Wow, I can understand why people aren't jumping out of their seats to attack this question - I can see it becoming controversial... especially since I'm going to say no. I think it's quite problematic. I am by no means a sexist - I'm far closer to being a feminist than being on the other side of the fence - but there are a lot of reasons why putting her in the field would be a bad idea. For the sake of brevity, I'll just give you one, and let others chime in.
In all reality, the truth is that while she might be fully there mentally (and perhaps even emotionally), she's not at her physical peak while pregnant. This is a job where mistakes can cost lives, and if she can't keep up - or perhaps she's cautious at the wrong time because of the child - that could put another person's life in jeopardy. I absolutely believe the job should be kept for her, but I don't think she can adequately fulfill her duties while pregnant.
I won't even get into the societal reaction if something were to happen to her, but that would also likely be an issue.