Very difficult as in very costly and lots of fertility type treatments, or very difficult as in very unlikely, but just keep trying and it might happen on its own?
Some fertility treatments we are not morally comfortable with. Others are just too expensive for something that may not even work. (Not as expensive as adoption, but adoption was a guaranteed eventuality.)
We plan to keep trying until I start to get a bit too old for it.
On the plus side, I never have to take birth control again.