During the IVF process the woman will take birth control, then has to shoot herself full of hormones for weeks in order to encourage egg production. Then they harvest as many as they are able to. Usually the number of harvested eggs is around 10 or so. They eggs are tested and fertilized. After that, the fertilized eggs are tested again. If you’re lucky, you get 2-3 viable embryos. This process takes months. You have to freeze them to keep them viable.
How freezing embryos is legal in the first place is what I can’t figure out.