With the opening of the two-child policy, more and more pregnant women are coming to the clinic, and more and more pregnant women are coming to the clinic with skin diseases. PUPPP: pruriticurticarial papules and plaques of pregnancy, translated as pruritic urticarial papules and erythematous plaques of pregnancy, is a common skin disorder during pregnancy, with an incidence rate of 1/130-1/300, and most of them occurring in the first trimester of pregnancy, in the late stages of gestation (average onset time of 35 weeks). Occasionally, it develops in the early postpartum period. Pathogenesis The etiology of PUPPP is unknown. Excessive weight gain during pregnancy has been documented in patients with PUPPP, and the incidence is increased in multiple pregnancies. Although this latter finding is currently debated, a recent analysis of a large sample found that the incidence of multiple pregnancies was 10 times higher in affected women. It is therefore believed that rapid stretching of the abdominal skin in late pregnancy can lead to connective tissue damage and induce allergic reactions. Other theories include increased progesterone levels associated with multiple pregnancies and peripheral chimerism, which promotes increased skin vascularity and collagen damage. Clinical features The onset is abrupt, with 90% of patients having lesions on the abdomen. Typical lesions do not involve the umbilical region, but may expand symmetrically to include the buttocks, proximal upper extremities, and the dorsum of the hands within a few days. The initial lesions are limited to the stretch marks, the face is not involved, moderate or severe itching, epidermal exfoliation is rare, tiny blisters may appear, but will not form large blisters. Occasionally, target-shaped or ring-shaped lesions appear. It resolves naturally within a few weeks after delivery and does not affect maternal or infant health. However, usually the greatest maternal distress is the itching, which severely interferes with sleep and rest. PUPPP has no known correlation with other dermatologic or systemic diseases. It does not increase the risk of disease in pregnant women or fetuses. Differential Diagnosis 1. contact dermatitis 2. drug rash 3. urticaria 4. viral rash 5. pemphigus vulgaris in pregnancy Treatment There are many contraindications to treatment due to the pregnant woman, and treatment guidelines are derived mainly from experience and small sample case studies. Most patients are effectively treated with strong topical corticosteroids and oral antihistamines, but occasionally women require systemic corticosteroid therapy. Since remission occurs within 7-10 days after birth, conservative treatment is more reasonable and consists of topical glycerite lotion, compounded bitter ginseng lotion, or topical lotion with boiled broth of ginkgo, chirimen, bupleurum, and bitter ginseng.