I took "when a man and a woman love each other very much..." too literally -- because that was all I got to hear! I thought that simply by being married (and, therefore, in love), one was risking getting pregnant at any time, regardless of any actual interaction with the couple. It all just happened by chance.
A childhood belief about getting pregnant

others believed things like this
- I always hear Manic Street Preachers 'You Love Us' as 'You Love Arse'.— Lou
- I used to believe that the B-52's song "Love Shack" was actually "Love Shark!"— Natalie
- I used to believe that women could only get pregnant once they were married and it just sort of happened Anon
- I thought making love meant making someone fall in love with you!— Brainhead
- I used to think the song "love the one you're with" was called "love the one, your win. — Glowworm
- When I was little I used to think that as soon as you were married the woman automatically got pregnant.Anon