Platelets in Pregnancy

This is a prospective observational cohort study of platelet phenotype in pregnant patients at high-risk for the development preeclampsia. Blood samples will be collected prior to the initiation of daily aspirin and again in the second trimester to evaluate for platelet changes during pregnancy in patient's as a result of aspirin use and their association with adverse perinatal outcomes.

Inclusion Criteria (Case Group): * Pregnant patients receiving prenatal care prior to 17 weeks at NYU Langone Health- Obstetrics \& Gynecology Associates * Age 18-50 years * Singleton viable gestation * Pregnant patients at high risk of preeclampsia: Patients meeting USPSTF recommendation for low-dose aspirin (81 mg/day) prophylaxis for preeclampsia based on clinical risk factors (see below) Inclusion Criteria (Control Group): * Pregnant patients receiving prenatal care prior to 17 weeks at NYU Langone Health- Obstetrics \& Gynecology Associates * Age 18-50 years * Singleton viable gestation * Pregnant patients at low risk of preeclampsia: Patients who do not meet USPSTF recommendation for low-dose aspirin (81 mg/day) prophylaxis for preeclampsia based on clinical risk factors. Exclusion Criteria (Case and Control Group): * Allergy to aspirin * Antithrombotic or antiplatelet therapy * Anemia (hemoglobin \