I DEFINING BASIC TERMS
Efficacy is a complex term that is widely misunderstood and misrepresented. It requires translation, nuance, and knowledge about basic terms so users can make informed decisions about contraception.
All birth control methods have two kinds of effectiveness rates: theoretical/ method effectiveness and actual/user effectiveness.
Method effectiveness refers to the degree of efficacy reached under ideal conditions when used correctly and consistently by the individual/couple. All contraceptive methods have a theoretical effectiveness of 98% or higher. Method effectiveness is another way of stating “perfect use”.
User effectiveness refers to the degree of efficacy reached under typical, real-life conditions, taking into account human nature, which is often less than perfect, and even irrational. User effectiveness is another way of stating ‘imperfect use.”
One way to grasp the practical significance of perfect vs imperfect use is by dividing all methods into four basic sub-types; each type of method requires a different mindset, priority, value and skill set. There are methods that require:
- no behavioral effort on the part of user e.g. IUDs and implants
- low level of behavioral effort, e.g. hormonal methods which require remembering to take a pill every day or replacing a vaginal ring every month
- medium level of effort, e.g. barrier methods like diaphragms and condoms as well as spermicides and withdrawal
- high level of effort, e.g. FAM/STMs and other FABMs which require are 100% user-controlled
As a rule, hormonal methods and IUD’s have higher efficacy whereas most non-hormonal methods generally have lower efficacy. Why? Because they require more skill, diligence, and long-term effort. As a result, there can be a 10-20% gap between perfect use and typical use. For example, hormonal methods have a nearly 100% theoretical effectiveness rate (when used perfectly- correctly and consistently) but actual effectiveness is closer to 90%, because they are not used perfectly (most surveys reveal that at least once a month, users forget to take their pills at the right time).
In theory, all methods are inherently reliable, but in reality, they can be less than reliable because not all people are consistently diligent and responsible when implementing them. As a rate, theoretical effectiveness refers to perfect users -those who follow the rules every time and don’t take risks or chances. Actual effectiveness includes those who are perfect users and those who are not.
So here is a list of things you will want to know:
II APPLYING BASIC TERMS
- A researcher cannot measure “perfect use” because s/he is not present during any sexual act in order to determine whether or not a couple is using a given method in a correct and consistent way. Because of this methodological pitfall, researchers rely on another measure: failure rate. They will ask the question not in terms of perfect use but in terms of typical use or user failure. In other words, how many people experience an unintended pregnancy while using a given method of contraception during a certain period of time under study?
- Birth control effectiveness rates/statistics published by reproductive/ health organizations (e.g. CDC, WHO, Contraceptive Technology, Planned Parenthood) are actually “estimates” based on a mixture of data collected from clinical trials and large population surveys like the National Survey of Family Growth (NSFG). They are not true, absolute numbers derived from exact circumstances nor are they numbers that personally apply to you. Researchers use various mathematical formulas to calculate these estimates, because this is the next best way to determine relative efficacy.
- An effectiveness rate deemed high in one trial, among one ethnic/socio-economic/age group in one specific place/country may be lower in another group and place. The efficacy rate from one study is not necessarily applicable when applied to people in another place. For example- measuring the efficacy of condom use among adult men in Japan (a country and culture which takes condom use very seriously and strictly) will yield much lower efficacy rates in a population of teenagers in the U.S.). The efficacy of birth control pills among adolescents is naturally lower than for older women. These factors enable us to understand that the “technical” and inherent factors which determine effectiveness are not the bottom-line; culture, religious beliefs, age, behavior, values and norms have a direct effect on contraceptive efficacy statistics.
III HOW EFFECTIVE IS FAM (AND OTHER STMs)?
This depends on how “strict” a couple decides to be. FAM, as taught by Poriutivit (a variation of the book, TCOYF), is one of a dozen schools of natural methods referred to as “Sympto-Thermal Methods” or STM’s. STMs are methods which rely on observing and interpreting at least two (out of three) primary fertility signs- basal temperature (thermal) and cervical secretions (sign-symptom of ovulation) – which confirm when the fertile window closes. Poriutivit, as some other STM’s, takes into account other signs which confirm when the fertile window opens, such as previous cycle length, internal secretion checks, the presence of any secretion or the presence of a fertile secretion. Some schools encourage checking cervical position (optional biomarker).
STM’s are taught in more than a dozen “variations on a theme.” STM’s fit under the larger umbrella term of FABM’s (Fertility Awareness- Based Methods). All FABMs are “natural,” but not all of them meet the criteria of STMs (observational vs calculation methods). All the STM variations are based on the same science, but lean on different research studies and ideological approaches. They have the same goal: giving users tools for identifying the fertile days of the cycle and teaching the rules that “protect” the user from unintended pregnancy. Some STM programs are funded and promoted by the Catholic Church around the world and encourage abstinence-only during the fertile days and some STM’s are promoted by secular groups who encourage couples to choose whether or not to use barrier and other methods during the fertile days.
STMs are very effective among perfect users. Among imperfect users, they can be very “unforgiving.” On average, typical users (self- taught) can experience a 10-20% failure rate during the first year of use. Among perfect users (taught and followed with a certified teacher), first-year failure rates are lower, only 5-10%. For couples who only have intercourse after ovulation or who correctly use two methods simultaneously during the fertile days, user effectiveness can approach 100% (re the latter, we do not yet have high-quality studies to confirm this).
Unlike hormonal and IUD methods, STM’s like FAM have a relatively wider range of effectiveness because:
- they are more difficult to research (perfect use with natural methods means more than remembering to swallow a pill every day) and
- they involve time, standardized learning, follow-up and supervision by a qualified teacher.
- they require communication skills, partner cooperation, high motivation, on-going decision-making and discipline.
Unlike conventional methods of contraception, STM’s (including Poriutivit) divide the menstrual cycle into 3 phases of fertile and infertile days:
Phase 1: from first day of menstrual bleeding until fertile window opens (small risk)
Phase 2: all the days of the fertile window (typically 3-5 on average) (high risk)
Phase 3: from time fertile window closes (based on two signs) to the next period (typically 10-14 days on average) (no risk)
Since each phase confers a different risk, effective use of FAM requires that:
- Users always use one barrier/back-up method (during learning phase) during Phase I and two barrier/back-up methods during the fertile days in Phase 2.
- Users knows how to identify the fertile days/window of the menstrual cycle and then adapt their sexual behavior to the method rules as taught.
- Users properly chart BBT & secretion changes for confirming the opening and closing of the fertile window. Without a clear, defined window, there is no method.
- Users acquire experience, skill and confidence with other back-up methods (condoms, withdrawal, diaphragms, spermicides) before they start to use them in “real time.” Since no back-up method is 100% effective when used alone, we combine two methods simultaneously to increase effectiveness, e.g. a spermicide used together with a condom; withdrawal with the sponge, or a diaphragms with gel. This requirement is best understood by the common example: If and when a condom breaks on a fertile day, the result can be a 100% pregnancy. Therefore we need another method to increase efficacy.
- Couples remember that FAM is not a “stand-alone” method. When the method was first developed, it assumed that couples would abstain for nearly half of the days of the cycle. If a couple chooses to use other methods during fertile of potentially fertile days, then the effectiveness of these other methods supersedes the effectiveness of FAM/STMs (which are typically based on abstinence-only for one-third to one-half of the cycle).
- Couple understands the difference between method failure and user failure.
IV WHEN FAM IS “UNFORGIVING”
Unintended pregnancies are almost always the result of user failure, which occurs when users: chart inconsistently, have trouble identifying the fertile window, err in interpreting their charts, ignore or incorrectly use method rules, engage in risk-taking behavior during the pre-fertile and fertile phase (unprotected or partially protected sex). Furthermore, a user can become complacent over time, by assuming she knows what is/is going to happen, based on past cycles/charts. These “errors” can be kept to a minimum when students maintain contact with their instructors, particularly during the learning phase (typically 3 months or cycles). This is particularly important when a new learner is in hormonal transition e.g. coming off hormones, post miscarriage or abortion, breastfeeding, has irregular cycles or in peri-menopause.
V FAM EFFECTIVENESS
- A literature review of some FABMs and STMs shows a range of effectiveness.
|Type of Method||Theoretical effectiveness||Actual effectiveness|
|Basal Body Temperature||98%||90-97%|
|Ovulation (Billings) (CS)||98%||63-97%|
|Rhythm and Calendar||98%||76-84%|
2. The range of actual effectiveness tells us a few important things:
It provides a clue as to how subjectively easy or difficult a method will be to use. For example, the Ovulation (Billings) Method may require more experience and expertise than the Temperature Method alone because interpreting changes in secretions is more complex than interpreting changes in basal temperature.
- Some STMs have rules which basically prohibit intercourse during the pre-ovulation phase of the cycle and/or during the fertile days- which means there are less absolute days of “potential risk” which translates into a higher effectiveness rate.
- If a couple uses other methods, incorrectly or inconsistently, on these days, then the potential risk can translate into lower efficacy.
- Most STM’s teach that any secretion (even dry, sticky, acidic) observed after menstrual bleeding and staining is potentially fertile. Poriutivit does not subscribe to this idea because in the same way we recognize infertile secretions after ovulation and during long periods of breastfeeding, we can recognize them beforehand as well. After charting 4-6 cycles, most women can know their infertile days before ovulation.
On the other hand, taking advantage of sexual freedom on these days requires a very high level of diligence and responsibility
VI The bottom line
Personal, statistical, actual effectiveness for FAM (and other STM’s) is highly dependent on the characteristics of the user/s, i.e.
- Knowing and understanding how the method works
- motivation to prevent pregnancy + satisfaction with the method
- correct and consistent use
- skill, experience, confidence
- partner support/cooperation and social support/acceptance
- using and receiving follow-up from a qualified teacher
- the hormonal health and overall health of the user
- frequency of intercourse and age of user
- There is no perfect method or method that is 100% (only abstinence).
- A number (statistic) does not protect you against unintended pregnancy; correct and consistent use of a method protects you.
- Technology can fail people just as people can fail technology.
- Contraceptives are imperfect and can fail the most diligent users.
- Using two methods together dramatically lowers the risk of accidental pregnancy.
- FAM works best when it syncs with personal values, priorities and lifestyle.
- FAM works when chosen for the right reason: it’s the best method for someone’s values, lifestyle, health and sexual relationship. Choosing FAM as the “default” method (because all other methods are rejected or unacceptable) is a different, “weaker” choice as it may not confer high efficacy over time.
- FAM is not for everyone. It works best when there’s a genuine desire to know your body and take full responsibility for your sexual health. It requires a commitment to learn properly and having a supportive partner. When chosen for the right reasons and implemented in a serious and stable relationship, FAM can be a highly effective and safe method of contraception.
Rates calculated from studies reviewed in:
- Contraceptive Technology, Robert Hatcher, et al.18th Revised Edition, 2004, pp 221-252.
- Contraceptive Efficacy, J. Trussell. Global Library Women’s Medicine (GLOWN), 2014
- Contraceptive Failure in the United States: Estimates from the 2006–2010 National Survey of Family Growth, A. Sundaram et al. 2017