A systematic review and meta-analysis of the prevalence and association between levonorgestrel and ectopic pregnancy

The use of levonorgestrel emergency oral contraceptives (EOCs) is one of the factors that may be associated with ectopic pregnancy. We aimed to investigate the incidence of ectopic pregnancy in EOC users and the association between EOCs and ectopic pregnancy.

We searched for articles that provided the incidence of and the association between levonorgestrel EOCs and ectopic pregnancy in women of reproductive ages in CINAHL Complete, Medline, OpenDissertations, Scopus, Science Direct, and Thai Journal Online. The risk of bias was assessed by Risk Of Bias In Non-randomized Studies or Risk of Bias 2. A meta-analysis was conducted using the random-effects model.

We retrieved 1839 nonredundant articles from the systematic search. The meta-analysis showed that the prevalence of ectopic pregnancy was not statistically different from zero (pooled prevalence estimate = 0.029%; 95%CI: -0.006, 0.065; N = 9; I² = 0) and rare. In addition, levonorgestrel EOCs increased the risk of ectopic pregnancy (OR = 6.17; 95%CI: 3.78, 10.08; N = 5; I² = 43%).

Women with extrauterine or ectopic pregnancy had higher odds of using levonorgestrel emergency oral contraceptives than those with intrauterine pregnancy. However, the prevalence of ectopic pregnancy is rare.