Cycle and ovulation
A menstrual cycle runs from day one of bleeding to the day before the next period starts. Cycles between about 21 and 35 days are considered within the normal range, and some natural variation from month to month is expected. Cycles that are consistently very short, very long, absent or unpredictable are worth investigating, because they often indicate ovulation is irregular.
Also known as: period cycle, cycle length, menstrual cycles
Planning tools
Sources
- Healthdirect Australia (healthdirect.gov.au)
- Your Fertility, a national public education programme (yourfertility.org.au)
Last reviewed: 10 September 2026. Written by the Antega Editorial Team. General information only — always follow the advice of your own clinic, doctor or pharmacist.