A childhood belief about getting pregnant

when i was about 5 or so, me and my mom were talking, and somehow the subject became babies, birth, things like that (i still didnt know how babies were made though). i also dont know how this came up, but my mom told me that my babysitter was old enough to have a baby. my babysitter then was like...15 or so, and i was shocked. before this conversation, my mom had always told me that people could only have babies after they got married (believing in no pre-marital sex) and my 15-year-old was definitely not married. of course she was talking about menstruating and stuff, meaning she was just capable of having a baby. i had no clue about this, so i was SOOOOO deathly afraid that when i got to be her age, that i would just magically become pregnant, just out of the blue. i wondered how so many girls managed to stay un-pregnant because this could just happen to anyone when you were old enough...oh, how naive i was...