- i. Women with menstrual cycle length of less than 24 or more than 37 days; or with spontaneous irregular menstrual cycle length with intra-individual variations of more than 5 days ii. Currently pregnant as confirmed by positive high-sensitivity urine pregnancy test iii. Women planning pregnancy within their months of study participation iv. Currently breast-feeding or within 30 days of discontinuing breast feeding v. Current use of a hormonal IUD, or other hormonal contraception (including oral contraceptives, contraceptive vaginal rings, contraceptive patches, or contraceptive implants) within 30 days prior to screening. NOTE: Discontinuation of hormonal contraception or removal of implanted hormonal contraceptives must have been for personal reasons unrelated to the purpose of enrollment in this study.