APPLE: Aspirin to Prevent Pregnancy Loss and Preeclampsia

Inclusion Criteria 1. Provision of signed and dated informed consent form. 2. Stated willingness to comply with all study procedures and availability for the duration of the study. 3. Ability to take oral medication and be willing to adhere to the prescribed aspirin regimen. 4. Patients with a gestation less than or equal to 6 weeks, 6 days (as determined by patient record of LMP or ART date). 5. Patients between 18-45-year old who have one or more risk factors for preeclampsia and/or pregnancy loss, including: 1. preeclampsia in a previous pregnancy, 2. gestational diabetes in a previous pregnancy, 3. any documentation of fetal growth restriction or low birth weight in a prior pregnancy, 4. preterm birth in a previous pregnancy, 5. known multifetal gestation at enrollment, 6. chronic hypertension, 7. pregestational diabetes, 8. kidney disease, 9. systemic lupus erythematosus, 10. nulliparity, 11. pre-pregnancy body mass index \>30, 12. family history of preeclampsia (i.e., mother or sister), 13. Black persons (due to social, not biological reasons), 14. Maternal age 35 years or older, 15. lower income (will be determined by qualification of public health insurance), 16. conceived with fertility treatment (including in vitro fertilization, ovulation induction, or intrauterine insemination), 17. history of one or more prior pregnancy losses \<20 weeks gestation, 18. history of stillbirth in a prior pregnancy, 19. An interval of greater than 10 years since the last pregnancy. Exclusion Criteria 1. Known allergies to aspirin. Exclusion to allergies to other non-steroidal anti-inflammatory agents (NSAID) will be determined on a case-by-case basis; 2. Clinical indication for anticoagulant therapy, including prior or current thrombosis, antiphospholipid syndrome, or known major thrombophilia; 3. Clinical indication for chronic use of NSAIDS during pregnancy; 4. Medical contraindication to aspirin therapy, including untreated uncontrolled asthma, untreated symptomatic nasal polyps, bleeding disorders, or history of gastrointestinal ulcer. 5. Patients with pelvic pain or bleeding who require urgent care (i.e., active vaginal bleeding greater than or equal to expected menses, open cervical os suggesting active miscarriage or severe pain requiring evaluation for ectopic pregnancy)