In the past, obstetric anesthesia refers to surgical anesthesia, but with the development of technology and the improvement of population quality, obstetric anesthesia is now more comprehensive, such as caesarean section, painless delivery, internal reversal, and painless abortion, etc. Obstetrical anesthesia is different from other surgical anesthesia, besides achieving the same requirements of pain relief and surgery as other surgical anesthesia, obstetrical anesthesia should achieve the safety of mother and child and the quality of surgery. Reducing surgical trauma and postoperative complications are the principles that obstetric anesthesia should focus on. Maternal blood flow has varying degrees of dilution, increased blood volume, increased cardiac output, and decreased resistance of the peripheral vascular system. It is believed that the fractional flow of uterine arteries and veins is high during pregnancy, and although the mother can gradually adapt to this physiological change, it is highly susceptible to disturbance and loss of equilibrium. Therefore, a high plane of spinal anesthesia cannot be tolerated. In order to maintain postural balance, the anterior curvature of the spine, especially in the lumbar region, can be reduced compensatorily. The drug injected into the spinal canal tends to flow in the direction of the thoracic curve, resulting in a high plane. Furthermore, the enlarged uterus and fetus affect the maternal breathing and circulation, especially when lying down, and can compress the vena cava in the case of muscle relaxation. This affects venous return and lowers blood pressure. Patients with gestational toxicity may have the following problems: 1, varying degrees of liver and kidney insufficiency 2, severe convulsions or coma 3, the fetus may be premature or stillborn 4, severe hypertension, which may lead to cerebrovascular accidents 5, the placenta may be early aborted To create favorable conditions for surgery, the following measures can be done before surgery: 1, inhalation of high concentrations of oxygen 2, hibernation drugs to properly control blood pressure 3, 10% magnesium sulfate 10- 20 ml static point, to prevent convulsions, in favor of the uterine blood supply. Severe cases can be used thiopental sodium plus muscle relaxants to control respiration 4, also can be used to reduce blood pressure epidural anesthesia, if necessary, can increase the amount of local anesthetics, auxiliary analgesic, sedative drugs. In cases of hyperemesis, eclampsia and twin fetuses, the placental blood supply may be reduced by about 15% compared to normal, the placental villi microvessels are spiral, the effect of vasodilators is small, while the effect of vasoconstrictors is large, improper application, more reduce the placental blood supply and its arterial partial pressure of oxygen, the placental partial pressure of oxygen is normally at 75-100%, should not be lower than 50%. Intraoperative prevention of elevated blood pressure and treatment: In addition to intraoperative infusion should not be too fast, do not use blood pressure-raising drugs as prophylactic medication in anesthesia. If the intraoperative blood pressure drops 20% for a short period of time, the problem is not serious, and no or less antihypertensive drugs should be used as much as possible, and oxygen can be administered first while changing the position and accelerating the fluid input to improve it. If the blood pressure continues to fall by more than 30%, a small amount of ephedrine can be used, but avoid applying it at the same time as oxytocin, otherwise the blood pressure may increase dramatically and cause cerebrovascular accidents. The use of antihypertensive drugs can not only promote the occurrence of hypertension after delivery, but also make the uterine artery contraction affect the blood flow, resulting in fetal asphyxia, and should be avoided. In case of intraoperative hypertension, ephedrine is preferred, followed by mephedrone, and methoxamine can affect the blood flow in the uterine artery and lead to fetal asphyxia, and should be prohibited. (Chlorpromazine is mainly decomposed in the liver and eliminated from the body with the stool, and does not pass the placental barrier.) If the blood pressure still cannot be reduced to a satisfactory level, it should be observed for 25 minutes before renewal. If necessary, pethidine and promethazine combination (both analgesic, sedative and anti-allergic effects) can be used.