Understand your cycle
Plain-language reads on how cycles work and how to track them well, from the team behind Plum. Every claim links back to sources like ACOG, the NHS, Mayo Clinic, and the NIH, and none of it is a substitute for advice from your own clinician.
How long is a normal menstrual cycle?
Average cycle length, the normal range for adults and teens, what makes cycles vary, and the changes that mean it is time to talk to a clinician.
Read the guideWhat is the fertile window and how is it calculated?
The fertile window is the handful of days each cycle when pregnancy is possible. How apps and clinicians estimate it, and where estimates fall short.
Read the guideIrregular periods: common causes and when to see a doctor
From stress and travel to PCOS and thyroid problems, the common reasons periods go irregular, and the symptoms that deserve a visit to a clinician.
Read the guideHow to choose a period tracker that respects your privacy
Period apps hold some of your most sensitive data. A practical checklist for judging a tracker’s privacy by what its policy actually says.
Read the guide