Menstria · the basics
The basics.
The menstrual cycle is the whole monthly process. The period is the bleeding inside it. Five short pages explain the difference, the one mechanism behind it, and the numbers clinicians use.
In this section
5 short pages
01
The cycle and the period are not the same thing
Where the word comes from, and why "cycle" and "period" describe two different things.
2 min read →02
Everything runs through ovulation
A true period is progesterone withdrawal bleeding: no ovulation, no period. Plus the two halves of the cycle.
3 min read →03
What counts as normal
The FIGO System 1 reference ranges for frequency, duration, regularity and volume.
1 min read →04
The same rule explains every state
Adolescence, the pill, pregnancy, breastfeeding, perimenopause and menopause, in one table.
3 min read →05
Why nobody agrees on what "heavy" means
Three definitions of heavy menstrual bleeding, what each was built for, and the measurement problem.
1 min read →