--- title: "Natural family planning and fertility awareness" description: "What fertility awareness involves, why you need training, how well it works, and why a period app is not contraception. Includes when to get help." url: "https://myruva.co/learn/fertility-awareness-methods" language: "en-GB" topic: "Contraception" published: "2026-10-18" updated: "2026-10-19" author: "Ruva team" reading_minutes: 4 --- # Natural family planning and fertility awareness What fertility awareness involves, why you need training, how well it works, and why a period app is not contraception. Includes when to get help. *Written and reviewed by the Ruva team · Updated 2026-10-19 · Contraception* ## Key points - Fertility awareness needs training and a plan for your fertile days. - The NHS gives one figure for correct use and another for when instructions aren’t followed exactly. - Period-tracking estimates can’t replace a method you’ve been properly taught. - Fertility awareness doesn’t protect against STIs. Fertility awareness means learning a method and following its rules about when to avoid sex or use a barrier, such as a condom. You can’t rely on a calendar’s estimated fertile window alone as contraception. ## What you learn to observe Each day, you record your body temperature, your vaginal discharge and where you are in your cycle. A specially trained professional teaches you how to use these notes. On days that count as fertile, you avoid sex or use condoms. Some methods use signs of fertility, such as the fluid from your cervix or your body temperature. Others use calendar sums. CDC treats these as different approaches. Ask which method you’re being taught and what information it needs. Ask too what to do if you miss a reading or can’t tell what it means. Learning takes practice. The NHS says it can take 2 to 3 menstrual cycles to learn to use the method properly. During that time, use other contraception or don’t have sex. Ask your teacher how they’ll check that you understand the method before you rely on it. ## How effectiveness varies The NHS says fertility awareness methods are between 91% and 99% effective if you always use them correctly. If the instructions aren’t followed exactly, it gives a figure of 76%. That means 24 in 100 women get pregnant in a year. These figures describe groups of women using the methods. They can’t estimate your chance of pregnancy on any one day. US guidance gives a different range. CDC lists typical-use failure rates of 2-23% across fertility awareness methods and says the rates differ between methods. The US figures count failures, while the NHS figures above describe how well the methods work. Neither can tell you whether one time having sex will lead to pregnancy. Before choosing this method, think about the daily effort and your plan for fertile days. Ask yourself whether avoiding sex or using a barrier on those days suits your life. Talk this through at your teaching appointment. ## Where period apps fit The NHS doesn’t officially recommend apps or fertility-monitoring devices for this. In the US, there is FDA-cleared contraceptive software, and CDC counts it as a fertility awareness method. This software is made for contraception. That doesn’t mean every period-tracking app can be used the same way. Ruva is a diary, and you must never use its estimates as contraception. A date you entered is a record. A fertile window the app works out is only an estimate. For contraception, use the advice for the specific method you’ve been taught. ## When extra advice is needed Irregular periods can make fertility awareness unsuitable. You may need to avoid pregnancy because of a health condition, or a medicine that could harm a baby. If so, the NHS advises asking whether the method suits you. Don’t stop a prescribed medicine without talking to your doctor. CDC notes that changes to periods around the first periods and around perimenopause can make these methods harder to use. Breastfeeding can also make fertility awareness less effective. Using breastfeeding as contraception is called the lactational amenorrhoea method. It has its own rules and is separate from simply tracking your cycle. A fever can make temperature readings hard to read. Some medicines also affect how regular your cycle is or your signs of fertility. If this happens, talk to your practitioner rather than changing the method yourself. Fertility awareness doesn’t protect against STIs, but condoms can lower that risk. ## After sex without reliable contraception Contact a pharmacist or sexual health service today (UK, US and elsewhere) about emergency contraception if you had sex without a barrier on a day you might have been fertile, got the days wrong, or relied on an app’s estimate. Explain what happened and when. The sooner you use emergency contraception, the better it usually works. ## Finding someone to teach you In the UK, book with a GP surgery, sexual health clinic or midwife and ask for someone trained in fertility awareness. In the US and elsewhere, ask your healthcare provider for a practitioner with that training. Say whether you want to avoid pregnancy or are thinking about trying for a baby. Ask what contraception to use while you learn. ## When to get help - **Same day:** Contact a pharmacist or sexual health service today (UK, US and elsewhere) about emergency contraception if you had sex without a barrier on a day you might have been fertile, got the days wrong, or relied on an app’s estimate. Explain what happened and when. - **Book an appointment:** Book with a GP, sexual health clinic or midwife (UK), or your healthcare provider (US and elsewhere), before relying on fertility awareness, especially if your periods are irregular or you take medicines that could affect a pregnancy. ## Where you live Services and advice differ between countries. - **UK:** The NHS recommends learning from a trained practitioner. It does not officially recommend fertility-tracking apps or devices. - **US:** CDC counts FDA-cleared contraceptive software as a fertility awareness method. It reports typical-use failure rates of 2-23% across the different methods. - **Elsewhere:** Elsewhere, find a healthcare professional trained in the method and ask what to use while you’re learning. ## Sources 1. [Natural family planning](https://www.nhs.uk/contraception/methods-of-contraception/natural-family-planning/), NHS 2. [Appendix F: Classifications for Fertility Awareness-Based Methods](https://www.cdc.gov/contraception/hcp/usmec/fertility-awareness-based-methods.html), CDC 3. [Contraception and Birth Control Methods](https://www.cdc.gov/contraception/about/index.html), CDC 4. [Birth Control](https://www.fda.gov/consumers/free-publications-women/birth-control), FDA 5. [Emergency contraception](https://www.who.int/news-room/fact-sheets/detail/emergency-contraception), WHO 6. [Emergency contraception](https://www.nhs.uk/contraception/emergency-contraception/), NHS --- This guide is general information to help you keep and use your own records. It isn’t medical advice. If you’re worried about a symptom, or something changes suddenly, talk to a doctor, nurse or pharmacist.