, also known as polymorphic eruption of pregnancy (or PEP), is the most common rash that exclusively affects pregnant women (eczema also is common but it can affect anyone). PUPPP usually occurs in the third trimester. The rash appears like hives
within the stretch marks and can spread over the thighs, buttocks, breasts, and arms. It lasts an average of 6 weeks and resolves on its own 1 to 2 weeks after delivery.