Pregnancy, fertility
Finding your fertile window without guessing
Three signals actually predict ovulation — mucus, temperature and LH tests. Here is what each one tells you, and which one arrives too late.
Reviewed against NHS, 2 mins read, published
The fertile window is roughly six days: the five before ovulation, plus the day itself. Counting squares on a calendar predicts it badly, because the first half of your cycle moves.
The signs, in order
Cervical mucus is the signal that arrives in advance. As oestrogen rises it becomes clearer and more slippery, and that change is your notice that the window is opening.
It's difficult to pinpoint exactly when ovulation happens, but in most women it happens around 10 to 16 days before the next period.
Tests and temperature
Temperature works the other way round. It rises after ovulation, so it confirms what already happened — useful for learning your own pattern over a few months, useless for catching this one.
Urine tests pick up the hormone surge a day or so before release, which makes them the most precise same-cycle tool you can buy. Mucus plus tests gives you the window; temperature tells you whether your pattern is steady.
Quick summary
- The window: about six days: the five before ovulation, plus the day itself
- In advance: clearer, more slippery cervical mucus
- Same cycle: urine tests catch the hormone surge a day or so before
- After the fact: temperature confirms ovulation has happened
- Ask for help: after a year of trying, or six months if you are over 35
