The etonogestrel subdermal implant has been available worldwide for more than 15 years. The action of etonogestrel subdermal implant is principal via suppression of ovulation, but it also has effects on cervical mucus and in some women induces suppression of endometrial proliferation. Several studies have confirmed its high efficacy and convenience. The uterine bleeding problems and in particular irregular bleeding and amenorrhea are major side effects of etonogestrel subdermal implant. A considerable number of patients request early removal due to bleeding changes. Amenorrhea occurs in about 22% in etonogestrel subdermal implant users. Despite the presence of many studies that reported the prevalence of etonogestrel subdermal implant-associated bleeding, little is known about the predictive factors affecting menstrual bleeding patterns especially amenorrhea after etonogestrel subdermal implant insertion. These predictive factors should be provided prior to the etonogestrel subdermal implant insertion which may improve acceptance and continuation of etonogestrel subdermal implant.

Inclusion Criteria:

1. Women aged between 18 and 40 years.
2. Women who are not lactating.
3. Non-pregnant women
4. Women have regular menstrual cycles every 21-35 days with a typical cycle length variation of no more than 5 days.
5. Women who will ESI only for pregnancy prevention for at least 12 months.
6. Have not any medical or gynecologic problems.

Exclusion Criteria:

1. Women with any contraindications for progesterone-only contraception in accordance with WHO eligibility criteria.
2. Refuse participation in the study.