the Menstrual Phase

The menstrual phase begins on your first day of full bleeding (this is Day 1 of your cycle) and lasts until bleeding stops. During this phase, if pregnancy doesn’t occur, the body sheds the uterine lining that built up during your previous cycle.

In the menstrual phase, estrogen & progesterone are typically low, which triggers the shedding of the lining. Typically the menstrual phase lasts 5-7 days.

the Follicular Phase

Next, there is the follicular phase. This phase overlaps with menstruation and continues until bleeding has finished. In this phase, FSH (follicle stimulating hormone) levels increase, which stimulates the growth of follicles and increases the amount of estrogen to rebuild the uterine lining. The typical length of your follicular phase is 1-13 days.

Ovulation

This leads to ovulation. Around day 14 (with individual variations) a mature egg is released from the ovary. In this phase, a surge of LH (luteinizing hormone) is triggered by increasing levels of estrogen, which causes the release of an egg from the follicle.

the Luteal Phase

Lastly, the luteal phase. The luteal phase lasts from cycle day 15-28 (or until the day before your next bleed). During this phase, the ruptured follicle forms the corpus luteum, which secretes progesterone to prepare the uterine lining for implantation of a fertilized egg.

In this phase, progesterone increases and estrogen remains slightly elevated to maintain the uterine lining. If fertilization doesn’t happen, estrogen and progesterone levels drop and menstruation occurs (the beginning of a new cycle!)