A caul baby is a baby that is born while still inside the amniotic sac.
The amniotic sac is the fluid filled membrane which protects the fetus from the womb.
In a caul birth the baby is born while having part of the amniotic sac or membrane covering the baby's head or face which gives the baby an appearance of a veil.
The doctor can remove the membrane.
Caul births are not as rare as an en caul birth.
In an en caul birth the baby remains inside the unopened amniotic sac.
Usually when you're about to go into labor, your amniotic sac bursts which is when your water breaks.
Sometimes, you can go into labor and the sac doesn't burst, causing the baby to be born en caul and completely inside a jelly-like bubble.
Being born en caul is something that happens by chance.