7. Females of childbearing potential (FCBP) participating in the study are to use highly effective methods of birth control during study participation and for 112 days (approximately five times the mean terminal half-life of sotatercept [23 days] based on multiple-dose PK data) following the last dose of sotatercept. FCBP must have a negative serum beta-human chorionic gonadotropin (β-HCG) pregnancy test within 3 days of sotatercept dosing (study Day 1). Subjects must be counseled concerning measures to be used to prevent pregnancy and potential toxicities prior to the first dose of sotatercept. A FCBP of childbearing potential is a sexually mature woman who has not undergone a hysterectomy or bilateral oophorectomy or who has not been postmenopausal for at least 24 consecutive months (ie, who has had menses at some time in the preceding 24 months).