• Provision of signed and dated informed consent form.

• Stated willingness to comply with all study procedures and availability for the duration of the study.

• Ability to take oral medication and be willing to adhere to the prescribed aspirin regimen.

• Patients with a gestation less than or equal to 6 weeks, 6 days (as determined by patient record of LMP or ART date).

• Patients between 18-45-year old who have one or more risk factors for preeclampsia and/or pregnancy loss, including:

‣ preeclampsia in a previous pregnancy,

⁃ gestational diabetes in a previous pregnancy,

⁃ any documentation of fetal growth restriction or low birth weight in a prior pregnancy,

⁃ preterm birth in a previous pregnancy,

⁃ known multifetal gestation at enrollment,

⁃ chronic hypertension,

⁃ pregestational diabetes,

⁃ kidney disease,

⁃ systemic lupus erythematosus,

‣ nulliparity,

‣ pre-pregnancy body mass index \>30,

‣ family history of preeclampsia (i.e., mother or sister),

‣ Black persons (due to social, not biological reasons),

‣ Maternal age 35 years or older,

‣ lower income (will be determined by qualification of public health insurance),

‣ conceived with fertility treatment (including in vitro fertilization, ovulation induction, or intrauterine insemination),

‣ history of one or more prior pregnancy losses \<20 weeks gestation,

‣ history of stillbirth in a prior pregnancy,

‣ An interval of greater than 10 years since the last pregnancy.