For those downvoting, consider biology. The average age of menarche is 12. By 22 that's 10 yrs of youth. The flower of her age. Do you think a women's fertility being lower than her peak is the flower of her age? Her youth? Ridiculous. If a flower has started to wither then it's past its prime, it's visibly in its decline.
Menarche isn't peak fertility though. That's like arguing that a 13 year old boy is in his prime and ready to breed because he's capable of ejaculation.
Menarche may make pregnancy possible (in fact - it's always possible; there have been cases of very young girls getting pregnant), it doesn't mean that pregnancy is at its most likely or safest. Fertility continues to increase for several years after that, while the risks of pregnancy complications go down. According to the below, it would seem that fertility actually reaches its peak around 18 (and that doesn't mean it immediately starts falling from there).
The average age of menarche in the United States is about 12.5 years.[34] In postmenarchal girls, about 80% of the cycles are anovulatory (ovulation does not actually take place) in the first year after menarche, 50% in the third and 10% in the sixth year.[35]
I really just don't get the obsession some of you have with age. Are younger women generally more attractive and fertile? Yes. But statements like "a man always prefers the younger woman" (right, because with each passing day after her mid-teens, a woman progressively shrivels up, to the extent that even the prettiest 25 year old is like a hag compared to a plain 15 year old? Humans don't age that fast!) or that a 22 year old is 10 years past the "flower of her age" are wildly extreme and also factually incorrect.
The point that girls in their mid-teens are in fact women and eligible for marriage according to Canon Law and biology has been demonstrated. I think the issue people are having is not with that statement, but with the continual focus and fixation on the youngest women possible. It doesn't come across well.
We could even make this objective and compile a list of actresses or other public women we could easily compare across ages. I guarantee I could show that, besides little to no decline in fertility, there is little to no decline in appearance until the late-20s, and that an obsession with teenagers' apparent superiority to 20somethings is wholly misplaced.