What information does a OBGYN gather by performing a cervix exam to check dilation and effacement at 38 weeks? Is it needed, why not wait until labor begins?
My OB may induce labor at 40 weeks, I am 41 years of age first child.

A cervical exam is done to determine your dilitation. If you are going to be induced it assists in determining what form of induction is going to be used.