There are 4 sources and 3 consumption modes of amniotic fluid in uterus. It is very important to maintain a constant amount of amniotic fluid

Baby in the womb, the placenta provides it with oxygen and nutrients, coupled with the protection of the amniotic cavity, can be said to live in a very safe and ideal environment. Among them, the function of amniotic fluid is also indispensable. < p > < p > appropriate amount of amniotic fluid has buffering effect on fetus, which can avoid fetal extrusion, prevent fetal limb adhesion, and avoid fetal distress caused by direct compression of uterine muscle wall or fetus on umbilical cord. It can also keep a constant temperature in the amniotic cavity. Compared with maternal plasma, amniotic fluid is a hypotonic fluid. Amniotic fluid can be transferred to fetal placental vessels through the amniotic chorionic interface, but only a small amount of amniotic fluid is transferred to maternal plasma. < p > < p > amniotic fluid is continuously exchanged in the amniotic cavity, which is supplemented by various sources while absorbed to maintain a relatively constant amount of amniotic fluid. Only the liquid exchange between the mother and the fetus through the placenta can reach about 3600ml per hour. < p > < p > the amount of amniotic fluid increased gradually until 38 weeks of gestation, which was about 1000 ml; after that, the amount of amniotic fluid began to decrease gradually, and at 40 weeks of pregnancy, the amount of amniotic fluid was only about 800 ml. There are a lot of hormones and enzymes in amniotic fluid. In the early stage of pregnancy, amniotic fluid is colorless and transparent; at term, amniotic fluid is slightly turbid and no longer transparent, with pH value of about 7.20, because at this time, amniotic fluid contains fetal fat, fetal exfoliated epithelial cells, hair, a small amount of white blood cells, albumin and other small flakes, but the water content is still as high as 98% ~ 99%. < / P > < p > the so-called polyhydramnios refers to pregnant women whose amniotic fluid volume exceeds 2000ml at any time during pregnancy. The probability of polyhydramnios is about 0.5% ~ 1%. < / P > < p > the direct cause of excessive amniotic fluid is that the amount of amniotic fluid produced is greater than the amount of absorption, mainly including increased urine volume, increased exudate, dysphagia of amniotic fluid. Fetal diseases, such as fetal structural abnormalities, chromosomal or genetic abnormalities, metabolic diseases, fetal tumors, neuromuscular dysplasia, placental and umbilical cord lesions, are one of the fundamental causes of hydramnios. Gestational diabetes mellitus, Rh blood group incompatibility between mother and infant, fetal immune edema, placental villus edema, etc., may lead to excessive amniotic fluid. Under the condition of polyhydramnios, fetal position abnormality, fetal distress, premature rupture of membranes, placental abruption and so on are prone to occur, and the rate of premature birth is also increased. If the amniotic fluid flows out too fast, it may lead to the prolapse of umbilical cord. < / P > < p > in the case of excessive amniotic fluid, it will lead to increased uterine tension of pregnant women, affect the rest of pregnant women, resulting in increased blood pressure, may also lead to postpartum uterine atony, increase the risk of postpartum hemorrhage. < p > < p > oligohydramnios is mainly related to the decrease of amniotic fluid production or the increase of amniotic fluid leakage. If the rate of amniotic fluid leakage exceeds the rate of amniotic fluid formation, oligohydramnios may be caused. The abnormal fetal structure is one of the fundamental causes of oligohydramnios, which is mainly caused by urinary system structural abnormalities and oligohydramnios caused by oliguria or anuria. Placental dysfunction, such as prolonged pregnancy over 42 weeks and placental degeneration, is also the root cause of oligohydramnios. Inflammation, intrauterine infection, pregnancy induced hypertension, dehydration of pregnant women, insufficient blood volume, or taking certain drugs may lead to oligohydramnios. Oligohydramnios is often accompanied by fetal growth restriction. Oligohydramnios occurs in the early pregnancy, most of which are caused by fetal structural abnormalities; oligohydramnios occurs in the middle and late stages of pregnancy, leading to the direct effect of external pressure on the fetus, which can cause fetal malformation and hypoxia. < p > < p > Star House parenting notes: pregnant mothers should pay attention to their own abdominal size during pregnancy. If they are significantly larger or smaller than other pregnant mothers and accompanied with discomfort, they need to pay attention to it. The relevant prenatal examination items should also be carried out on time, including fetal heart rate monitoring, B-ultrasound measurement of amniotic fluid volume, various examinations to exclude fetal structural abnormalities and deformities, glucose tolerance, blood pressure measurement, and uterus Height, abdominal circumference and other examinations should not be careless. Cai Shaofen stopped pregnancy for the first time. The 4 indexes on the B-ultrasound sheet in the early pregnancy were used to see whether the fetal development was good or not