That raises the old debate on whether the fertility of Aes Sedai women is extended and if so, how. There doesn't seem to be any reason why they couldn't carry a child safely up to menopause, but do they run out of eggs around the same age as other women or not? If their fertility is much extended, why would Yellows thought worth noting that Siuan and Leane (who were barely passed the limit for normal women) were again of "prime child bearing age"? Was it because as non-channellers then, they shouldn't be able to carry a pregnancy safely at their age despite still being fertile, but release from the oaths or stilling didn't negate the effects of slowing up to when they lost the Source - in effect making them physiologically much younger than their real age? Probably.

Of course, nothing excludes the possibility Ilyena was much younger than LTT and Lanfear. When you live up to 500-600 years old in top health, the usual points against a great difference of age within a couple, or raising a family beyond a certain age doesn't apply.