Updated by: Arabinda Naik
Follicular Phase:
Timing: The follicular phase typically occurs during the first half of the menstrual cycle, starting on the first day of menstruation and lasting until ovulation. This phase can vary in length from person to person but is generally around 10-14 days.
Hormones: During the follicular phase, the pituitary gland releases follicle-stimulating hormone (FSH), which stimulates the growth and development of ovarian follicles (tiny sacs in the ovaries that contain immature eggs). The primary hormone produced during this phase is estrogen, which increases gradually and helps thicken the uterine lining (endometrium) in preparation for potential implantation of a fertilized egg.
Ovulation: The follicular phase ends with ovulation, which is the release of a mature egg (ovum) from one of the ovarian follicles. Ovulation typically occurs around the middle of the menstrual cycle.
Luteal Phase:
Timing: The luteal phase follows ovulation and lasts for the second half of the menstrual cycle, leading up to the next menstruation. It is generally a more consistent duration of around 12-14 days for most women.
Hormones: After ovulation, the empty ovarian follicle transforms into a structure called the corpus luteum, which secretes hormones, primarily progesterone. Progesterone is responsible for maintaining the uterine lining and creating a favorable environment for a potential embryo to implant in case fertilization occurs. Estrogen levels also remain relatively high during this phase.
Uterine Changes: The uterine lining becomes thick and vascularized during the luteal phase, preparing to support a developing embryo. If fertilization and implantation do not occur, progesterone and estrogen levels drop, leading to the shedding of the uterine lining and the start of menstruation.