A well-designed pharmacokinetics (PK) study may identify the physiologic basis for observed
differences in levonorgestrel emergency contraception (LNG-EC) and ulipristal acetate
emergency contraception (UPA-EC) failure rates in women with normal and obese BMI. The
investigators propose a study to compare serum LNG and UPA levels after administration of a
single-dose of LNG-EC or UPA-EC. The investigators hypothesize that there will be no
difference in PK parameters between women with normal BMI and obese women.