Effects of Obesity on Pharmacokinetics of the Levonorgestrel Emergency Contraceptive Pill

Inclusion criteria

• Women between ages 18-35 years

• Regular menstrual cycles (24-35 days) for the past 2 months
• Ovulatory at defined by midluteal progesterone level >3 ng/mL (Day 18-25)
• Belongs to one of the following categories: normal weight (BMI = 18.5-24.9 kg/m2), obese (BMI = 30-39.9 kg/m2) or extremely obese (BMI ≥ 40 kg/m2)
• Participant has no intention of or desire to conceive (e.g., active attempt to become pregnant or in vitro fertilization) for the duration of the study
• Participant agrees to consistently use an effective method of nonhormonal contraception throughout the duration of study, which could include: condoms (male or female) with or without a spermicidal agent, diaphragm or cervical cap with spermicide, non-hormonal intra-uterine devise (IUD), or sterilization.
• Able to give informed consent

Exclusion criteria

• • Known renal or liver disease

• Known pituitary disorder
• Known adrenal disorder
• Known thyroid disorder
• Use of medication known to alter the cytochrome P450 system
• Use of depot-medroxyprogesterone acetate in the previous 6 months or any other hormonal contraceptive in the previous 3 months
• Currently breastfeeding
• Pregnant
• Pregnancy in the prior month
• Known allergy to medication
• Other specific contraindications to LNG EC