Well any kind of livestock breeding is, or can be. I have had a few goats returning to service, so having to trundle back to the male, but from then on it was always ok. Had a couple of cases of pregnancy toxeamia, but treated with Propylene glycol drenching and goats made full recovery.
I find sheep harder, in that my goats are handled evey day, can be loaded to get to the vets with minimal stress etc etc. You see much quicker if things are not right, even though I check the sheep every day you wouldn't necessarily see the results of a miscarriage and also PT is much more difficult to spot...