March 2019

Over 1,000 smartphone applications are currently available to help people track their menstrual cycles.[1] Most are not appropriate for pregnancy prevention,[2] although the millions of people who have downloaded them do not necessarily understand this.[3] Thus, providers should be prepared to guide their patients in identifying and selecting which apps provide accurate information and are appropriate for their particular needs, advise Contraceptive Technology authors Victoria Jennings and Chelsea Polis.[4]

Some apps facilitate use of an existing FABM (Fertility Awareness Based Method, such as a symptothermal method, the Billings Ovulation Method, or the Standard Days method) by providing a digital platform that serves as an alternative to traditional paper and pencil charts or other tools used to track fertility signs. In order to determine which days are fertile or non-fertile, the person using the app is primarily responsible for interpreting the information they enter into these apps, but those who choose an existing FABM app often find it a convenient tool.

Another category of smartphone apps requires input of information about fertility signs but uses a predictive algorithm embedded within the app itself to determine the fertile time—meaning that the user is not primarily responsible for determining which days are fertile or non-fertile.

One app, Natural Cycles, involves temperature monitoring, with the user entering her basal body temperature into the app daily. Users also enter information about menses and, as an option, urinary hormones. The app stores and analyzes this information over time and provides the user with an assessment of her fertility status. A study found a perfect-use annual probability of pregnancy of approximately 1% and an upper limit (i.e., when participants with unknown pregnancy status were considered pregnant) typical-use probability of 9.8%.[5]^,[6] The app has been certified in the European Union to be legally sold and used for contraception.

Another app, Dynamic Optimal Timing (Dot) is based on an algorithm developed from a statistical analysis linking cycle length, timing of ovulation, and variable fecundability of the sperm and ovum to identify fertility status.[7] Theoretical efficacy based on this analysis, though not on actual use, is estimated at 1% to 3%. A prospective efficacy study to assess perfect and typical use has been registered and is underway.[8]

Neither of two mini-computers  with predictive algorithms (LadyComp or Daysy) have been assessed through standard prospective effectiveness studies (though some manufacturers do make unsubstantiated claims about effectiveness).

Studies suggest that many people seeking family planning services would be interested in an FABM if it were explained to them appropriately.[9] Fertility awareness-based methods appeal to women who do not wish to use (or cannot use) hormones or devices and are willing to accept a relatively higher contraceptive failure rate.

What do you say to patients who ask about natural family planning? Be aware that the effectiveness rates you quote may be lower than what FABM actually provides. More than 80% of Fertility Awareness-Based methods (FABM) use in recent NSFG surveys is self-reported use of “rhythm.” So these “lumped” estimates of effectiveness may not apply to individual FABMs. Moreover, FABM user instructions—as well as effectiveness—can be enhanced by smartphone apps based upon predictive, embedded algorithms.

Certain conditions that increase the likelihood of irregular cycles may make FABMs more difficult to use, and patients with these conditions require more extensive counseling and follow-up:

• Recent childbirth
• Current breastfeeding
• Recent menarche
• Anovulatory cycling as with PCOS or obesity-related infrequent cycles
• Recent discontinuation of hormonal contraceptive methods
• Approaching menopause

FABMs are also not recommended for persons who are unable to abstain or use other contraceptive methods during the fertile days, for personal, partner, or cultural reasons.

Some couples, providers, and program managers worry that using an FABM will hamper a couple’s sexual life, making the method less acceptable and leading to discontinuation of use. Analysis of intercourse patterns of users of the Standard Days Method and of the TwoDay Method show that people who use these methods have intercourse almost as frequently as do those who use other methods (5.6 and 5.5 coital acts per month, respectively). The pattern differs, however, as the couples who use these two FABMs tend to have sex more frequently during the infertile days before and after the fertile window and avoid sex during their fertile days.[10]

Because unintended pregnancies among couples who use FABMs usually result from having intercourse at the beginning or end of the fertile time, concerns have been raised about the risk of birth defects or poor pregnancy outcomes due to aged ovum or sperm. Research has shown that no such increased risks exist.[11]^,[12] An exception is that, in one prospective study, women with a history of spontaneous abortion had a greater chance of having another spontaneous abortion when conception occurred very early or late in the fertile time (23% of women with a previous spontaneous abortion compared with 10% to 15% of women who had not experienced a previous spontaneous abortion).¹⁰ Providers should reassure any concerned patients that FABMs do not pose a threat to the health of mothers and their children.

A study of about 1,000 births showed no association between the timing of conception and the sex ratio at birth.[13] These results do not substantiate claims that couples can select the sex of their child by timing intercourse.

[1] Moglia ML, Nguyen HV, Chyjek K, Chen KT, Castano PM. Evaluation of smartphone menstrual cycle tracking applications using an adapted APPLICATIONS scoring systems. Obstet Gynecol 2016 Jun;127:1153–1160.

[2] Duane M, Contreras A, Jensen ET, White A. The performance of fertility awareness-based method apps marketed to avoid pregnancy. J Am Board Fam Med 2016;29:508–511.

[3] Simmons RG, Jennings VH, Haile L. Fertility apps: what do women want & need? Presentation at: United States Agency for International Development on App Classification; January 26 2017; Washington, DC.

[4] Jennings V, Polis C. Fertility awareness-based method. In: Hatcher RA, Nelson AL, Trussell J, Cwiak C, Cason P, Policar MS, Edelman A, Aiken ARA, Marrazzo J, Kowal D, eds. Contraceptive technology. 21st ed. New York, NY: Ayer Company Publishers, Inc., 2018.

[5] Berglund SE, Gemzell DK, Sellberg JA, Scherwitzl R. Fertility awareness-based mobile application for contraception. Eur J Contracept Reprod Health Care 2016 Jun;21:234–241.

[6] Berglund Scherwitzl E, Lundberg O, Kopp Kallner H, Trussell J, Scherwitzl R. Perfect-use and typical-use Pearl Index of a contraceptive mobile app. Contraception 2017;96:420–425

[7] Li D, Heyer L, Jennings VH, Smith CA, Dunson DB. Personalised estimation of a woman’s most fertile days. Eur J Contracept Reprod Health Care 2016;21:323–328.

[8] Simmons R, Shattuck D, Jennings V. Assessing the efficacy of an app-based method of family planning: the Dot Study protocol. JMITResearch Protocol, January 2017; 6(10)e5.

[9] Leonard CJ, Chavira W, Coonrod DV, Hart KW, Bay RC. Survey of attitudes regarding natural family planning in an urban Hispanic population. Contraception 2006; 74:313–331.

[10] Stanford JB, Thurman PB, Lemaire JC. Physicians’ knowledge and practices regarding natural family planning. Obstet Gynecol 1999;94:672–678.

[11] Gray RH, Simpson JL, Kambic RT, Queenan JT, Mena P, Perez A, Barbato M. Timing of conception and the risk of spontaneous abortion among pregnancies occurring during use of natural family planning. Am J Obstet Gynecol 1995;172:1567–1572.

[12] Simpson JL, Gray R, Perez A, et al. Fertilization involving aging gametes, major birth defects and Down’s syndrome. Lancet 2002; 359:1670–1671.

[13] Gray RH, Simpson JL, Bitto AC, Queenan JT, Chuanjun L. Sex ratio associated in timing of insemination and length of the follicular phase in planned and unplanned pregnancies during use of NFP. Hum Reprod 1998;13:1397–1400.