Ovulation · 5 minute read
Ovulation: what actually happens
The hormone surge, egg release, fertile timing, and the difference between predicting and confirming ovulation.
Evidence-informed · Editorial review August 2026 · Links to trusted sources are available in the interactive app
Egg release follows a hormone signal
A surge in luteinizing hormone prompts the dominant ovarian follicle to release an egg. Ovulation is an event, not a multi-day phase, and the exact timing can shift even in otherwise regular cycles.
The fertile window begins before ovulation
Sperm may remain capable of fertilization for several days, while the egg has a much shorter life after release. Pregnancy can therefore result from sex in the days before ovulation as well as around ovulation itself.
Different signs answer different questions
Cervical mucus and urinary LH tests may suggest ovulation is approaching. A sustained basal body temperature shift can support that ovulation already occurred. No single home sign is perfect.