stˈʌdiz ʌv tˈuː.fˈaɪv ˌɛmdʒˈiː ˈoːɹəl dʒˈɛstɹɪnˌɑːn twˈaɪs pɜː wˈiːk hæv fˈaʊnd ɐ ɹˈeɪt ʌv ɐmˈɛnɔɹˌiə ʌv fˈɪfti tə fˈɪfti ˈeɪt pɚsˈɛnt, wˌaɪl ɐ stˈʌdi ʌv fˈaɪv ˌɛmdʒˈiː ˈoːɹəl dʒˈɛstɹɪnˌɑːn pɜː dˈeɪ fˈaʊnd ɐ ɹˈeɪt ʌv ɐmˈɛnɔɹˌiə ʌv wˈʌnhˈʌndɹɪd pɚsˈɛnt.
Studies of 2.5 mg oral gestrinone twice per week have found a rate of amenorrhea of 50 to 58%, while a study of 5 mg oral gestrinone per day found a rate of amenorrhea of 100%.