I don't think it helped me conceive because I actually started it post conception but I think getting in touch with my body throgh similar methods to what you do in yoga class did help me conceive. It's a good idea. And yes, the yoga will make you more aware of your breathe which in turn will allow you to bring up more mucus on command but not necessarily during class
There's something called prenatal yoga. Not sure if there's preconception yoga but there's a belief that if you really want to get pregnant to surround yourself with pregnant people, thoughts, information, etc. so if you're up for it sign up for one of these classes... just be prepared for the question - so when is your baby due? also you will likely chant positive affirmations for you and the baby. You could think of it as your baby's soul instead of the baby inside you.