Fertility · 3 min read

Fertile window explained

The fertile window is the part of a cycle when pregnancy is most likely. For people trying to conceive, it can help to combine calendar patterns with body signs instead of relying on a single prediction.

Several fertility signals shown together over time without an exact prediction — Calendar timing and body signs can add context, but none guarantees an exact ovulation day.

Dela does not provide contraception, medical diagnosis, or medical fertility advice. Use this guide as education, and talk with a clinician about your own health history.

What the fertile window means

Ovulation usually happens once in a cycle. The days of highest probability generally come before and around ovulation, but calendar dates are not exact. ACOG explains that pregnancy can occur from intercourse up to five days before ovulation through one day after, because sperm may survive several days and an egg may survive about 24 hours.

Signals that can add context

Cycle history

Past cycle lengths can help estimate a future window, but they are still estimates. Stress, illness, travel, postpartum changes, and other factors can shift timing.

Cervical fluid

Some people notice cervical fluid become clearer, wetter, or stretchier near ovulation. Logging this can make patterns easier to see over time.

Basal body temperature

Basal body temperature often rises after ovulation. A sustained shift can add retrospective evidence that ovulation may have happened, but temperature alone cannot confirm an exact day and is less useful for predicting fertile days in advance.

Ovulation tests

Ovulation predictor kits can detect a hormone surge that often happens before ovulation. Logging test results beside symptoms and cycle history can give a fuller picture.

How Dela helps

Dela brings these signals into one private place: cycle history, fertile signs, temperature, ovulation tests, symptoms, and notes. The app can help you review timing with more context while keeping your reproductive data under the controls described in Dela's privacy policies.