Diclegis?

I saw my OB for my first appt yesterday and I told her that my morning sickness was pretty rough and consistent (though not actually vomiting).  She automatically prescribed me Diclegis and said it was perfectly safe. I thought this was supposed to be taken only when women were so sick they couldn't keep things down. Curious to know other people's thoughts on how bad things should be before taking this and also what you may have heard about the safety of this drug.