Tracking Your Cycle as a Vital Sign
The practical version, before the mechanisms
If you want the practical version before the underlying science, this is it. Everything here is explained and cited in the sections that follow.
What to Track
Cycle length — from the first day of one period to the first day of the next. Track for at least 3 months before drawing conclusions about your own pattern.
Flow and duration — how heavy, how many days. "Heavy" is genuinely subjective, but a sudden change from your own normal is informative even without a precise measurement.
Symptoms and their timing within the cycle — mood, pain, energy, breast tenderness. Patterns that cluster predictably in the same phase each month (Section 1) are usually benign; patterns that are severe, unpredictable, or worsening are worth flagging.
When to Raise It With a Doctor
| Pattern | Worth raising because |
|---|---|
| Cycles consistently shorter than 21 or longer than 35 days | Outside the range considered typical — see Section 1 |
| Periods stop for 3+ months without pregnancy | Could indicate a range of causes from stress to PCOS to low energy availability — see Sections 4 & 6 |
| Bleeding heavy enough to disrupt daily life | "Heavy" has a clinical definition, and there are effective treatments — see Section 6 |
| Pain severe enough to affect daily function, not just discomfort | Common, but not something to just live with — see Sections 5 & 6 |
| New acne, excess hair growth, or unexplained weight changes alongside cycle changes | Classic PCOS pattern — see Section 4 |
The core reframe
None of this is about comparing your cycle to a textbook average. It's about knowing your own pattern well enough to notice a genuine change — which is a far more useful signal than any single number.