On this page 4 sections
Quick answer
- Typical use is about 76% effective; perfect use 91–99%.
- Needs daily tracking of three signs and expert teaching.
- Cycle-tracking apps (including this one) aren’t contraception.
- There are no guaranteed “safe days”.
Fertility awareness (also called natural family planning) means tracking your body’s signs to work out when you’re fertile, then avoiding sex or using condoms on those days. It’s hormone-free, which appeals to lots of people. But it needs honesty about how well it works.
With perfect use and expert teaching, the NHS estimates 91–99%. The gap is big because perfect use is hard: daily readings, interpreting them correctly, and no unprotected sex on any possibly fertile day.
What it involves
- Tracking three signs daily: Basal body temperature, cervical mucus and cycle length
- Learning from a trained teacher – ideally for 2–3 cycles, using other contraception meanwhile
- Avoiding sex or using condoms throughout the fertile window
Who it’s harder for
- Irregular cycles
- Recently stopped hormonal contraception or recently had a baby
- Shift work, poor sleep or frequent illness (throws BBT off)
- Anyone for whom pregnancy would be a big problem right now
MythSex on your period is always safe.
Sperm can survive for days, and with shorter cycles ovulation can come soon after a period. No day is guaranteed safe.
MythWithdrawal (pulling out) is a fertility awareness method.
It isn’t – and it’s unreliable, as pre-ejaculate can contain sperm.
Sources
Written by the Splash teamSources checked
This is general information, not medical advice. Splash can’t diagnose. If you’re worried, talk to a GP, pharmacist or sexual health clinic. In an emergency call 999 (UK) or 911 (US). How we write and check articles.