i would have said it was okay, as there is 0.5% alcohol in many de-alcoholized beers, but found this recent article:
http://www.jptcp.com/pubmed.php?articleId=408
obviously up to the mother, it's her baby, her responsibility, she must make the decision based on the latest research, but if it were me, i'd do all i could for the safety of my baby while i was pregnant.