I'm sure you can successfully sell anything from coffee to yoga classes that helps with fertility. Just takes the right pitch and the right mark.
I've read some peer reviewed research as well but most of that is focused on outcomes and genetic testing of IVF embryos rather than natural fertilization. I get the impression that fertility isn't something that's well-studied outside of really generic health indicators like weight and age. And a lot of fertility information seems to focus on ages 20 to 35. They seem to assume that after that age you've given up on starting a family or that you already have one.