Born Under the Caul

While all humans develop inside an amniotic sac, only a rare few are born with part of it enveloping their face. These membranous veils protect us in utero, but what does it mean when a newborn is covered in one at birth? In this episode of Stuff To Blow Your Mind, Robert and Christian explore what a birth caul is and the many superstitions and omens attached to their presence.

As is sometimes the case with genetic anomalies and mutations, sirenomelia or "mermaid syndrome" conjures certain fanciful images that have nothing to do with the traumatic effects associated with the actual medical anomaly. Sirenomelia is so named because the birth defect involves the apparent fusing of the legs into a single lower limb, with the out-turned feet often resembling fish fins. The defect also commonly affects the kidneys, large intestines and genitalia. The condition sometimes affects the spine, brain and lungs as well. According to, this rare condition occurs when a fetus develops only one umbilical artery (which pumps blood from the fetus to the placenta) and one umbilical vein (which returns blood to the fetus), while normal fetuses develop two umbilical arteries and one umbilical vein. The altered arrangement causes less blood and nutrition to reach the lower body, leading to the fused limbs and underdeveloped array of organs.