Hi Julie,   It is difficult to say with certainty what the diagnosis of a rash is without a complete history and physical exam. The size, shape and appearance of a rash are crucial to generating a diagnosis.   The rash may be a form of hives and swelling (urticaria and angioedema) sometimes associated with foods, drugs, pregnancy and other triggers. There are also other possible causes of skin rash and swelling.   The fact that your niece is pregnant raises some other unique possibilities. There is a very itchy skin rash associated with pregnancy called Pruritic Urticaria and Plaques of Pregnancy (PUPPP). This rash occurs more often in the third trimester of first time pregnancies. The rash is usually intensely itchy. It usually resolves after delivery. I don't think swelling is associated with PUPPP.   It is important for your niece to have further follow-up with her doctor. An allergist may be helpful if she is not responding to treatment from her gynecologist or family doctor.   Best Wishes