Emergency Contraception in the ED and BMI?

We in the ED may sometimes be asked advice on emergency contraception (EC). The most popular one available is levonorgestrel.  The message from this quick hit article is pretty simple and serves as a simple reminder:

Clinicians should counsel women with BMI ≥ 26 kg/m2 on the potential limitations of oral levonorgestrelfor EC and offer more effective EC methods, including the copper intrauterine device and oral ulipristal acetate1.

In a study by Praditpann et al. it was found that after a single dose of EC, obese-BMI women are exposed to lower concentrations of levonorgestrel and similar concentrations of ulipristal, when compared to normal-BMI women2.

A large study of 6873 women in four randomized trials on EC where Participants took either 1.5 mg of levonorgestrel as either single or two separate doses, up to 120 h after unprotected intercourse showed pregnancy rates of 1.25%in women BMI <25 andpregnancy rate 2.03% in womenBMI>303.


  1. Stowers P. Use of levonorgestrel as emergency contraception in overweight women.Obes Res Clin Pract. 2019 Feb 25. pii: S1871-403X(18)30508-8. doi: 10.1016/j.orcp.2019.01.007.


  1. Praditpann et al. Pharmacokinetics of levonorgestrel and ulipristal acetate emergency contraception in women with normal and obese body mass index. Contraception 95 (2017) 464–469.


  1. Effect of BMI and body weight on pregnancy rates with LNG as emergency contraception: analysis of four WHO HRP studies. Contraception. Volume 95, Issue 1, January 2017, Pages 50-54. https://doi.org/10.1016/j.contraception.2016.08.001




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