Cycle and ovulation
Cycle day 1 is the first day of proper bleeding, not spotting. Clinics count from this day when scheduling baseline scans, blood tests and the start of stimulation medicines, so recording it accurately matters. If you are unsure whether light bleeding counts, ask your clinic rather than guessing.
Also known as: day 1, CD1, first day of period
Related checklists
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.