Well it isn't a medical issue. Sorry if that sounds blunt, but it isn't. I get that it's the most important thing in your life right now, but you need some perspective.
Would be ok to pick up a colleagues workload because they wanted to have a baby?
Sometimes I think that we are losing perspective on the purpose of work. Some people seem to think that a job is like a hobby and you can just piss around, taking days off whenever you feel like it.
"Mental health day"
"My kid has a dentist appointment"
"My dog is sick"
"I feel depressed"
"I'm off due to stress"
Take IVF out of the question and imagine asking your boss this . .
"Hey boss, can I have every Wednesday off for the next six weeks, no not annual leave, I just want to do something, and if I can manage it, in a little while, I'll also demand nine months off, with pay. And when I come back I'll need lots of other random days off without notice. Basically, for the next three years, you'll never know when/if I will come into work.
I still demand that you pay me though.
Is that ok?
Thanks.
I'm sure you'll get the time off. But if your work can do without you all that time, do they even you there in the first place?