Rct Assessing Pregnancy - Piroxicam for Ec With Levonorgestrel

Inclusion Criteria: * Between 16-35 years old and desire LNG for EC * Unprotected intercourse within 72 hours * Biologically capable of pregnancy * Regular menstrual cycle 21-35 days long with known LMP +/- 3 days * Working cell phone number that receives text messages (for Aim 3 participants phone with capability to download and use the Oova application and submit data) * Fluent in English and/or Spanish * Willing to comply with the study requirements including 1-month urine pregnancy test * No known contraindications to oral LNG or piroxicam - For secondary outcome assessing pregnancy risk for participants receiving study drug on day of ovulation or later - are currently using a menstrual cycle tracking application and can demonstrate according to the application that they are on the day of ovulation or post ovulation. Exclusion Criteria: * Current pregnancy (+urine pregnancy test in clinic) * Breastfeeding, post abortion or postpartum without resuming menstruation * Use of hormonal contraception (including oral EC) within seven days of enrollment * Use of NSAIDs (ibuprofen, naproxen, celecoxib, diclofenac, aspirin) in the prior week * Highly effective contraception including permanent contraception (including partner with vasectomy), IUD, or contraceptive implant * Allergy to LNG or piroxicam * Desires UPA for EC History of stroke, myocardia infarction, ischemic heart disease, uncontrolled hypertension, congestive heart failure, peptic ulcer disease, renal or hepatic failure. Currently taking anticoagulants, corticosteroids, cyclosporine, lithium, methotrexate, or tacrolimus.