

You are still not addressing the difference between “a portion of individuals will be capable of having a viable pregnancy at this age” with “adulthood”.
So as mentioned earlier, some nine year olds have survived pregnancy, especially in the last few decades. The mortality rate is absurd, and pretty much all neurological hallmarks of adulthood are nowhere near complete… but they do fit your definition perfectly. They can conceive healthy offspring.
Would you call them adults? Would you lower the age of consent to 9? Assuming in good faith your answer will be “no” then you must, by definition, introduce other conditional aspects to “adulthood” that go beyond the ability to sustain pregnancy, which was my point.
I’m replying to a comment claiming several states have the age of consent set at 14. Your reply makes zero sense.