I used to believe that, rather than giving birth, when the baby was born it would climb out the collar of whatever the mother is wearing by using a ladder. (I imagined a small ladder like one from a bird cage).
A childhood belief about giving birth

others believed things like this
- I used to think that the expression "The former or the latter?" was actually "The farmer or the ladder?" — Fitzwilliam
- When i was litttle i used to believe that if a had a long enough ladder a could touch the sky.— Sarah Howell
- I believed that the ladder on the back of a trailer/rv led up to a swimming pool.— marilese
- I believed travel trailers had a pool on top because the curved ladder was the same.Anon
- i used to think when you had an orgasm you were giving birth— splooger
- Until I was five, I used to think that women gave birth to baby girls and men gave birth to baby boys— Cassidy K