If she is healthy without pregnancy complications and is able to perform the necessary functions, I would much rather have a fit young woman in the exit row, rather than some of the folks I have seen there.

On one of my recent flights there was a 70-ish couple in the exit row. The FA asked for confirmation that they were willing and able and the man said to his companion, " don't worry honey, we will help you". The FA took this as "yes" and walked away.