The only proof you have is of misogynists spreading malicious rumors.
Girls that young usually don’t know what they’re getting into, they might want to hold hands, to cuddle, perhaps a kiss or two. It’s probably a slightly older boyfriend who push and push and push for sex, until the girl gives in out of fear that he will otherwise dump her. None of the boys and girls have apparently received enough sex-ed to know how to protect themselves against STDs and unwanted pregnancies. That’s not the children’s fault, but the fault of adults, of parents, schools, society at large.
Young girls being promiscuous all by themselves won’t cause any pregnancies. It takes a boy/man to squirt his little swimmers into a vagina to cause a pregnancy. If you want to stop teen pregnancies, it’s the boys you have to address first.
It’s too bad only two of them (allegedly) had abortions. The bodies of girls that young aren’t ready to carry a pregnancy to term, or to give birth. The ordeal might well be fatal.