There are less than 1 out of 80,000 babies who are born with a caul. There are no wonders to the fact that born with a caul superstition could be termed as a rare occurrence. It is rated to be something special it does become a cause of terror among the would be mothers. But you need to consider it as part of the harmless process related to the birth.
When it is a birth caul, it is a piece of amniotic sac that is attached to the head of the new born baby. In the rarest of cases it could be termed as an En caul birth that looks like a thin and filmy membrane. You could term this condition as born with a veil. The caul tends to emerge when the sac breaks away from the gestation period and this is during the process of birth. The doctor would peel off the caul without any major issue and in the rare cases if the caul is adhered to the head of a baby care needs to be taken so that it does not stick to the head of the baby.
The Roman midwives did steal cauls and then sold them off to the lawyers. They are of the opinion that if they owned them they could win cases. This superstition did exist to other European countries. There were some others that a portion of the powdered caul could go on to cure malaria. Say for example in the country of Dalmatia if you placed caul under the bed of someone it would make their passing off easy. In Belgium the caul was only considered to be lucky if you placed it under the bed. The coal miners did carry on cauls with them to ward off chances of any explosion.
There are many superstitious that have originated in Great Britain. In 1889, a miracle caul emerged though in later cases it was termed as something exceptional. A baby was born with a caul and this was removed without accident and then placed on the side. Writing in it did go on to spark a debate. But then the doctor did realize that he had committed a mistake. Still though the word of intervention was that it was stuck.
There are some others who believed that being born with a caul was a symbol of good luck. It would prevent someone drowning for the rest of their life. This is as long as you are in possession of the caul. There was an ante code in 1939 where a boy drowned after his mother threw away the caul. This is regardless of the belief that a caul was immune to drowning there were many families who sold cauls to families for a good deal of money. There are many famous caul babies and the name that strikes is Napoleon.
To conclude you are bound to have super natural powers when you are a caul baby.