Hi Carla and a huge Congrats !!
We have a huge pack at our home and from the snap (avatar?) ours are a bit bigger than your fur kids. In the past 8 years my daughters have gifted us with 5 grand children who live with us ( 5 more who don't) anywho... we have a fail proof way to deal with the new baby issue.
1. We include the dogs in everything BEFORE the baby arrives. They go in the nursery, they smell the bedding and the gifts after parties... all of which are accompanied by tidbits from the showers !!
2. We talk endlessly to the dogs,,, do you like this paint, will this be soft for the new puppy ? Does this rattle sound great ? Isn't this a great room ? Does this music feel calming to you??
3. I have my daughters lay with the hounds...hubbies too (when there was one 
) They talk about the baby while petting the dog(s) Asking the dog "will you help take care of our baby?" They assure the hound "this is going to be Your baby too "
4. As the date gets closer and expectant mom gets crankier.. I INSIST they cuddle , hug and invade the dog's space... (why you ask?? they baby will too so let's start now when there isn't an infant and when they can control and reward the dog).
5. If , and this will sound a little , I don't know wierd, your milk begins to come in ...do not push the dog away when they scent it. They are going to be curious, and let's face it they have a way better sense of smell than we do. Just allow them to figure it out. Don't let them be a nuisance, set boundries... if this seems icky think of it this way baby has an almost unlimited supply of "treats" he/she only has to cry.... You are simply letting pup realize it's not a prime rib !! They can learn by a few gentle sniffs and know it's not for them and that's okay.... later this will translate to bottles and other baby treats.
6. when you get really close again remember your dog was gifted the sense of smell. Try hard to avoid shutting them out .
7. While in the hospital, have hubby bring home baby items.... used blankets, even used diapers to start the familarization with baby. Don't freak out if there are some nibbles or strong nose bumps, they are excited not mean or aggressive. Take this as an opportunity to teach them EASY, GENTLY..
8. Have family talk to the dogs about the baby !! They like knowing the WHOLE pack is involved.
9. When the baby and you come home have dad run LOVING interferance, don't allow the pups to jump and bounce off of you. Sniffing is normal but only what you extend for them. Praise should be calm and consistant with the baby's name involved... " I know I smell funny I went to get "?"
As I mentioned I have a LOT of babies in our home, my hounds have acted as superior heart monitors to the premie and as contented guardians to the rest, all of the , hounds and grands adore each other and contact is a daily thing .
best of luck and let us all know what the baby is and how things turn out !!
Bonita of Bwana