A Study to Evaluate the Safety and Efficacy of Elagolix for the Management of Heavy Menstrual Bleeding Associated With Uterine Fibroids in Premenopausal Women

Inclusion Criteria:

* Participant at the time of screening has a diagnosis of uterine fibroids documented by a pelvic ultrasound \[transabdominal ultrasound (TAU) and transvaginal ultrasound (TVU)\].
* Participant has HMB associated with uterine fibroids as evidenced by menstrual blood loss (MBL) \> 80 mL during 1 menses in screening as measured by the alkaline hematin method.
* Participant has negative urine and/or serum pregnancy test in Washout (if applicable) and/or Screening and just prior to first dose.
* Participant has an adequate endometrial biopsy performed during Screening, the results of which show no clinical significant endometrial pathology.

Exclusion Criteria:

* Participant has screening pelvic ultrasound or saline infusion sonohysterography (SIS) or magnetic resonance imaging (MRI; if SIS is unevaluable), results that show a clinically significant gynecological disorder.
* Participant has history of osteoporosis, osteopenia, or other metabolic bone disease.
* Participant has clinically significant abnormalities in clinical chemistry, hematology, or urinalysis.
* Participant has a history of major depression or post-traumatic stress disorder (PTSD) episode within 2 years of screening, OR a history of other major psychiatric disorder at any time (e.g., schizophrenia, bipolar disorder).
* Participant is using any systemic corticosteroids for over 14 days within 3 months prior to Screening or is likely to require treatment with systemic corticosteroids during the course of the study. Over the counter and prescription topical, inhaled, intranasal or intra-articular injectable (for occasional use) corticosteroids are allowed.