Being pregnant or advertising that your car contains a baby signals that you are valuable to the continuation of the species, and your survival is essential. Flagging up that you are past child-bearing age does exactly the opposite and is likely to have the opposite effect to what you intended.
Maybe that is a bad thing, but our instincts are deeply embedded, and won't be changed by a badge.
If you need special treatment because of the menopause, then get medical advice, and thank your lucky stars that you are still alive to need it - in previous centuries you would probably not have lived long enough to have the luxury of the experience.