A lab would jump all over her and scare her more, not to mention the baby, unless it was a really old lab. Do speak to the husband about starting with a sensible choice instead of jumping on the first dog he sees. It sounds like he needs to stop and think that there will be a baby needing lots of attention along with the fear of dogs from the wife.

The first thing they should do before anything is go visit dogs. Visit a shelter where the dogs are behind bars. Talk to them about her situation and as she's ready they can bring out a very friendly, calm dog for her to pet and interact with.