The Influence of a Single Dose of Emergency Contraception on Markers of Venous Thrombosis and Vascular Function in Young, Healthy Females.
The goal of this double-blind randomized controlled trial is to learn about the impacts of a single dose of Plan B® on the cardiovascular system in young, health, premenopausal females. The main questions it aims to answer are: 1. What is the short-term affect of Plan B® affect on the venous system? 2. What is the short-term affect of Plan B® affect on the health of arteries? Researchers will compare a single dose of Plan B® (1.5 mg of levonorgestrel) to a placebo to see if Plan B® has unique effects on the cardiovascular system. Participants will: 1. Undergo baseline measurements of venous thrombosis markers, blood pressure, and measures of arterial function using ultrasound. 2. Be randomized to either take a Plan B® or placebo pill 3. Repeat baseline measurements of venous thrombosis markers, blood pressure, and measures of arterial function using ultrasound each hour, for 6-hours, and then 24- and 48- hours after taking the Plan B® or placebo pill.
• Provide written informed consent.
• Pre-menopausal female.
• 18 - 35 years of age.
• Naturally cycling (i.e., not using any form of hormonal contraception for ≥ 3 months).
• Eumenorrheic (i.e., experiencing a predictable menstrual cycle lasting 21-45 days).
• In the surrounding Hamilton area, or able to visit McMaster for study visits.
• Not pregnant.