Yes, it happened to me twice, the first was on the wedding night. When I had protected sex, nothing happens. However, when i had unprotected sex(which i never agreed to), I'll get pregnant. My cycle is not regular n I didn't calculate. Both are unplanned pregnancies, so I was scared of getting pregnant again cos I didn't plan to hv kids. I hv no fear of being pregnant now, as my marriage is on the rocks.
Like what nelle mentioned, don't count on no protection when u are not ready for kids. It can create problems later if there is no mutual agreement. I just wish I was more assertive then.