How do you treat pink eye in a pregnant woman?

"Pink eye" means a lot of different things to different people. The original term has been linked to epidemic shipyard conjunctivitis in the middle of the 20th century, but probably goes much further back than that. So, it is a vague enough term that any answer to your question is incomplete. This could be caused by bacteria, viruses, allergies, contact lenses, internal diseases, systemic infectious, or chemicals—just to name a few.

Treatment varies from nothing at all, to cool compresses and non-preserved artificial tears, to topical antibiotics or even systemic treatment depending on the condition. You need to be seen and evaluated by an ophthalmologist to sort out these issues. Almost certainly, this can be treated successfully without endangering the fetus, but this needs further evaluation.