This may be a sign that you are in early menopause. Some women start to experience fluctuations in estrogen levels in their 40s. The fluctuations present with menstrual cycle irregularities.
As ovulation becomes more unpredictable, the length of time between periods may be longer or shorter, your flow may be light to heavy, and you may skip some periods. If you have a persistent change of seven days or more in the length of your menstrual cycle, you may be in early perimenopause. If you have a space of 60 days or more between periods, you're likely in late perimenopause.