If anything I would suggest showing with your actions that her changing body and sexuality are nothing to be ashamed of. For example if she needs tampons or pads don't act weird about buying them. It also depends on the questions as it might just be that your wife will have a better understanding of whats's being asked. In that case I think maybe instead of just saying ask your mother and leaving her to imagine why you don't want to answer say something like "your mother knows more about that and would be a better person to ask" That way she understands that she is going to her mother simply because she is the most knowledgeable on the topic. I say this because although my own mother tired to talk to me about some things I could always feel how uncomfortable it made her and if anything that messed me up the most.