Preprepared sandwiches with cold meat and cheese etc are a bit of a no-no as you have no way of telling whether the cheese has been pasteurised or whether the cold meat etc is crawling with listeria. Likewise with fruit/salad that has been cut - no way of telling how long ago it was cut and whether there is a listeria risk there. You're better off providing whole fruits like strawberries, cherries and grapes, maybe with some dried fruit and nuts thrown in for variety?

A better option for pregnant women is hot savories (make sure they are piping hot) like small quiches, mini pizzas etc, or even a hot soup (in paper cups) with bread rolls etc.

HTH