If levonorgestrel emergency contraception fails, there may be an increased risk of ectopic pregnancy (when a fertilised egg implants itself outside of the womb) within the same conception cycle in specific situations, large study of Chinese women in Scientific Reports this week suggests. However, in other circumstances levonorgestrel emergency contraception does not seem to increase the risk of future ectopic pregnancy. The findings highlight the importance of offering clear guidance on how to take this form of contraception and ensuring that women are informed about potential risks associated with its use.

Cases of ectopic pregnancy following levonorgestrel emergency contraception failure have been reported in China and other countries. To explore the potential association between ectopic pregnancy risk and levonorgestrel emergency contraception use, He-Feng Huang and colleagues analyzed over 7,000 Chinese women categorized as either ectopic pregnancy patients, women with an intrauterine (normal) pregnancy, or non-pregnant women. Their analyses reveal that previous use of levonorgestrel emergency contraception does not increase the risk of ectopic pregnancy in future conception cycles. However, in cases where the emergency pill has failed, risk of ectopic pregnancy is increased in women who continue to have unprotected sex and use levonorgestrel emergency contraception repeatedly in the same conception cycle, compared with women who had no further intercourse.

The authors conclude that a better understanding of the risk of ectopic pregnancy associated with levonorgestrel emergency contraception failure could help to optimize the way in which this form of contraception is used.