What Is the Billings Method and How Does It Work?

The Billings Ovulation Method tracks a single biomarker that reveals your fertility status each day: cervical mucus. Developed by Drs John and Evelyn Billings in Melbourne during the 1950s, this method has been validated by research across more than 100 countries and is used by millions of women worldwide.

Unlike methods requiring thermometers, urine tests, or wearable devices, the Billings Method asks you to observe what your body already produces. This simplicity makes it accessible, but proper instruction from a certified teacher is essential for effective use.

What makes the Billings Method different from other fertility awareness methods?

The Billings Method focuses on one observable sign: cervical mucus. Other fertility awareness methods, such as the Symptothermal Method, require tracking multiple biomarkers including basal body temperature, cervical position, and mucus observations.

This single-biomarker focus offers practical advantages. You do not need to wake at the same time each morning to take your temperature. You do not need devices or test strips. You simply observe the sensation and appearance of mucus as you go about your day.

Research published in the journal Human Reproduction found that mucus-only methods like Billings achieve effectiveness rates comparable to multi-biomarker approaches when users receive proper instruction.

How does cervical mucus indicate fertility?

Your cervix produces mucus throughout your cycle. The characteristics of this mucus change based on where you are in your hormonal cycle, providing reliable fertility signals.

Basic Infertile Pattern (BIP): After menstruation, many women experience dryness or an unchanging mucus pattern. This baseline varies between individuals. Some women have continuous mucus as their normal BIP, while others experience complete dryness. Both patterns are normal.

Developing mucus: As oestrogen rises before ovulation, you may notice mucus becoming visible. It often appears cloudy, sticky, or tacky at first.

Fertile mucus: Peak fertility brings clear, stretchy, slippery mucus with a lubricative sensation. This mucus helps sperm survive and travel toward the egg. When you notice this pattern, ovulation is approaching.

Post-ovulatory change: After ovulation, progesterone causes an abrupt change. The fertile sensation disappears, replaced by stickiness, tackiness, or dryness.

What are the four rules of the Billings Method?

The Billings Method uses four rules for avoiding pregnancy. These rules were developed through clinical research spanning decades and have been tested across diverse populations.

Early Day Rules (before ovulation is detected):

1. Avoid intercourse during heavy menstrual bleeding. Heavy bleeding can mask mucus observations.

2. Alternate evenings are available during your Basic Infertile Pattern. This spacing allows any mucus changes to become apparent.

Peak Rule (around ovulation):

3. From the first sign of change from your BIP, avoid intercourse until the fourth day after Peak. This covers your fertile window completely.

Late Day Rule (after ovulation confirmed):

4. From the fourth day after Peak until menstruation, intercourse is available any time. Ovulation has occurred and cannot happen again this cycle.

How effective is the Billings Method?

When used correctly with proper instruction, the Billings Method achieves effectiveness rates comparable to hormonal contraception.

A systematic review published in the Cochrane Database found correct-use effectiveness of 99.5% for mucus-only methods. However, typical-use effectiveness depends heavily on instruction quality.

The World Health Organization multi-country study found typical-use effectiveness of 97% among women who received proper teaching. Without instruction, effectiveness drops significantly.

This gap between correct-use and typical-use rates explains why certification bodies like BOMA and WOOMB emphasise working with trained instructors.

Why is instruction from a certified teacher essential?

The Billings Method appears simple because it tracks only one biomarker. However, learning to identify your personal pattern requires guidance from someone trained to teach the method.

Every woman's Basic Infertile Pattern is unique. Some women have continuous mucus as their baseline. Others experience complete dryness. A certified instructor helps you identify your specific pattern and apply the rules correctly to your situation.

Special circumstances add complexity:

• Breastfeeding suppresses ovulation but can create confusing mucus patterns
• Perimenopause brings irregular cycles and changing baselines
• Coming off hormonal contraception may cause temporary pattern disruption
• Stress, illness, or travel can affect observations

A certified instructor from BOMA UK or WOOMB International provides personalised support through these situations.

How can technology support Billings charting without compromising privacy?

Traditional Billings charting uses paper charts reviewed with an instructor. This approach works well and many women prefer it. Digital tools can add convenience, but most fertility apps create privacy concerns.

When you log observations in a cloud-based app, that data travels to company servers. Someone else gains access to your cycle history, fertile windows, and intimate health patterns. This data can be breached, subpoenaed, or sold.

We built MyBillingsMethod differently. Your observations stay on your Mac. There are no cloud servers storing your fertility data. The app works offline because there is nothing to sync. We cannot see your data because we never receive it.

This is privacy by architecture, not just a privacy policy. Policies can change. Servers can be breached. But if your data never leaves your device, these risks do not apply.

Our on-device AI helps you recognise patterns in your observations without sending data anywhere. You learn to understand your own fertility. The AI supports your learning; it does not make predictions or decisions for you.