Q: Are FABMs the same as the rhythm method / calendar method / “safe days”?

A: Fertility awareness based methods are not the same thing as the rhythm/calendar method (also called “safe days”) although calendar-based methods are considered a sub-class of FABMs. The rhythm method, developed in the 1930s, is based on estimating the fertile time of the menstrual cycle with calculations based on previous cycle lengths. It was a valuable predecessor for the modern FABMs but is not based on observing and charting biomarkers other than menstrual bleeding.

Calendar-based methods work best for those with regular cycles. Because the menstrual cycle is highly susceptible to outside influences and also affected by a person’s general state of health, calculations or an algorithm-based app cannot account for the fluctuations that might take place during any given menstrual cycle and across the reproductive life cycle.

The most reliable FABMs are based on day-to-day observations of bodily signs/biomarkers which allows for accurate and timely identification of the fertile and infertile time.

Q: Can you really avoid pregnancy using an FABM? I’ve heard that users of “safe days” are called “parents”.

A: All fertility awareness based methods have solid scientific evidence about human reproduction behind them. Some methods are more reliable than others in identifying the fertile window but all methods reduce the chances of pregnancy considerably when intercourse is avoided or another method (usually male condom) is used during the fertile window. Rhythm method, often referred to as “safe days” in the Nordic countries, reduces the chances as well but it is not one of the most effective FABMs. The perfect use efficacy for FABMs varies from 95% to well over 99% depending on the method. 

All FABMs, however, are behavioural methods which means that their effectiveness is very much user-dependent and the difference between perfect and typical use pregnancy rates can be wide. People who are committed to avoiding pregnancy altogether are more likely to use these methods successfully than those who are merely looking to space pregnancies or are ambivalent about their pregnancy intentions. A fertility awareness based method might be the best choice for someone not looking to actively achieve a pregnancy but wanting to leave the possibility open, because the methods allow for different levels of risk taking. However, many of the methods are suitable for those looking for a highly effective method of contraception if both partners are willing and able to commit to learning their method of choice with care and using it according to the guidelines. 

Q: Are FABMs only suitable for those with very regular cycles?

A: Some fertility awareness based methods are best suited for those with regular cycles but many can be used by people with irregular cycles as well. Calendar-based methods are either contraindicated (Standard Days Method) or not recommended (rhythm method or algorithm-based apps) for those with very irregular cycles. Temperature-only and double-check symptothermal methods can be used by those with irregular cycles but extended periods of assumed fertility and thus abstinence or using an alternative method for long periods of time will be required in longer cycles. Single-check symptothermal and mucus-only methods that allow the fertile window to be opened and closed more than once during one cycle might be a better option for those with irregular cycles but learning the method and using it properly will likely take a longer time and the efficacy might be somewhat lower (research on using these methods with very irregular cycles is lacking). 

Using a fertility awareness based method can help those with very irregular cycles to keep track of where they are in their cycle and know when to expect the menstrual flow even if the method is not used for birth control. Using a FABM can be very helpful for those experiencing irregular cycles and trying to achieve a pregnancy because timing intercourse (or insemination) correctly can otherwise be very challenging. 

Q: Can FABMs be used when one doesn’t have a cycle?

A: Fertility awareness based methods can be used by female-bodied individuals with intact ovaries during their reproductive years. Some FABMs can be used by amenorrheic individuals (those experiencing a prolonged absence of menstruation). Absence of menstruation means absence of ovulation and thus infertility but because return to fertility and ovulation precedes menstruation, amenorrhea itself mostly cannot guarantee avoidance of pregnancy. Those not ovulating and menstruating cannot use calendar-based or temperature-only methods but might be able to use mucus-only, single-check symptothermal, and symptohormonal methods. Double-check symptothermal methods that have guidelines for postpartum and perimenopause charting are an option for those whose amenorrhea is due to these life stages. When not experiencing a menstrual cycle and using an FABM to avoid pregnancy, potential return to fertility is charted and intercourse avoided or another method used on days indicated as potentially fertile by the method of choice.

Learning to chart when not ovulating/menstruating and becoming confident in identifying potentially fertile times can be challenging and take more time. Charting cervical mucus or urine hormone metabolites when experiencing unexplained amenorrhea (not due to eg. breastfeeding, perimenopause, drugs or surgery) can potentially help one gain more information as to the cause of amenorrhea when working with a practitioner trained to use menstrual cycle charts as a health tool. 

Q: Can FABMs be used while breastfeeding?

A: Some fertility awareness based methods can be used while breastfeeding even if not yet ovulating and menstruating. Once the cycle resumes, any FABM can be used. Those not ovulating and menstruating cannot use calendar-based or temperature-only methods but might be able to use mucus-only, single-check symptothermal, and symptohormonal methods. Double-check symptothermal methods that have guidelines for postpartum charting are an option as well. When not experiencing a menstrual cycle and using a FABM to avoid pregnancy, potential return to fertility is charted and intercourse avoided or another method used on days indicated as potentially fertile by the method of choice.

Using an FABM in this life stage can be challenging but is often easier if using a method already learned before the pregnancy. Different methods have different guidelines for postpartum charting and learning the guidelines with a fertility awareness educator is highly recommended even for those who were successfully using their method before the pregnancy. It is also good to know that efficacy might be somewhat impacted (research on using these methods during breastfeeding amenorrhea is lacking).

Using an FABM during breastfeeding can help track the hormonal changes and return of fertility and thus menstruation even if not using the method for birth control (providing that ovulation-inhibiting hormonal contraceptives are not used).   

 Q: Can FABMs be used by those experiencing perimenopausal changes?

A: Perimenopause means the time “around menopause”, that is, the years leading up to the cessation of menstruation and the year after. The menstrual cycle can change in several ways in the years leading up to menopause. Cycles can get shorter, irregular or longer before they cease altogether.

Because of the higher incidence of early ovulation, calendar-based and temperature-only methods are more likely to fail those over 40 years of age. Cervical mucus tends to lessen as we age so using a mucus-only or a single-check symptothermal method especially when accompanied by irregular ovulation can be more challenging during this life stage. Double-check symptothermal methods with guidelines for perimenopause charting are a good option in this life stage. Working with a fertility awareness educator is highly recommended, even for those using a method successfully before experiencing perimenopause-related changes. A change of method might also be indicated.