If a woman’s menstrual cycle is regular, ovulation occurs about 14-16 days before the next menstrual period. If the menstrual cycle is 45 days, the follicular phase will be longer, ovulation is relatively fixed in relation to the next menstrual period, is in the menstrual cycle of the 29th-31st day, after ovulation will enter the luteal phase, luteal phase lasts for about 2 weeks, if there is no conception after ovulation, luteal body will atrophy, estrogen, progesterone withdrawal, the endometrium loses the hormonal support of the shedding occurs, and then the menstrual period. Different lengths of menstrual cycles, the time of ovulation is not the same, because from the primary follicle development to mature follicle time is not the same, resulting in the length of the entire menstrual cycle, but the luteal phase after ovulation is roughly the same, in about 2 weeks.