EC PK in Women With Normal and Obese BMI

Inclusion Criteria: * Women aged 18-45 years * English-speaking * BMI 18.5-24.9 kg/m2 or obese BMI 30.0-39.9 kg/m2 * Regular menstrual cycles * No use of medroxyprogesterone acetate at least 6 months prior to study enrollment, unless resumption of two menstrual cycles * No use of levonorgestrel intrauterine system (levonorgestrel-IUS), etonogestrel implant or combined hormonal contraception at least one month prior to the study and resumption of one menstrual cycle * Women who are postpartum or post-abortion will be included if they have had at least one menstrual cycle since their last pregnancy Exclusion Criteria: * Prior allergic reaction to LNG-EC or UPA-EC * Use of hormonal emergency contraception within the past month * Women who are currently pregnant or who are currently breastfeeding * History of cancer other than non-melanoma skin cancer * Medical or surgical conditions or conditions requiring therapies known to impact sex steroid production or metabolism * Use of HAART therapy for management of HIV infection * Concomitant use of CYP3A4 inducers like rifampin, barbiturates, carbamazepine, lamotrigine, bosentan, felbamate, griseofulvin, oxcarbazepine, phenytoin, St. John's Wort and topiramate * Current participation in any other trial of an investigational medicine or device in the three months leading up to this study