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).
Menstrual cup investigated whether silicone menstrual cups are a viable alternative to tampons and found that approximately 91% of women in the menstrual cup group said they would continue to use the cup and recommend it to others. In a 1991 clinical study involving 51 women, 23 of the participants (45%) found rubber menstrual cups to be an acceptable way of managing menstrual flow. In a randomized controlled feasibility study in rural western Kenya, adolescent primary school girls were provided with menstrual cups or sanitary pads instead of traditional menstrual care items of cloth or tissue. Girls provided with menstrual cups had