The clinical manifestations of psoriasis (commonly known as psoriasis) combined with pregnancy during pregnancy and puerperium, especially the effects of psoriasis and medication on the prognosis of perinatal infants, have their special characteristics. Three cases of psoriasis combined with pregnancy admitted to our hospital in the past year are analyzed and reported as follows. Case 1, patient 29 years old, hospitalization number 566121, pregnancy and delivery 1. 5 years of common psoriasis, rash scattered all over the body, external use of borazine paste, boric acid solution and calomel solution, etc. Physiotherapy and Chinese herbal medicine were used several times. Occasionally, steroid ointment was used topically. The disease was stable for six months before pregnancy and was discontinued after pregnancy. In the fifth month of pregnancy, the disease worsened and the whole body rash expanded and a fresh rash appeared. She was treated with topical salicylic acid and mercuric chloride and took oral calcium tablets and folic acid without improvement. A 4300g male baby was delivered by cesarean section at 38 weeks of gestation due to large fetus with Apgar score of 10. Sixteen days after delivery, the rash on the whole body expanded significantly, with severe tingling and pruritus. The rash was treated with topical anthralin and low concentration retinoic acid, and the disease was controlled. Case 2, patient 37 years old, hospitalization number 588230, pregnancy and delivery 1. 10 years of common psoriasis, 7 years ago, due to irregular oral corticosteroids, she developed pustular psoriasis, which involved the whole body, and was treated with oral 8-methoxypsoralen and long-wave ultraviolet radiation. Since then, the disease has been treated with Chinese herbal medicine for recurrent attacks. During pregnancy, the psoriasis was stable and no special medication was given. A 3300g male baby was delivered by cesarean section at 41 weeks of gestation due to failed induction of labor. The neonatal score was 10 and the physical examination was unremarkable. She was not breastfed. Psoriasis recurred 10 days after delivery, with an enlarged and itchy rash. Topical benzine cream and psoriasis ointment were applied 3 months after delivery, and the disease was controlled by treatment with the immunosuppressant ragweed polysaccharide. Case 3, patient 34 years old, hospitalization number 600762, pregnancy and delivery 1. 13 years with psoriasis vulgaris, during which she was treated with topical Chinese medicine and salicylic acid, white mercury and other topical treatments. During the first year of pregnancy, she was treated with low concentration (0??1%) retinoic acid ointment topically. During pregnancy, the psoriasis completely resolved and the whole body rash disappeared. A 3250g baby girl was delivered vaginally at 39 weeks of gestation with an Apgar score of 10. 10 days after delivery, psoriasis recurred, initially with a rash on the head, which gradually extended to the extremities and trunk within 6 months. Treatment was resumed with Chinese and Western medicines. The psoriasis is usually divided into two types: the common type and the pustular type. The common type is clinically common; the pustular type is rare and more frequent than the common type. Therefore, psoriasis combined with pregnancy is more common in the common type. Clinical observation shows that most psoriasis patients have remission or disappearance during pregnancy, a few have stable disease and a few have worsening disease; breastfeeding after delivery has no significant effect on psoriasis; in addition, nearly 90% of psoriasis patients relapse or worsen within 4 months after delivery. The mechanism of the effect of pregnancy on psoriasis is not clear, but it has been suggested [ 1 ] that psoriasis is an autoimmune disease, and suppression of the body’s immune activity may alleviate its clinical symptoms. During pregnancy, in order to protect the fetus from maternal rejection, the immune activity of pregnant women is in a state of suppression. During the puerperium, the immune activity of the body increases, leading to clinical changes specific to the perinatal period of psoriasis. It is worth noting that herpetic pustulosis is a rare form of pustular psoriasis that develops during pregnancy, with no previous history of psoriasis or family history, and that it occurs suddenly in late pregnancy, often resolving within days to weeks after termination of pregnancy, and often recurs after another pregnancy[2] . There are no systematic studies on the prognosis of the fetus with psoriasis combined with pregnancy. The above three cases reported a good pregnancy outcome with no neonatal abnormalities, which may suggest that the combination of psoriasis vulgaris with pregnancy has no significant adverse effect on fetal and neonatal prognosis. However, some scholars believe that pustular psoriasis or herpes-like pustulosis during pregnancy can cause fetal distress in late pregnancy, and the more severe and prolonged the disease, the higher the incidence of placental hypoplasia, and in severe cases, fetal death or neonatal death can occur. In cases of herpes pustulosis in pregnancy, placental hypoplasia occurs in late pregnancy, usually with no abnormalities in B-ultrasound and fetal heart monitoring, followed by sudden loss of fetal movement and intrauterine fetal death. Therefore, in patients with herpes pustulosis combined with pregnancy, the fetus and placenta should be closely monitored during late pregnancy, and timely termination of pregnancy is beneficial for the regression of this type of psoriasis and the prognosis of the fetus. There are no statistical data on whether psoriasis affects the chance of conception and causes miscarriage in early pregnancy, but the incidence of conception and early miscarriage in treated women with psoriasis is not different from that of the normal population. Treatment and medication for psoriasis combined with pregnancy There is no specific cure for psoriasis. The conventional medication for psoriasis includes topical application of keratinizing agents such as anthralin, corticosteroids or low concentration retinoids; systemic therapy such as cortisone and methotrexate, and physiotherapy such as long wave ultraviolet irradiation (PUVA) and topical tar plus ultraviolet irradiation (PUVB). In addition, severe and intractable psoriasis is also treated orally with retinoids and cyclosporine. Retinoids are teratogens, and their use during pregnancy may cause multiple malformations in the neural tube, face and limbs of the fetus, and they have a long half-life in vivo, and their concentrations can still be measured in plasma 2-3 years after stopping. Animal studies have shown that the risk of miscarriage and malformation is significantly higher after treatment during pregnancy. Therefore, retinoids are contraindicated in the first two years of pregnancy and during the gestation period. Treatment [ 3] . In three cases admitted to our hospital, there were no contraindications to these treatments in the first trimester, and one patient had topical application of retinoic acid cream one year before pregnancy. In one case, topical treatment with retinoic acid cream was applied one year before pregnancy. No oral treatment was given during pregnancy, but only topical treatment with salicylic acid, white mercury and traditional Chinese medicine. In a foreign report[ 4] , a patient with persistent psoriasis combined with pregnancy was induced after oral methotrexate and hydroxyurea immunosuppressant treatment in the previous pregnancy. Cyclosporine is mostly used in organ transplant patients. It has been observed that the administration of cyclosporine during pregnancy in renal transplant patients does not affect the prognosis of pregnancy and does not increase the risk of fetus. However, animal studies suggest that administration of high doses of cyclosporine to pregnant rats may lead to fetal growth retardation and intrauterine death.5] According to Selim, oral cortisol hormone therapy is preferred for the safety of the mother and child in cases of pustular psoriasis deteriorating during pregnancy to ensure maternal safety. However, topical topical methotrexate combined with long-wave ultraviolet radiation is also an effective treatment for pustular psoriasis in late pregnancy, and the clinical application results suggest no significant adverse effects on fetal prognosis.