1. Health education and guidance: (1) Awareness and prevention of preterm labor. (2) Nutrition and lifestyle guidance. (3) The significance of fetal systematic ultrasound screening. (2) Routine health care: (1) Inquire about fetal movement, vaginal bleeding, diet and exercise. (2) Physical examination is the same as 14 to 19 weeks of pregnancy +6 prenatal examination. 3.Required items: (1)Fetal systematic ultrasound screening (18～24 weeks of gestation) to screen for serious malformations of the fetus. (2) Blood routine and urine routine. (4) Preparatory examination: cervical evaluation (ultrasound measurement of cervical length). Antenatal examination at 24 to 28 weeks of pregnancy 1. Health education and guidance: (1) Recognition and prevention of preterm labor. (2) Significance of screening for gestational diabetes mellitus (GDM). (2) Routine health care: (1) Ask about fetal movement, vaginal bleeding, contractions, diet and exercise. (2) Physical examination is the same as 14 to 19 weeks of pregnancy +6 prenatal examination. (3) Required items: (1) GDM screening. First, 50g glucose screening (GCT), if the blood glucose is 7.2-11.1mmol/L, then 75g OGTT; if >11.1mmol/L, then fasting blood glucose will be measured. The international recently recommended method is not necessary to first 50g GCT, if possible, can directly perform 75g OGTT, the upper limit of normal for fasting blood glucose 5.1mmol / L, 1h postprandial blood glucose 10.0mmol / L, 2h postprandial blood glucose 8.5mmol / L; or through the detection of fasting blood glucose as a screening criterion. (2) Urine routine. 4. Preparatory items: (1) Anti-D titer test (Rh negative). (2) Cervicovaginal secretion test for fetal fibronectin (fFN) level (for those at high risk of preterm labor). Antenatal examination at 30 to 32 weeks of pregnancy 1. Health education and guidance: (1) Guidance on the mode of delivery. (2) Begin to pay attention to fetal movement. (3) Breastfeeding instruction. (4) Instruction on newborn care. (2) Routine health care: (1) Ask about fetal movement, vaginal bleeding, contractions, diet and exercise. (2) Physical examination is the same as 14 to 19 weeks of pregnancy +6 prenatal examination; fetal position examination. 3. Required items: (1) Blood and urine routine. (2) Ultrasonography: fetal growth and development, amniotic fluid volume, fetal position, placenta position. (4) Preparatory items: for those at high risk of preterm labor, ultrasound measurement of cervical length or cervicovaginal secretion to detect fFN level. Antenatal examination at 33 to 36 weeks of pregnancy 1. Health education and guidance: (1) Guidance on lifestyle before delivery. (2) Knowledge related to labor and delivery (symptoms of approaching labor, guidance on delivery methods, labor analgesia). (3) Screening for newborn diseases. (4) Prevention of depression. (2) Routine health care: (1) Inquire about fetal movement, vaginal bleeding, contractions, skin itching, diet, exercise, and preparation for labor. (2) Physical examination is the same as prenatal examination at 30 to 32 weeks of pregnancy. (3) Required items: urine routine. (1) Screening for Group B Streptococcus (GBS) at 35～37 weeks of pregnancy: pregnant women with high-risk factors (e.g. diabetes mellitus, newborns born from previous pregnancy with GBS infection, etc.), take perianal and lower 1/3 of vaginal secretions for culture. (2) Liver function and serum bile acid test at 32 to 34 weeks of gestation [pregnant women in areas with high prevalence of intrahepatic cholestasis during pregnancy (ICP)]. (3) Electronic fetal heart monitoring [no load test, (NST)] test starting at 34 weeks of gestation (pregnant women at high risk). (4) ECG review (high-risk pregnant women).