Detailed Description:
The investigators will conduct a randomized control trial to estimate the efficacy of low dose aspirin in preventing preeclampsia in Chinese pregnant women who are evaluated with risk factors. The investigators will also obtain biological specimen including maternal blood, cord blood, placenta specimen and etc. for basic science studies.
Rationale for Design:There is a lack of evidences or guideline of aspirin using in preventing PE for Chinese women. The investigators will conduct a randomized control trial, which is the 'gold standard' of research design, hoping to answer the question.
