This study aims to evaluate long-term outcomes when the etonogestrel contraceptive implant is inserted at an alternative site located over the scapular. The study will evaluate the pharmacokinetics (i.e., drug levels) and side effect profiles of participants who have an etonogestrel contraceptive implant inserted at this alternative scapular site over the course of at least two years.

Inclusion Criteria:

1. Provision of signed and dated informed consent form
2. Stated willingness to comply with all study procedures and availability for the duration of the study
3. Sex assigned at birth must be Female
4. Aged 18-45 years
5. In good general health as evidenced by medical history and no need for regular intensive medical interventions (e.g., inpatient admissions, surgical treatments). The Principal Investigator will be responsible for determining good general health for potential participants with complicated medical histories
6. Interest and willingness to use an etonogestrel contraceptive implant
7. Negative pregnancy test at the time of study enrollment and not planning to become pregnant in the next 36 months
8. Willing to abstain from medications and supplements known to induce/inhibit CYP3A (e.g., rifampin, carbamazepine, ketoconazole, St. John's wort) during the study. In the inducer/inhibitor CYP3A medication is a prescribed medication, individuals must provide the prescriber information for the PI to confirm it is safe for this medication to be abstained during the study
9. Body-mass index ≥18.5kg/m2

Exclusion Criteria:

1. Self-reported contraindications to the use of the ENG implant based on the CDC Medical Eligibility Criteria guidelines for any conditions with a category 3 or 4 recommendation

   1. Current breast cancer or personal history of breast cancer
   2. Malignant liver tumor (hepatocellular carcinoma)
   3. Allergic reaction to any components of the ENG implant

2. Any self-reported known liver conditions that could affect drug metabolism (e.g., cirrhosis, hepatitis)

3. Personal history of deep vein thrombosis (DVT), venous thromboembolism (VTE), or arterial thromboembolism (ATE).

4. Currently taking and unable or unwilling to abstain from any medications or supplements known to be CYP3A inducers/inhibitors.

5. Current use of a progestin-only contraceptive method containing desogestrel or etonogestrel

6. History of spinal deformity (e.g., kyphosis, lordosis)

7. History of shoulder or scapular surgery on the non-dominant side

8. Non-dominant shoulder mobility limitations

9. Previous trauma to the non-dominant scapular region

10. Active skin conditions (e.g., psoriasis) in the non-dominant scapular region

11. Inability to palpate the bony landmarks of the scapula due to adiposity or other body habitus

Serum etonogestrel concentrations and progestin-related side effect outcomes will be shared using NICHD DASH at the conclusion of the study

Study protocol and SAP will be uploaded to clinicaltrials.gov within one year of completion of all study procedures and made available indefinitely

Access to IPD uploaded to NICHD DASH will be handled via the existing DASH access protocols