Would not Advise
We physicians seem to get this sort of question a lot on Real Self.
I, and I vouchsafe, all physicians are very cautious during pregnancy. We always look at the risk/benefit ratio when determining whether a drug should be used during pregnancy. Since the benefit is purely cosmetic, the risk easily outweighs any benefit. Thus, I would wait until you have delivered your baby. Then you can use Latisse, providing you will not be nursing.