I used to believe that getting pregnant was like inflating a beachball. The Husband inserts his member into the Wife, and while pumps, pumps, and pumps some more, her belly slowly rises. This continues for as long as necessary. They might pause for a break, with them rubbing the belly going, "You reckon that's big enough?". The Wife then carries around a full-size belly for 9 months, to give the baby enough room and time to develop.
A childhood belief about reproduction

others believed things like this
- I used to believe that when a woman was pregnant, she fed the baby with a tiny spoon through her belly button.— Marie
- When I was younger I thought that when a woman was pregnant she would feed her baby through her belly button!— Hennie
- I used to think that if i touched my belly button it would unfold and my belly would be inside out forever. Anon
- When I was three I used to believe that cow and horse are wife and husband.— xenia
- I used to think you had to put it in a girls belly button to get them pregnant.Anon
- When I was little I thought that a honeymoon was when the Husband and wife went to the moon and eat honey.— AmAnDa