I don't know about age, per se. But perhaps it's because younger students tend to not have children, and, certainly in my cohort, that has been the route of a bit of quite a bit of insecurity.

I have to say i am glad that i have had a child, only because my Mentors seemed to quietly sigh when they find out i have had no nurse training, so if i had the double wammy of not having had a child too, i'd feel even more conspicious!

But saying that, IMHO becoming a great MW is more about having a the personality/caring/communication skills -something that won't fundamentally change nevermind which side you are of well functioning pelvic floor muscles!!