According to the American College of Obstetricians and Gynecologists (ACOG), pregnancy-induced hypertension is defined as a new onset of systolic and/or diastolic blood pressure ≥140/90 mmHg after 20 weeks of gestation, with at least 4 hours between two blood pressure measurements, and blood pressure can return to normal after childbirth. Preeclampsia is defined as the presence of proteinuria or multi-organ dysfunction on the basis of pregnancy-induced hypertension. Obese women are a high-risk group for preeclampsia, and the preventive use of low-dose aspirin (LDA) is one of the currently recognized effective interventions. Obesity, as an independent risk factor for preeclampsia, can increase the risk of the disease by 2 to 3 times. With the rising global obesity rate, the prevention and control of preeclampsia in obese pregnant women has become an important challenge in the field of perinatal medicine. The WHO report indicates that the incidence of preeclampsia in obese women is significantly higher, with a 20-30% increase in preeclampsia risk for every 5-unit increase in BMI. The incidence of preeclampsia in obese women can reach 15-25%. At present, the clinical application of oral aspirin for the prevention of preeclampsia in China mainly follows authoritative consensuses such as the "Guidelines for the Diagnosis and Treatment of Hypertensive Disorders in Pregnancy (2020)", which recommends that high-risk pregnant women (such as those with obesity, chronic hypertension, and a history of preeclampsia in the previous pregnancy) take low-dose aspirin (50-150 mg/d) orally from 12 to 16 weeks of gestation for prevention. However, in actual clinical practice, a dose of 100 mg/d is commonly used, and there is still a lack of clear guidance on whether the dose needs to be adjusted for obese pregnant women. At present, the dose of aspirin mainly used in China is still 100 mg, while foreign studies are more inclined to use 150 mg. Therefore, this study is designed to conduct a randomized controlled trial to compare the efficacy and safety of 100 mg and 150 mg aspirin in preventing preeclampsia in obese pregnant women, to optimize the LDA strategy for the prevention of preeclampsia and provide high-quality evidence for clinical practice.

This study aims to compare the efficacy and safety of 100 mg and 150 mg aspirin in preventing preeclampsia in obese pregnant women and to optimize the LDA strategy for the prevention of preeclampsia. Obese pregnant women at high risk of preeclampsia will be randomly assigned in a 1:1 ratio at 12-16 weeks of gestation. The control group will take 100 mg of aspirin orally every night, while the experimental group will take 150 mg of aspirin orally every night, until 36+0 to 36+6 weeks of gestation. The incidence of preeclampsia will be compared between the two groups.

Inclusion Criteria:

1. Age 18-45 years;
2. Pregnancy 12-16 weeks, NT normal;
3. Singleton pregnancy;
4. a.BMI ≥35kg/m²; b. 28≤BMI <35 kg/m², and at least one risk factor: history of preeclampsia, chronic hypertension, type 1 or type 2 diabetes, autoimmune disease (excluding antiphospholipid syndrome), nulliparous, family history of preeclampsia, placental abruption, stillbirth, SGA, more than 10 years between pregnancies, in vitro fertilization-embryo transfer;
5. Sign informed consent

Exclusion Criteria:

• 1. Aspirin allergy or contraindication (such as active gastric ulcer, coagulation disorder); 2. Multiple pregnancies; 3. Other severe comorbidities that may lead to pregnancy complications; 4. Seizures; 5. Renal disease, baseline proteinuria (proteinuria> 3+, or protein-to-creatinine ratio ≥ 0.3); 6. Patients taking aspirin for other reasons (such as stroke, heart disease)