Oh my god, you are so incredibly stupid. Its literally impossible to get pregnant before you hit puberty--the whole basis of puberty is beginning the process of reaching sexual maturity, which is the basis for reproduction. Some people flower earlier than others, some later than others. Hitting puberty doesn't always start with growing breasts and hair in intimate places.
Also, incest happens a lot. And very young girls who, from a biological standpoint, have no place reproducing get pregnant all the time. Its a fucked up world we live in, sweetheart.