Anovulatory cycle
While the normal menstrual cycle in the human typically lasts 4 weeks (28 days, range 24–35 days) and consists of a follicular phase, ovulation, and a luteal phase, followed by either menstruation or pregnancy, the anovulatory cycle has cycle
lengths of varying degrees. In many circumstances, menstrual intervals are prolonged exceeding 35 days leading to oligomenorrhea (cycle >35 – 180 days interval), or even longer, amenorrhea. In other cases, menstruation may be fairly regular (eumenorrhea), or more frequent (intervals < 21 days), or there may be a loss of menstrual pattern (menorrhagia, dysfunctional uterine bleeding).
Estradiol valerate/hydroxyprogesterone caproate
EV/OHPC as a combined injectable contraceptive has a relatively short duration and is associated with a high incidence of menstrual irregularity, for instance polymenorrhea (short and hence fast cycles). This may be unacceptable to many women. Twice-monthly administration of half doses has not been found to improve breakthrough bleeding, though cycle length increased to 20 to 24 days.