Well... I wouldn't do it. If your dogs are well-behaved, it sounds unnecessary. Right before a baby comes is a time to tighten up the pack, not scatter it. You don't know the effects of the place on the dogs, it may be mixed. Then add a new baby into the mix ... I think that's too much upset for the dogs.
I had two newfies when my first child was born. Honestly, they were in no way a burden or a problem for me. In fact, the opposite. It was a comfort to have them around during the early days of motherhood, days which can often be, paradoxically, quite lonely. It was nice to have a pair of newfies there.
Now my gals were older, both seniors. If I had two young dogs, and they needed lots of exercise and adventures off property, I would perhaps consider doing a dog spa/day care for them in the first couple of weeks. Just because your hands will be full w/ the baby. I'd spend your money on that.
We recently had Winston at a sleep away spa while my mom was here post-surgery. It was a lovely spot and the dogs slept with the owner and were taken on two hikes off leash a day. It was just right for W. and if you could find something like that in your area, that might be fun for your puppers.
I don't know if I'd time it right when the baby got home. It might be better for them to be there during the arrival and early days so that they bond and don't feel kicked out because of the baby.