Aspirin to Prevent Preeclampsia in Women With Elevated Blood Pressure and Stage 1 Hypertension (ASPPIRE)

At the baseline visit, women will go through informed consent and review of study eligibility. Objectives of the study, participation requirements, eligibility inclusion and exclusion will be reviewed in detail. If these are not met, the woman is excluded from the study. If she meets inclusion criteria, a checklist of exclusion criteria will be reviewed. If any exclusions are met, the woman is excluded from the study. The consent form will be reviewed in detail. If the woman consents and signs all pages of the form, randomization follows. Randomization will be done in a 1:1 allocation ratio between the treatment and placebo arms, stratified by blood pressure group (elevated blood pressure and stage 1 hypertension). A computer algorithm will assign participant based on random permuted blocks design with block size between 2-4 within each strata. Each participant will have an assigned Study ID number that is linked to their random assignment. Participants will be contacted by telephone 1 week after randomization. The purpose of this visit is to ensure the participant has received study medication and initiated the regimen. The third encounter will be 6 weeks (+/- 1week) after randomization in person to coincide with routine prenatal visit or via telephone. The purpose of this study visit is to review their pregnancy course, use of study medications, any side effects, difficulties with the study, and have opportunities to make comments and/or ask questions. The participants will be asked to bring their study medication for pill count at the time of this encounter, if the study visit is able to be performed in person. Study participants will continue their routine prenatal care with pregnancy management performed routinely per their provider. The fourth encounter will be 16 weeks (+/- 1week) after randomization in person to coincide with routine prenatal visit or via telephone. If the participant is already delivered by this time, the visit will be performed via telephone postpartum. The purpose of this study visit is to review their pregnancy course, use of study medications, any side effects, difficulties with the study, and have opportunities to make comments and/or ask questions. The participants will be asked to bring their study medication for pill count at the time of this encounter, if the study visit is able to be performed in person. The rest of the study will be conducted via chart review. Each prenatal visit will be reviewed for blood pressure, evaluation of symptoms, review of any laboratory and/or imaging results. New diagnoses, medications, and hospital admissions will be documented. Delivery records will be abstracted for outcomes listed below. Neonatal records will be reviewed from birth until 1 year of age. Neonatal and infant chart abstraction will include birthweight, Apgar scores, hospital course, problem visit, diagnoses, medications, emergency department visits, and hospitalizations. Participant's postpartum course will be reviewed for 1 year postpartum, including outpatient visits, emergency department visits, and any hospitalizations. The study will be performed by an intent-to-treat analysis. Thus, even women who discontinue study medication will be included in final analyses.