We analyzed the duration of menstrual periods of roughly 19000 fertility/ovulation charts on FertilityFriend.com.
This statistical study counted the days of consecutive bleeding or spotting at the start of each cycle.
The descriptive stats for this sample are:
|Sample Size:||19933 Charts.|
We found that 66% of the sample's charts include one or more days of spotting mostly at the end of the period. Further analysis showed that the median number of days of spotting is 1 day.