Low Doses of Aspirin in the Prevention of Preeclampsia

Preeclampsia (PE) is a morbid and potentially lethal complication of pregnancy and is more common in women with specific risk factors. Aspirin (ASA) is currently the only prophylactic therapy for preeclampsia in high-risk women to be recognized by the US Preventive Task Force and should be initiated early in the second trimester of pregnancy, before 16 weeks of gestation. However, currently there is no literature comparing various low-dose ASA formulations in the risk reduction of PE. In the United States, the currently available low-dose ASA is over the counter and is found in 81mg tablets. Therefore, when clinicians initiate therapy with low dose ASA, they may prescribe 1 or 2 tablets of 81mg aspirin per day depending on personal preference and cannot be assisted by evidence to guide their decision.This study aims to determine the incidence of preterm PE or PE with severe features in women taking either 81mg or 162mg in a randomized setting, from a single center. The investigators hypothesize that the information gained from this trial will permit a more accurate sample size calculation for a larger clinical trial powered to accept or reject our testing hypothesis. If our hypothesis is rejected and 162mg of daily ASA is not associated with a lower incidence of severe or preterm PE compared to 81mg, this may be due to lack of power to detect a smaller effect. The investigators would then evaluate the feasibility and results and determine whether a larger trial is reasonable.