A mermaid baby birth is also known as an en caul birth, which is a rare birth event in which a baby is born still inside the intact, which is an unruptured amniotic sac and appears as if the baby is inside of a clear bubble or "veil," instead of the sac breaking first.
While a mermaid baby birth is often seen as being a magical or lucky thing in folklore, it's actually a normal physiological event where the sac's protective fluid filled membrane remains around the baby during delivery, which also requires that the caregiver or doctor to gently open it.
A mermaid baby birth is also distinct from the Mermaid Syndrome or sirenomelia, which is a serious birth defect where the baby's legs are fused, which resembles a tail.
Mermaid baby births or En Caul births are very rare and uncommon, and occur in less than 1 in 80,000 births.
With a mermaid baby birth the baby basically emerges from the mothers womb in a gelatinous and transparent sac that is filled with amniotic fluid, like for example a water filled balloon.
Mermaid baby births are generally very safe, although a doctor will carefully remove the sac after the birth of the baby.
The reason for the mermaid baby birth is a result of the amniotic sac, which is what protects the baby and nourishes the baby in the mothers womb, simply not rupturing or breaking like it should before or during delivery.
In many cultures a mermaid baby birth like in Irish Culture, Scottish Culture, African Culture and Asian Culture, it's considered to be a sign of good fortune, destined greatness and spiritual protection.