Learning a new fertility awareness method (FAM), while a valuable skill, can be a big commitment. Often, it involves finding an instructor, taking a class, and tracking multiple cycles with an instructor’s help before becoming fully capable of successfully charting independently. However, there are a few methods that take a simpler approach. The TwoDay Method, for example, is a FAM known for its simplicity. With an easy-to-teach approach and no required materials, you could start using the TwoDay Method right away, but this simplicity comes with both pros and cons.
What is the TwoDay Method?
The TwoDay Method is a fertility awareness method developed by the Institute for Reproductive Health (IRH) at Georgetown University. This method focuses on the presence or absence of cervical mucus (that is, it’s a mucus-only method, along the lines of the Billings or Creighton methods, but with fewer rules). Its main use is to avoid pregnancy by helping a woman to determine whether or not she is fertile on a particular day with some simple criteria.
How does it work?
To use the TwoDay Method, a woman would check for cervical secretions a couple of times each day. The method isn’t strict about how this is done; noticing fluid on underwear, toilet paper, or with a finger at the vaginal opening all count as noticing secretions for that day. Rather than classifying different kinds of cervical mucus, like with other FAMs, the fluid can be any color, type, or consistency. However, users are instructed not to count blood as a secretion and to wait until menstrual flow stops before checking for secretions.
If secretions were noticed today OR the day before, the user should consider herself fertile and avoid sex that day (to avoid pregnancy). The method just requires that the woman check twice during the day.
But at what point does she make the judgment call that there were no secretions that day? Presumably she would decide at the end of the day. If there were no secretions that day and none the day before (hence, “TwoDay” Method), then a woman would consider herself to not be fertile and could have intercourse that evening.
Benefits of the TwoDay Method
A big benefit of the TwoDay Method is its simplicity. It can be explained easily and quickly, especially compared to FAMs that classify different types of cervical mucus or use multiple biomarkers. With cervical mucus as the only biomarker, users do not need any tools to take basal body temperature, as with the Sympto-Thermal method, or test hormones, as with the Marquette Method. While there are tracking card templates women can use, as long as a woman remembers whether or not there were secretions the day before, she can use this method without any materials.
This simplicity and no-cost maintenance is very intentional. The efficacy study for this method took place in Guatemala, Peru, and the Philippines where women have less access to medical services than in more economically developed countries [1]. In the original research article explaining the development of the TwoDay Method, it was described as being an effective alternative to more complicated methods in areas with low literacy rates or where methods with longer time requirements for instruction would be less feasible [2].
Drawbacks of the TwoDay Method
All cervical mucus is considered fertile
One drawback of the TwoDay Method is that all cervical secretions are considered fertile. While this may be the case for some women, other women experience cervical fluid secretions every day or nearly every day of the cycle (for example, women with PCOS may experience this). In this case, a woman would need to look for when mucus changes to become clear, stretchy, and slippery when looking for fertile days. Granted, for these women, the TwoDay Method could still be used to prevent pregnancy, but every day would be considered an abstinence day and the method may lose some appeal.
Typical use pregnancy effectiveness is lower than with other FAMs
In the efficacy study which took place in Guatemala, Peru, and the Philippines, researchers reported a pregnancy rate of 3.5 (this means 3.5 unintended pregnancies per year per 100 women), or about 96.5% effective at preventing pregnancy [1]. Notably, the pregnancy rate for women who use the TwoDay Method with a “backup” method on fertile days (such as condoms), was nearly double: 6.5, or about 93.5% effective at preventing pregnancy. (More on how condoms may increase the likelihood of unintended pregnancy when paired with an FAM is here.)
Perfect use
However, it’s important to note that the efficacy study reflected the “correct use” or “perfect use” pregnancy prevention rate of the TwoDay Method. At a perfect use rate of 96.5%, the TwoDay Method is slightly less effective than the perfect use rate of condoms (98%) or the birth control Pill (99%), and less than more conservative FAMs with stricter rules, such as Creighton, Billings, Sympto-Thermal, and Marquette, which boast perfect use effectiveness rates ranging from 98-99%, depending on the method.
Typical use
The “typical use” rate of unintended pregnancy for the TwoDay method was 14 (or, 86% effective at preventing pregnancy), which is considerably worse than more conservative FAMs with stricter rules, such as Creighton, Billings, Sympto-Thermal, and Marquette, which boast typical use effectiveness rates ranging from 90-98%, depending on the method. It’s also slightly worse than the typical use effectiveness of the Pill (about 93%), but roughly on par with the typical use effectiveness of condoms (about 86-87%).
Why the lower rates?
For ease of use, the TwoDay Method considers all secretions as potentially fertile, but this may lead to many “precautionary” abstinence days (especially in women with long mucus patches or continuous mucus, as with PCOS). The high number of abstinence days, especially for women with continuous mucus, may contribute to a low typical-use rate.
The TwoDay Method also presumes infertility (meaning “go” days for sex for couples trying to avoid pregnancy) during the woman’s period. From the Institute for Reproductive Health’s TwoDay Method FAQ, “The TwoDay Method considers days with menstruation as non-fertile, since the probability of pregnancy is very low on these days. The days that pass between menstruation and ovulation are more than enough for sperm to lose their potential to fertilize the egg (the viable lifespan of the sperm is up to five days).” However, for women with shorter-than-average cycles, it is possible that some days of menstruation are potentially fertile, and that menstrual blood could be masking the presence of cervical mucus.
The method doesn’t help users monitor hormonal or overall health
This method is also less appealing if you are not sexually active or if you are looking to use a FAM for more than pregnancy prevention. Without education on identifying a peak day (when ovulation likely occurred), users will not have the tools to predict their periods or identify charting patterns that may indicate something is wrong hormonally.
Takeaways: to use or not to use the TwoDay Method?
The TwoDay Method is useful for what it was designed for: a simple, easy-to-learn FAM for reasonably reliable pregnancy prevention, especially when a woman adheres closely to the rules of the method. For women who want more than pregnancy prevention from their fertility awareness method, the TwoDay Method might be a good stepping stone to other methods. It can help women get into the habit of checking cervical mucus a couple times each day, and considering which days may be fertile. These good habits can be translated into another method that also uses cervical mucus as a biomarker. If someone likes the TwoDay Method overall and seeks a similar experience with a little more structure and higher pregnancy prevention effectiveness, the Billings Method may be a good fit for them!
