Perimenopause and Oligomenorrhea
When a young girl experiences the first menstrual cycle, it would take her a couple of years until periods start to have a persistent pattern. At first, irregular periods and bleeding, which is lighter or heavier than the latest month are not uncommon. As they grow, hormones often stabilize. These changes in menstrual cycles would also occur when people enter menopause. The hormonal variations happening to facilitate this process might result in periods, which come later or sooner than expected. They can also vary in heaviness and duration. [4]
