Curr Med Res Opin. 2015 Oct 27:1-8.

Impact of bodyweight/body mass index on the effectiveness of emergency contraception with levonorgestrel: a pooled-analysis of three randomized controlled trials

Gemzell-Danielsson K, Kardos L and von Hertzen H


Objective: A pooled analysis of two randomized controlled trials (RCTs) suggested that increased bodyweight and body mass index (BMI) may be associated with a greater probability of pregnancy. To address this issue we investigated whether higher bodyweight and/or BMI negatively impacted the risk of pregnancy in women receiving LNG-EC (levonorgestrel - emergency contraception) after unprotected sexual intercourse in a pooled analysis of three large multinational RCTs conducted by the World Health Organization (WHO).

Methods: A pooled analysis of three double-blind, multinational RCTs conducted by the WHO to investigate the efficacy of LNG-EC in the general population. All analyses were done on the per-protocol set (PPS) which included 5812 women who received LNG-EC within 72 hours following unprotected sexual intercourse. The analysis was based on logistic regression, with pregnancy as the outcome. BMI and weight were represented in the same model.

Results: A total of 56 pregnancies were available for analysis in the PPS. Increasing bodyweight and BMI were not correlated with an increased risk of pregnancy in the studied population. A limitation of this study is that despite the large study population in the pooled analysis there were relatively small numbers of women in the high-BMI and high-bodyweight subgroups.

Conclusions: LNG-EC is effective for preventing pregnancy after unprotected intercourse or contraceptive failure and no evidence was found to support the hypothesis of a loss of EC efficacy in subjects with high BMI or bodyweight. Therefore, access to LNG-EC should not be limited only to women of lower bodyweight or BMI.

Comment: As a practitioner one is often asked by clients who have some degree of obesity whether there is sufficient hormone in the medication for them. This nice analysis clearly shows that there is no reason for concern. Levo-norgestrel emergency contraception works well in women with a higher BMI. (And, of course, one can always use an IUD as alternative EC.) (HMV)