Fertility awareness-based methods of cycle tracking—or natural family planning—are all about tracking your menstrual cycle to determine the days that you can get pregnant. It’s tricky and, to do it, you’ll need to pay very close attention to your body and its patterns.
Most people don’t use FAMs (or most other forms of birth control) perfectly, and so the effectiveness rate (i.e. what we tend to see in practice) for FAMs is estimated to be lower. How much lower, though, is up for debate. Different FAMs probably have different effectiveness rates, but few studies are looking at each FAM type (ex. Standard Days or TwoDay methods) to know how well the results are generalisable.
Furthermore, many factors can affect the effectiveness ratings, and there is variability among FAM effectiveness estimates. These include research factors, a person’s menstrual cycle and the accuracy of measurements made by a FAM user.
The Rhythm Method
This is the oldest FAM and is calendar-based. A person should track their menstrual cycles for at least six months before using this method. After having tracked multiple cycles, a person should use both their longest and shortest cycle to determine when they are most likely to be fertile and should avoid sex or use a second form of contraception.
If your cycles aren’t regular and between 26 and 32 days, this is probably not a good method for you. There is no current estimate for how well the rhythm method works.
The Standard Days Method
The Standard Days method follows a standard rule of what days during the menstrual cycle are the most fertile. If your cycle is between 26 days and 32 days long, the Standard Days method considers days 8–19 to be the most fertile. To prevent pregnancy, you should avoid having intercourse or use a barrier method of birth control on these days. To promote pregnancy, you should try to have intercourse between day 8 and day 19, either every day or every other day. The Standard Days method works best if your cycles are regular and are consistently between 26 days and 32 days long.
Five out of 100 people will get pregnant per year if they use this method perfectly, and this method is currently considered a modern contraceptive by the World Health Organisation.
The Cervical Mucus Method
The cervical mucus method involves recognising changes in the mucus produced by the cervix and in how the mucus looks and feels. Just before ovulation, the amount of mucus made by the cervix noticeably increases, and the mucus becomes thin and slippery. Just after ovulation, the amount of mucus decreases, and it becomes thicker and less noticeable. To prevent pregnancy, you should avoid sexual intercourse or use a barrier method of birth control from the time you first notice any cervical mucus. To promote pregnancy, you should have intercourse every day or every other day when the thin and slippery cervical mucus is present.
When using methods that rely on cervical mucus, be aware of any changes in your health or daily routine that could make reading the signs of ovulation difficult. Medications, feminine hygiene products, douching, sexual intercourse, breastfeeding, or having a pelvic exam in which lubrication is used all can change how the cervical mucus appears.
The TwoDay Method
The TwoDay method is a variation of the cervical mucous method. With the TwoDay method, you check your cervical mucus at least twice a day and then ask yourself two questions:
- Did I notice any secretions today?
- Did I notice any secretions yesterday?
If you noticed cervical mucus today or yesterday, you most likely are fertile. To prevent pregnancy, you should avoid sexual intercourse or use a barrier method of birth control. To promote pregnancy, you should have sexual intercourse every day or every other day when you notice secretions. If you did not notice any cervical mucus today and yesterday (2 dry days in a row), pregnancy is less likely.
Four out of 100 people will get pregnant per year if they use this method perfectly.
The Billings Ovulation Method
Similar to the TwoDay method, the Billings Ovulation method uses cervical mucus to estimate the fertile period. People record descriptions of their cervical mucus onto a chart and follow a set of rules as to when they can have sex.
Three out of 100 people will get pregnant per year if they use this method perfectly.
The Basal Body Temperature Method
The BBT is your body’s temperature when you are fully at rest. In most women, the body’s normal temperature increases slightly during ovulation (0.5–1°F) and remains high until the end of the menstrual cycle. The most fertile days are the 2–3 days before this increase in temperature. To monitor your BBT, take your temperature every morning after waking up, before any activity, getting out of bed, or having anything to eat or drink. Record these temperatures daily.
BBT by itself is not a good way to prevent or promote pregnancy. It shows only when ovulation has already occurred, not when it is going to occur. Also, keep in mind that if you have a fever (for example, if you have an ongoing medical condition or if you get sick with the flu), the BBT method may not be reliable.
The Sensiplan Method
Sensiplan (sometimes just called the Sympto-Thermal method; see below)—this method uses cervical mucus and BBT readings to determine the fertile window in each individual cycle.
Fewer than one out of 100 people will get pregnant per year if they use this method perfectly.
The Sympto-Thermal Method
The Sympto-Thermal method is a combination of methods. The two most commonly used are the BBT method and the cervical mucus method. This method combines BBT and cervical mucus tracking with the use of an electronic hormonal fertility monitor. The monitor detects hormones in urine to confirm fertile days. It can be purchased online or at a pharmacy. Other methods or signs can be used, such as the Standard Days Method, as a double-check to identify when the fertile time begins and ends.
Fertility tracking via mobile app
These are relatively new tools that aren’t methods in themselves, but typically use calendar estimates and BBT, and sometimes other symptom inputs, results from luteinizing hormone tests etc. According to recently published research on one such app, one out of 100 people will get pregnant per year if they use this method perfectly; however, these estimates are based on studies with a significant amount of missing data, which may affect this estimate.
My favourite apps to use for tracking are Fertility Friend, Period Tracker, and Flo. Fertility Friend seems to be the most accurate and also allows you to access your information on a computer as well as on the app. Period Tracker allows me to manipulate my ovulation date to test out different theories, and Flo has these amazing health insights that pop up in the app, PLUS it has full-length blog articles that match each one on the website.