Your Cycle: A User's Guide

Know Your Phases

Not sure when day one of your cycle is? Can't tell the difference between the luteal and follicular phases? We hear you! The following simple chart spells out everything you need to know.

The Follicular Phase is the beginning of your cycle (day one refers to the first day of your period). Low levels of estrogen and progesterone cause the lining of your uterus to shed. In the first half of this phase, the level of follicle-stimulating hormone (FSH) increases slightly and a new egg develops. During the last part (typically starting on day seven), the ovaries begin to produce more estrogen and the uterine lining begins to thicken.

The Ovulatory Phase starts around day 10 of your cycle, with a surge in FSH and luteinizing hormone (LH), which prompts the egg to be released (ovulation) around day 14. Estrogen peaks and the level of progesterone increases.

The Luteal Phase is when levels of LH and FSH begin to ebb, starting around day 15. The uterine lining finishes thickening. If the egg is not fertilized, the levels of progesterone and estrogen decrease through day 28 and then your period begins. Back to day one.