Which phase of the human menstrual cycle lasts roughly from days 1 to 14?

The phase of the human menstrual cycle that lasts from approximately days 1 to 14 is the follicular phase. During this time, several follicles in the ovaries begin to mature under the influence of follicle-stimulating hormone (FSH). As these follicles grow, they produce estrogen, which helps to prepare the uterine lining for a potential pregnancy.

Around the middle of this phase, typically at day 14, one dominant follicle becomes ready for ovulation, leading to the release of an egg. The increase in estrogen levels also triggers a surge in luteinizing hormone (LH), which is necessary for ovulation to occur. This entire process is critical for fertility and reproductive health, as it prepares the body for potential conception.

In contrast, the luteal phase occurs after ovulation, the ovulation phase is the brief event of egg release, and the menstrual phase refers to the shedding of the uterine lining if pregnancy does not occur. Each of these phases has its own distinct hormonal changes and physiological processes separate from the follicular phase.