Ovarian follicles can be thought of as tiny little cases in the ovaries that hold immature eggs. Many of the two million eggs women are born with are reabsorbed by the body during childhood, so by the time of puberty, women are left with around 400,000 to 500,000 eggs.
Hormones trigger follicles to grow during the follicular phase. In a natural cycle, normally only one dominant follicle goes on to mature fully and release an egg.
Ovulation occurs when the dominant follicle ruptures to release an egg which is then collected by the fimbrial end of the fallopian tube and delivered into the tube.
Some women can tell they’re ovulating when they experience symptoms such as breast tenderness, heavier and more opaque vaginal discharge, and a feeling of tightness in the abdomen, whilst others have no symptoms.
Those trying to conceive sometimes keep temperature charts or use apps to indicate when they have ovulated, others purchase ovulation kits and test their urine.
Across the population, the luteal phase lasts for a fairly consistent 14 days.
During this time, the uterine lining (endometrium) develops to receive a fertilised egg. If conception doesn’t happen, the lining sheds and women experience a period.
The conditions for a true period to occur (full bleed, not spotting) require a rise and fall in hormone levels which happens with the progression of ovulation.