Ahhh a baby - Congradulations - nothing more special !! (I'm jealous)
Here is the thing. Temporary anything does not make it in the mortgage world when your talking about income. Only because to be fair that stream of income could end tomorrow and then how would you make the payments. We sure don't want to put you in that terrible position.
BUT you have a job that you will return to - right?
So when you start back to work, that minute, it ends the disability - you'll be all set .... as long as you have your employer verify that you have returned and that your employment will continue indefinitely.
If you are really sure of the above, you could proceed to look and have everything in place so you could close as soon as you get back to work. They will probably make a condition on your loan that you prove you are back to work at your same job.
Happy Baby to you!