It can cause gestational hypertension, excessive amniotic fluid, postpartum hemorrhage, preterm delivery, macrosomia and stillbirth. Gestational diabetes mellitus is a common comorbidity during pregnancy, referring to abnormal glucose metabolism or potential hypoglycemia during pregnancy, diabetes mellitus that appears or is discovered only during pregnancy, the incidence rate in China is 1%-5%, and there is a significant trend of increase in recent years [1]. Risk factors for the occurrence of gestational diabetes mellitus Current studies have shown that age, race, obesity, family history of diabetes mellitus and poor reproductive history are the main factors affecting the development of gestational diabetes mellitus [2]. 1, Advanced gestational age is now recognized as a major risk factor for gestational diabetes. The risk of gestational diabetes mellitus in pregnant women aged 40 years and above is eight times higher than that in pregnant women aged 20 to 30 years. In addition to the maternal age factor in addition to affecting the occurrence of diabetes, the older the age of the pregnant woman diagnosed gestational diabetes mellitus, the smaller the gestational week. 2, race: and adult type 2 diabetes and race similar to the relationship, gestational diabetes has obvious geographical and racial correlation. Our country has a higher incidence of gestational diabetes than compared with the European race. Racial factors in addition to the genetic factors caused by, can not except economic and cultural, dietary habits and other factors in the role. 3, obesity: is the occurrence of impaired glucose tolerance and diabetes mellitus important risk factors. Currently, BMI is commonly used as an indicator of obesity, and the risk of gestational diabetes mellitus in pregnant women with a BMI ≥ 20.9 is twice as high as in those with a BMI ≤ 19.1. 4, family history of diabetes mellitus and poor obstetric history: family history of diabetes mellitus is a risk factor for gestational diabetes mellitus, the risk of gestational diabetes mellitus in people with a family history of diabetes mellitus is 1.55 times the risk of people without a family history of diabetes mellitus, and first-degree relatives who have a family history of diabetes mellitus is elevated to 2.89 times. Adverse effects of gestational diabetes mellitus on mother and child GDM can cause adverse pregnancy outcomes such as gestational hypertension, excess amniotic fluid, postpartum hemorrhage, preterm delivery, macrosomia and stillbirth, while the extent of its effects depends on the diabetic condition and glycemic control [3]. Risks to pregnant women 1.Increased rate of spontaneous abortion, especially in early pregnancy with high blood glucose. 2, hypertensive disorders in pregnancy: diabetic pregnant women are prone to hypertension, pre-eclampsia, etc., especially common in the long course of diabetes mellitus combined with microvascular lesions, or diabetes mellitus combined with nephropathy. 3, preterm labor: gestational diabetes mellitus pregnant women occur premature birth is significantly higher than normal pregnant women, amniotic fluid is one of the reasons, at the same time, the proportion of preterm birth of medical origin is also more. 4, infection: diabetes combined with pregnancy of pregnant women with decreased resistance, easy to have the risk of infection, especially asymptomatic bacteriuria and pyelonephritis and other urinary tract infections. 5, excessive amniotic fluid: the proportion of pregnant women with unsatisfactory blood glucose control with excessive amniotic fluid is as high as 17%, which is mainly related to fetal malformation, increased placental area, osmotic diuresis caused by fetal hyperglycemia, as well as macrosomia and other factors. 6.Various complications during labor: including prolonged labor, weak contractions, postpartum hemorrhage and so on. Risks to the fetus (newborn) While the pregnant woman’s blood sugar rises, the excess sugar can easily reach the fetus through the placenta, causing the fetus to develop hyperglycemia. Once the blood sugar of the fetus rises, its pancreas will secrete more insulin to metabolize the excess glucose. The excess glucose and insulin in the fetus’s blood will cause it to produce more fat, protein, and gain weight and become a giant baby. Gestational diabetes mellitus has the following effects on the fetus: 1, can make the fetal mortality rate increase: research that the fetal mortality rate increase is mainly related to the pregnant woman’s elevated blood glucose levels. Gestational diabetes patients can reduce the fetal mortality rate if they can strictly control their blood sugar and strengthen the monitoring of the fetus in the late stage of pregnancy. 2, can form a huge fetus: gestational diabetes mellitus occurs in the middle and late stages of pregnancy, when the fetal organs have been formed, so the main effect on the fetus is to lead to its excessive development, thus forming a huge fetus. 3, can lead to fetal malformation: gestational diabetes mellitus patients conceived by the fetus is prone to neurological and cardiovascular malformations, such as spina bifida, hydrocephalus, congenital anal atresia and so on. 4, can lead to neonatal jaundice: pregnant women with diabetes, can lead to fetal hypoxia in the womb, and make the fetal body erythropoietin increase, causing erythrocytosis. Newborns with erythrocytosis are prone to neonatal jaundice because a large number of red blood cells in their bodies are destroyed. 5, can lead to neonatal respiratory distress syndrome: gestational diabetes mellitus patients born of infants suffering from neonatal respiratory distress syndrome is non-diabetic pregnant women born of infants six times the odds. The occurrence of this syndrome and gestational diabetes patients failed to control blood sugar well leading to fetal hyperglycemia has a close relationship. 6, can lead to neonatal hypoglycemia: gestational diabetes mellitus patients conceived by the fetus is prone to the formation of hyperinsulinemia, the disease can make the newborn hypoglycemia. For the mother and child long-term effects Gestational diabetes mellitus on the long-term effects of pregnant women are: about 50% -70% of pregnant women transformed into type 2 diabetes, gestational diabetes mellitus of pregnant women in another pregnancy the risk of gestational diabetes mellitus is about 60%. The long-term effects on the newborn include the tendency of pediatric obesity and diabetes, and neuropsychiatric developmental problems. Therefore, early glycemic control is beneficial to maternal and infant outcomes. Pregnant women with risk factors should be screened as early as possible, and dietary guidance, weight management, and exercise during pregnancy should be used to maintain stable glycemic control throughout pregnancy to minimize the occurrence of maternal and infant complications.