Lichen planus is a common skin disease. It can be caused by a variety of reasons: infection with bacteria, viruses (especially the simple vesicular virus), enzymatic bacteria, and protozoa related. When a pregnant woman is infected with urticaria, the virus infects the fetus via the placenta. Therefore, for the health of the fetus, pregnant women should prevent infection with rubeola. Preventive measures: 1. Adjust the diet. Pregnant women with allergies must adjust their diet from the fourth month of pregnancy onwards, avoiding as much as possible foods that can easily trigger allergies and eating more fresh, protein-rich foods such as: fish, cow’s milk, eggs, soybeans, meat, cereals, etc. 2. Establish good healthy habits. Don’t overwork or stay up late, try to get enough sleep; avoid keeping pets at home such as cats, dogs, birds, rabbits, rats, etc. Avoid smoking and being in second-hand smoke and dirty air, and avoid excessive use of cleaning agents. 3. Avoid stimulating the skin. The mother-to-be should reduce the amount of cleaning products on the belly, and after bathing, apply some lotion on the waist and abdomen, and avoid wearing stuffy and non-breathable clothing. 4.Reduce contact with allergens. To prevent or treat allergic diseases, the main method, is to reduce the opportunity to contact with allergens. Because allergies are closely related to heredity, prevention should start from pregnancy; if a woman induces allergies in pregnancy, the fetus’ immune system will recognize this allergen and have a memory of it, and if the baby encounters the same allergen after birth, it will immediately have an allergic reaction.