When I was a kid and adult friends of my parents discussed trying to get pregnant, and the difficulty of correct "timing," I pictured a couple having sex while looking at a stopwatch, to determine how long they were having intercourse. 30 seconds (or a minute, etc., I didn't know!) too long or too short a time, and forget it! No pregnancy would result.
A childhood belief about getting pregnant

others believed things like this
- My parents told me I was found under a gooseberry bush which I thought odd for a long long time.— Kate
- I thought that a woman got pregnant kind of like catching a cold, by being around her husband for a long time.— No Name
- When I was first told about intercourse, I didn't believe it. How could peeing inside a girl make a baby?— Art
- When my parents would tell me they were going to Miami I'd ask "How long are you staying in Yourami"?— Christy F
- i used to believe that a elf familly lived on my window, long after a new my parents were Santa Claus— anna
- I uswed to believe that as long as someone lived to be 100, it was ok and you didn't have to be sad about it.Anon