Ectopic pregnancy with use of progestin-only injectables and contraceptive implants: a systematic review

Use of contraception lowers a woman's risk of experiencing an ectopic pregnancy. In the case of method failure, however, progestin-only contraceptives may be more likely to result in ectopic pregnancies than some other methods such as combined hormonal and barrier contraceptives.

To describe ectopic pregnancy risk associated with use of implants and progestin-only injectable contraceptives through a systematic review of published studies.

We searched electronic databases for articles in any language published through May 2015 describing studies of progestin-only injectables and implants. We also searched bibliographies and review articles for additional studies.

Studies that reported any pregnancies were included in the review. Independent data extraction was performed by two authors based on predefined data fields, and where possible, we calculated the proportion of pregnancies that were ectopic and the ectopic pregnancy incidence rate per 1000 woman-years.

Fifty-three studies of implants and 28 studies of injectables were identified; 79% reported pregnancy location. The proportion of ectopic pregnancy ranged from 0 to 100% with an incidence of 0-2.9 per 1000 woman-years in studies of marketed levonorgestrel implants. Studies of etonogestrel implants and the injectables, depot-medroxyprogesterone acetate and norethisterone enanthate, reported few ectopic pregnancies.

Progestin-only contraceptive implants and injectables protect against ectopic pregnancy by being highly effective in preventing pregnancy overall; however, the absolute risk of ectopic pregnancy varies by type of progestin. Risk of ectopic pregnancy should not be a deterrent for use or provision of these methods.