This study will explore the effectiveness of low-dose aspirin on preventing pre-eclampsia in high-risks pregnant women by comparing the incidence of pre-eclampsia and pregnancy outcomes.

Currently，low-dose aspirin is a commonly used drug to prevent pre-eclampsia. Many guidelines recommend starting low-dose aspirin in early pregnancy in high-risks pregnant women. However, the applicable population and use method of aspirin are still controversial in clinical practice. This study will explore the effectiveness and use method of low-dose aspirin by comparing the incidence of pre-eclampsia and pregnancy outcomes.

Inclusion Criteria:

• Age between 18-55 years

• Gestational age between 12-20 weeks of pregnancy

• High risk of developing pre-eclampsia

  • At least one of the following risk factors: Pre-eclampsia in a previous pregnancy , Multiple pregnancy，Diabetes Mellitus(Type 1 or 2), Chronic Hypertension，Renal disease, Autoimmune disease.
  • At least two of the following risk factors: Primiparity，Pre-pregnancy Body Mass Index ≥28kg/m2, Age ≥35 years, Family members have a history of pre-eclampsia.

• Maternal informed conset obtained

Exclusion Criteria:

• Contraindication to aspirin therapy (including but not limited to allergy and high bleeding risk)
• Patient with known intention to terminate pregnancy
• Fetal abnormalities detected （including but not limited to major fetal malformation and FGR）
• Severe heart, liver, renal disease who can not burden the experiment
• Alcohol and drug abuse
• Being in another drug experiment within 3 months