Menstrual cycle shortest and longest cycle lengths is considered very irregular. The average menstrual cycle lasts 28 days. The variability of menstrual cycle lengths is highest for women under 25 years of age and is lowest, that is, most regular, for ages 25 to 39. Subsequently, the variability increases slightly for women aged 40 to 44. The luteal phase of the menstrual cycle is about the same length in most individuals (mean 14.13 days, standard deviation 1.41 days) whereas the follicular phase tends to show much more variability (log-normally distributed with 95% of individuals having follicular phases between 10.3 and 16.3 days).
Heavy menstrual bleeding whose symptoms are not well-controlled. Approximately 53 in 1000 women are affected by AUB. A normal menstrual cycle is 21–35 days in duration, with bleeding lasting an average of 5 days and total blood flow between 25 and 80 mL. Heavy menstrual bleeding is defined as total menstrual flow >80ml per cycle, or soaking a pad/tampon every 2 hours or less. Deviations in terms of frequency of menses, duration of menses, or volume of menses qualifies as abnormal uterine bleeding. Bleeding in between menses is also abnormal uterine bleeding and thus requires further evaluation. Complications of heavy menstrual bleeding could