Rottie and baby

Question
I have a 4 year old rottie, who I have had since she was 8 weeks and she has never shown any real aggression towards anyone. She acts like a baby most of the time.  I also have an 8 year old lab and the 2 get a long great.
My question is how do I prepare my rott for a new baby.  I am 3 months pregnant and I want to make sure that there are no jealous issues when the new baby comes home.  When I or my husband pay more attention to the lab,my rott will try to push her way in between us or try and sit on him. Are there steps I can take to prepare my rott for the new baby?

Answer
Buy a realistic looking toy baby doll.  Carry it around and show lots of attention toward it while ignoring your dogs.  Do this for very short intervals after which you ask both dogs for a trained behavior and heavily food reward.  I gather neither of your dogs has been socialized to children or infants, not a good thing.  For this you might require the help of a certified applied animal behaviorist.  I suggest you consult one.  Meanwhile, when the baby is born, have your husband bring a blanket home to introduce the infant's smell to your dogs. However, under no circumstances, at any time for any reason, are you to leave any infant or young child alone with any dog.  Babies and dogs, on the same floor, do not mix.  No matter how sweet the dog, babies smell a certain way, have no pheromones (making them sexually unidentifiable) and make high pitched sounds and often behave unexpectedly.  No dog can be trusted alone with a baby or young child, at any time.