Congratulations! (on the three doxies and the baby! LOL!)
Connie my pup has been very wary of children, so I have tried to introduce her as slowly as I can (because I have four grandchildren! lol). I started with walks in the Park so she could get used to the noises from a safe distance, if we meet a child on the pavement I usually ask them to stand still (rather than approach her) and let her approach them if she is willing, curiosity usually gets the better of her and if she approaches to have a sniff she gets lots of verbal praise.
I have also asked some children to throw her a treat, a safe distance from them to reinforce a positive encounter. If your girl is frightened of children the last thing you want to do is pick her up as this will reinforce that there is something to be worried about, if you are worried keep calm ignore the child and walk positively past them. Connie has improved massively, she is still a tad nervous if they are running around being noisy so I make sure I am on top of it at all times, I never force her or overly comfort her, we just try to avoid anything I feel will be too stressful for her.
Do you have any friends with quiet / well behaved children that could help you out? There will be plenty of time to get your dogs used to the sounds of a baby while your little one is safe in the crib but they will need to be 100% by the time the baby is crawling so the sooner they get used to having them around the better.