Predictors of Aspirin Failure in Preeclampsia Prevention

Inclusion Criteria: 1. Women aged 18-45 years with prior history of preeclampsia who received low dose aspirin in their subsequent gestation and either did or did not have a recurrence of preeclampsia. 2. Aspirin was given in their subsequent pregnancy in a 81 mg dose prior to 16 weeks of gestation, and was taken with a self-reported compliance rate of at least 80% 3. Subsequent pregnancy lasted beyond 20 weeks of gestation 4. Willingness to abstain from non-prescription non-steroidal anti-inflammatory drugs (NSAIDs), which are known to interfere with platelet function assays, for one week prior to platelet function analyses. 5. Healthy controls recruited for SNP assay optimization: Women aged 18 years or older, with no other specific inclusion criteria that need to be met in order to be enrolled for the study. Exclusion Criteria: 1. Age \<18 years or \>45 years 2. Any clinically significant adverse reaction to aspirin on prior exposure 3. Known bleeding disorder based on personal or family history 4. History of kidney or liver impairment 5. Current pregnancy 6. Current use of antithrombotic agents (e.g., aspirin, clopidogrel, warfarin, direct acting oral anticoagulants). 7. Chronic hypertension (systolic blood pressure \>140 mmHG or diastolic pressure \>90 mmHG, or use of antihypertensive drugs or diagnosis made by clinician) 8. Diabetes mellitus 9. Current known malignancy 10. History of hemorrhagic stroke 11. Participants may be excluded at the discretion of the investigator for medical, psychological or other reasons 12. Rockefeller students, and Rockefeller employees in the Coller lab, are excluded from participation. 13. Healthy controls: A. \<18 years of age. B. Participants may be excluded at the discretion of the investigator for medical, psychological or other reasons C. Rockefeller students, and Rockefeller employees in the Coller lab, are excluded from participation.