There are many causes of urticaria, postnatal urticaria itchy at night may be related to contact with allergens, physical factors, mental and endocrine factors. 1. Contact with allergens: there are many allergens, common pollen, animal dander, dust, dust mites, etc. If there are allergens indoors, postnatal urticaria itchy at night will occur. 2. Physical factors: physical factors include friction, pressure, cold, heat, etc. If the temperature is too low at night and no warming measures are taken, it will also induce or aggravate urticaria, resulting in itchy skin. 3. Mental and endocrine factors: postnatal hives at night itchy may also be related to mental and endocrine factors, including mood swings, nervousness, depression and so on. Postpartum hives itchy at night, you should seek medical examination, clear diagnosis, and cooperate with the doctor standardized treatment.