Cycle & hormone glossary

Clear, quick definitions for the cycle and hormone terms worth knowing.

• Menstrual cycle — The menstrual cycle is the roughly monthly hormonal rhythm that prepares the body for a possible pregnancy, counted from the first day of one period to the first day of the next.
• Menstrual phase — The menstrual phase is days 1 to about 5 of your cycle, when the uterine lining sheds as your period and estrogen and progesterone are at their lowest.
• Follicular phase — The follicular phase runs from the first day of your period until ovulation, when rising estrogen matures a follicle in the ovary.
• Ovulatory phase — The ovulatory phase is the short window of about three days around ovulation, when estrogen and testosterone peak and an egg is released.
• Luteal phase — The luteal phase is the time between ovulation and your next period, usually 11 to 17 days, when progesterone rises and then falls.
• Ovulation — Ovulation is the release of a mature egg from the ovary, usually about 14 days before your next period.
• Fertile window — The fertile window is the roughly six days each cycle when conception is possible: the five days before ovulation plus ovulation day.
• Infradian rhythm — The infradian rhythm is a biological cycle longer than 24 hours. In people who menstruate, it is the roughly monthly hormonal pattern of the menstrual cycle.
• Cycle syncing — Cycle syncing is the practice of adjusting your food, workouts, work, and rest to match the four phases of your menstrual cycle.
• Estrogen — Estrogen is the main hormone of the cycle's first half. It rises through the follicular phase, peaks at ovulation, and supports energy, mood, and skin.
• Progesterone — Progesterone is the dominant hormone of the luteal phase. It rises after ovulation to support a possible pregnancy, then falls to trigger your period.
• Testosterone — Testosterone is present in smaller amounts across the cycle and peaks around ovulation, boosting libido, confidence, and motivation.
• Follicle-stimulating hormone (FSH) — FSH is a hormone from the pituitary gland that stimulates ovarian follicles to grow in the follicular phase.
• Luteinizing hormone (LH) — LH is the hormone whose mid-cycle surge triggers ovulation, the release of a mature egg.
• PMS (premenstrual syndrome) — PMS is the cluster of physical and emotional symptoms — mood changes, bloating, cravings, fatigue — that appear in the luteal phase before your period.
• PMDD (premenstrual dysphoric disorder) — PMDD is a severe form of PMS with intense mood symptoms — depression, anxiety, irritability — in the luteal phase that disrupt daily life.
• Seed cycling — Seed cycling is the practice of eating specific seeds in each half of the cycle — flax and pumpkin in the follicular phase, sunflower and sesame in the luteal phase — to support hormones.
• Menstruation — Menstruation, or your period, is the shedding of the uterine lining at the start of the cycle, typically lasting 3 to 7 days.
• Luteal phase length — Luteal phase length is the number of days from ovulation to your next period, usually 11 to 17 days, and is the most stable part of the cycle.
• Anovulation — Anovulation is a cycle in which no egg is released. Periods may still occur but without ovulation.
• Corpus luteum — The corpus luteum is the structure that forms from the follicle after ovulation and produces progesterone during the luteal phase.
• Cervical mucus — Cervical mucus is fluid from the cervix whose texture changes across the cycle. Around ovulation it becomes clear and stretchy, like raw egg white.
• Basal body temperature (BBT) — Basal body temperature is your lowest resting body temperature, taken first thing in the morning. It rises slightly after ovulation.
• Hormonal acne — Hormonal acne is acne that flares with cycle hormone shifts, often appearing on the chin and jaw in the luteal phase before a period.
• Cortisol — Cortisol is the body's main stress hormone. Chronically high cortisol can disrupt the cycle and worsen PMS symptoms.