Q: my menses has been late for 3 weeks. and i'm certainly not pregnant, i'm only 15! what's happened? i'm not sexually active (:
A: It's not uncommon for your period to be regulating itself, if you are not sexually active. I'm 20 and I still skip a month every now and then. If you are sexually active, you can become pregnant at ANY age, as long as you've had your period.