I think there are none that are a big no-no while pregnant- what you need to watch for is how your skin reacts as it may be more sensitive.
have you had acne before or is this just a pregnancy thing? if it's the first time, start off with something gentle and work your way up if it doesn't work. if you've had skin probs before, try what worked last time- just watch out for reddness, dry skin and inflamation and if any happen stop using that face wash.
I found last time that the acne was worse in the 1st and 2nd trimester but cleared up by the 3rd
and, old wives tale, acne means a it's girl