This is actually pretty common in underdeveloped countries (which is odd, because Brazil is actually pretty developed.) It happens a lot in the backwaters of China... basically, if some couples have a girl instead of a boy, they'll stick needles in to try and kill it via infection so they can try again (or just not have to take care of it... Apparently it's worse to put the kid up for adoption then it is to MURDER IT). Autopsy's are pretty uncommon on children and needles don't leave much of an entry wound, so the parents usually get away scott free.