Why does “in whelp” mean?

[Derbee]

Hoping someone can help. Currently waiting for a puppy, and the breeder said “as soon as we know the bitch is in whelp, you can come and meet the dogs). Does that mean pregnant? Or already given birth?

Very confused, and no amount of googling is giving me a clear answer! Anybody know?

It means pregnant, so I assume she means once she knows the bitch is pregnant, you can meet the parents. Perhaps once they know how many puppies are expected, they invite the next x number of people on the waiting list to see the parents?

Thanks, that makes sense.