the mother to keep as an heirloom.

In literature, the protagonists of both Charles Dickens' David Copperfield and Betty Smith's A Tree Grows in Brooklyn were born with a caul -- in both novels, the membrane was preserved and sold for its purported ability to ward off drowning.

In 2011, reports the Daily Mail, the actress Jessica Alba gave birth to a daughter who was born en caul in an intact amniotic sac, inspiring her to name the baby Haven.

Source: Lin CH, Lin SY, Yang YH, et al. Extremely preterm cesarean delivery "en caul". Taiwan J Obstet Gynecol. 2010.