Try to create a routine starting from now that you will keep upon the arrival of your baby besides getting your dog to get accustomed to the baby's smell, etc. Try to not pay attention as much as you used to towards her and create a playtime and personal attention for her that you will keep upon baby's arrival. The reason for not paying as much attention is that upon your baby's arrival, it is going to happen. You will not be able to lavish as much attention on your yorkie as you do at the moment so you do not want her to associate it with your baby's existence so it is important you start as early as a month or two before baby comes home. Also, prepare your dog to not let her on the couch as before because when your baby comes home, expectantly you will be sitting with baby on the couch. You want to let the dog have the idea that baby is of a higher rank in the pack. This is practised until baby is older and you can trust your dog with the baby then she can go on the couch whenever she wants.
I do not have a human child yet but I have read a few articles about human baby arrival issue. All the best to you. I am sure it will work out fine. Good luck
