It's definitely an unstable term, and historically the age of consent has varied all over the place, not including cultures which practiced child marriages and thus didn't even bother with an age of consent. I believe the range today is 12-18, with some countries having a rather sensible system whereby there's a maximum age gap (2 or 3 years) between sexual partners if one is a minor. 9 is way under any age of consent that I know of. You could argue about whether a 15 year old understands the implications of sex and motherhood, but a 9 year old?