Unless you skipped sex ed class, you probably have at least a basic understanding of how babies are made. An egg (ovum) needs to be fertilised by sperm during a precise window in the menstrual cycle for life to happen.
Sexual intercourse provides optimal conditions for reproduction. But that doesn’t mean that every pregnancy happens this way. There are also examples of women conceiving in extremely rare circumstances that you’d expect to be impossible.
Via anal sex
Via oral sex (and one very heated argument)
Splash pregnancies
Double pregnancy
These examples are of course extremely rare – so you probably don’t need to worry too much. But if you aren’t looking to get pregnant anytime soon, be sure to use contraception.