1.Improve prenatal health care from the “head” 1.Avoid obvious toxic exposure (such as tobacco, drugs, etc.) before or early in pregnancy. 2, should pay attention to the rational use of drugs, especially prescription drugs and some nutritional supplements (folic acid, DHA) use. 3, to ensure the smoothness of some diseases before pregnancy, for example, diabetic patients should control blood sugar smoothly; chronic hypertensive patients should keep blood pressure smooth; patients with convulsions should use safer anticonvulsants; patients with connective tissue disease should be controlled in the resting phase; heart disease should be clearly graded according to the clinical manifestations of patients, etc. The importance of ultrasound for screening and diagnosis in pregnancy Ultrasound examination in early pregnancy can clarify the gestational weeks and whether it is a multiple pregnancy. The type of placenta, uterine artery resistance and large organ defects can be clarified at 11~13+6 weeks of gestation. In addition, NT examination helps to improve the detection rate of trisomy 21. Ultrasound in early pregnancy can detect the type of multifetal pregnancy and chorionicity. If it is a double amniotic double chorionic twin, normal labor and delivery until 36~37 weeks. If single chorionic twin fetus is found, about 1/3 to 1/4 may develop into twin fetal transfusion syndrome (TTTS), selective fetal growth restriction (sIUGR) and/or twin fetus a reverse arterial perfusion syndrome (TAPS) and increased incidence of major structural malformations, which requires examination of development, amniotic fluid volume, umbilical blood flow, middle cerebral artery PI and peak flow velocity index every 2 weeks ( PVIV), and if normal, delivery at 35-36 weeks. Early pregnancy ultrasound suggestive of abnormal uterine artery resistance indicates maternal maladaptive or delayed pregnancy, increased risk of poor placental formation, and increased risk of early onset preeclampsia, and oral aspirin 100 mg/d prophylaxis can be started before 14 weeks. Midtrimester ultrasound suggestive of shortened cervical canal (less than 25 mm) suggests a 35% incidence of spontaneous preterm birth (sPTB), while the risk of spontaneous preterm birth is less than 1% if the cervical length is >30 mm. Treatment of patients with shortened cervical canal suggested by ultrasound (90-100 mg of micronized progesterone placed vaginally each night) reduces the incidence of spontaneous preterm delivery by 40%. Increased uterine artery resistance occurs in approximately 30% of cases on mid-pregnancy ultrasound and will be normal in most cases when repeated at 24 to 26 weeks, indicating delayed placental formation. Persistent increased resistance is indicative of an increased risk of maternal hypertensive disease. If ultrasound indicates abnormal resistance of umbilical artery blood flow, it indicates an increased risk of fetal growth restriction and needs to be differentiated from abnormal placenta formation, thrombosis, fetal infection, etc. Repeat ultrasound examination is needed within 4 weeks. The incidence of spontaneous preterm delivery at less than 32 weeks is 1%-2%, and the most inexpensive drug with minimal side effects is recommended to preserve the fetus for 48h and complete the prophylactic fetal lung treatment. The regimen is the application of glucocorticoids: betamethasone 12 mg intramuscularly 1/day x 2d or dexamethasone 6 mg intramuscularly 1/12h x 2d. Antibiotics do not prolong the gestational week, but ampicillin (500 mg orally every 6 h for 2d) reduces the incidence of preterm B hemolytic streptococci. Uterine contraction inhibitors can be used at <34 weeks of gestation with regular contractions. Nifedipine, indomethacin, and ampicillin are all first-line agents for suppressing contractions with similar effects, but all have some adverse effects. Nifedipine (40mg loading dose orally, followed by 20mg every 4-6h) can cause a drop in blood pressure. Indomethacin (50 mg loading dose orally, followed by 25 mg every 4-6 h) may reduce fetal urination and may cause ductal atresia when used before 3 4 weeks. Ampoule makes heart rate faster and raises blood sugar, etc. Magnesium sulfate (6g loading dose, 2g/ h) protects fetal brain from oxygen free radicals. If preterm labor is suppressed, no increase in dosing is needed, and outcomes improve significantly with increasing gestational weeks of labor. Premature rupture of membranes at less than 34 weeks accounts for 25%-40% of spontaneous preterm births, and the earlier the onset of premature rupture of membranes at term (PPROM), the longer the incubation period. Therapeutic application of antibiotics can prolong the incubation period (erythromycin 500mg orally every 6h for 7d) and also reduce the incidence of premature group B hemolytic streptococci. Magnesium sulfate (6g loading dose, 2g/h) can protect the fetal brain from oxygen free radicals. If the patient has no abnormal symptoms, delivery is at 34 weeks of gestation (if amniotic fluid testing indicates fetal lung maturation, delivery is at 32 weeks). High-risk and low-risk pregnancies can be distinguished by some common screening tools, and the main effort should be devoted to high-risk groups; the physician who performs prenatal screening should have good skills in ultrasound detection, otherwise it is like the chief surgeon losing his scalpel. There is a need for pragmatic and effective prenatal care to reduce medical costs for families and society.