Use of the Etonogestrel-Releasing Contraceptive Implant

Jaclyn Grentzer; Colleen McNicholas; Jeffrey F Peipert


Expert Rev of Obstet Gynecol. 2013;8(4):337-344. 

In This Article

Special Populations

As mentioned in the preceding section, ENG implant can be used in women who are postabortion, postpartum and lactating. This method is also an ideal option for other special populations of women including adolescents, overweight and obese women, and women with contraindications to estrogen use.

Young women and adolescents are at high risk for unintended pregnancy. In fact, 49% of adolescents who have given birth are pregnant again within 1 year.[45] Previously, adolescents have been regarded as an inappropriate population to receive LARCs.[46] However, given their contraceptive and noncontraceptive benefits, adolescent women are an ideal population for ENG implants. In the Contraceptive CHOICE Project, participants received the reversible contraceptive method of their choice free of charge. In women aged 14–20 years, 23% elected the ENG implant. In the teens between 14 and 17 years of age (n = 214), 43% chose ENG implant.[47] This study demonstrated that the ENG implant is an acceptable method among adolescents. In addition, the CHOICE project reported that 82% of 14–19 year olds were still using the ENG implant at the 12-month time point. This continuation rate was similar to the 20- to 25-year-old group (80%) and the 26 and older group (84%). By contrast, 12-month continuation of non-LARC methods (e.g., oral contraceptives, the contraceptive patch, ring and DMPA) were less than 50% in 14–19 year olds, and 52–53% in women over 19 years of age.[48,49]

Lewis et al. compared 73 girls and young women, 12–18 years of age, who self-selected the ENG implant to 40 adolescents who selected oral contraceptives or DMPA and 24 teens who selected barrier methods or nothing. By 24 months postpartum, 35% of teenagers had conceived. Implant users were more likely to continue their contraceptive method at 24 months postpartum. As a result, they were less likely to become pregnant, when compared with the other two groups.[50] Similar results were seen in a study by Tocce et al. Of 396 patients between 13 and 23 years of age, 43% chose to receive the ENG implant in the immediate postpartum period. Implant users were compared with those who chose an alternate method or no method of contraception. Women who received the implant immediately postpartum were found to have a 12-month pregnancy rate of 2.5% compared with a rate of 18.6% in women choosing an alternative method of contraception.[51]

While there is pharmacokinetic data that suggest that serum concentration of ENG is lower in obese women compared with normal weight women, there is no clinical data to suggest that these women are at increased risk of contraceptive failure. The Contraceptive Choice Project evaluated 1168 implant users, 28% (n = 327) of which were classified as overweight and 35% (n = 409) obese and found no increased risk of failure by BMI.[15]

The ENG implant can be used safely in nearly all women, including those who may not be candidates for other estrogen-containing methods of contraception. The US Contraceptive Medical Eligibility Criteria (MEC) discourages the use of estrogen-containing methods in women with some common health conditions (history of thromboembolic disease, hypertension, smokers aged >35 years).[101] The implant can be used safely in these women. There are very few absolute contraindications to the ENG implant. The US MEC categorizes each contraceptive method and medical condition according to potential advantages and risks. A category 1 implies 'no restriction' of use. Category 2 is a condition in which the advantages of the method outweigh potential risks. A condition where the theoretical or proven risks outweigh the advantages is category 3. Category 4 is reserved for conditions that represent an unacceptable health risk if the contraceptive method is used. The only medical condition for which the US MEC categorizes the implant as a category 4 is current breast cancer.[52] Hypersensitivity to any components of the ENG implant and pregnancy are the only other absolute contraindications. The only conditions listed as category 3 for the implant are benign and malignant liver tumors, severe cirrhosis, past breast cancer and no evidence of disease for 5 years, systemic lupus with positive (or unknown) antiphospholipid antibody and unexplained vaginal bleeding (before evaluation). Most experts do not agree with the statement in the manufacturer's package insert that women with a current venous thromboembolism (deep venous thrombosis or pulmonary embolism) are not candidates for the ENG implant. Progestin-only contraceptive methods are believed to be safe for women with thromboembolic disease.[52]