Study of Relugolix Alone and Relugolix Combined With Hormonal Add-Back Therapy in Healthy Premenopausal Female Participants

Inclusion Criteria: 1. Pre-menopausal female between 18 and 48 years of age. 2. E2, P, LH and FSH concentrations within 0.5x of the lower limits of normal range and 2x of the upper limits of normal upper limits of normal range (ULN) 3. Regular menstrual periods for the 3 months prior to study enrollment 4. Body weight ≥ 45 killograms (kgs) and body mass index (BMI) of 20 to 36 5. Capable of giving written informed consent Exclusion Criteria: 1. Pregnancy 2. Lactating Females 3. Any contraindication to the treatment with E2 and NETA 4. Use of the following medications in the 3 months prior to screening: injectable hormonal contraceptives, sex hormone medications or danazol 5. Use of the following medications in the 6 months prior to screening: injectable gonadotropin-releasing hormone agonists, hormonal, or non-hormonal intrauterine devices 6. History of sensitivity to any of the study medications of components thereof or history of drug 7. Significant gynecological, endocrine, metabolic or other health conditions 8. History of regular alcohol consumption within 6 months of study