Scientific Basis of Fertility Awareness Methods
Methods of natural family planning that depend upon fertility awareness, including the Justisse Method, have evolved from scientifically validated principles relating to menstrual cycle events that enable a woman to differentiate her fertile and infertile periods during any given cycle.
Think of the various methods of fertility awareness as brands. These brands include: Fertility Awareness Method, Natural Family Planning, Billings Ovulation Method, Couple-to-Couple League, Creighton Method, Serena, Sympto-Thermal Method and Justisse Method. These brands differ from each other in various and important ways - eg. charting method, fertility signs observed, rules to avoid or to achieve pregnancy, ideological and/or religious foundation - but the effectiveness of each and every one of them depends on the same scientific principles.
Why does Fertility Awareness work?
The effectiveness of fertility awareness to help couples avoid or achieve pregnancy or monitor gynecological and reproductive health, relies on the fact that all women can be taught to observe, chart and interpret the three primary signs of fertility: cervical mucus secretions, basal body temperature and cervical position.
Fertility signs are influenced by the primary hormones of the menstrual cycle. Each cycle unfolds in three distinct phases. Women who use hormonal birth control including oral contraceptives or Depo-Provera will not experience these cyclical changes.
The Three Phases of the Menstrual Cycle:
1. Pre-ovulation or Follicular Phase: Estrogen is produced within the ovaries by the follicles, which are stimulated by follicular stimulating hormone. Estrogen cools body temperature for the healthy production of eggs and stimulates a changing, developing pattern of cervical mucus production that typically culminates with secretions the consistency and color of egg white. Sometimes these secretions are not seen but felt as a lubricative (slippery) sensation at the vulva. This fertile quality cervical mucus can keep sperm alive for up to 5 days. When this fertile quality mucus is not present, sperm die quickly. Estrogen also softens and opens the cervix and moves it higher in the vaginal canal.
2. Ovulation: Luteinizing Hormone is the pituitary hormone that surges when one follicle reaches maturity to prompt the release of the egg from the ovary. The egg lives for 12 to 24 hours. If a second egg is released, it is released within 24 hours of the first egg.
3. Post-ovulation or Luteal Phase: Progesterone is produced by the corpus luteum (the egg-releasing follicle) after ovulation. It prevents the release of all other eggs that cycle. Progesterone causes the uterine lining to thicken and sustain itself until the corpus luteum disintegrates, about two weeks after ovulation, or a pregnancy results. Progesterone also causes the three primary fertility signs to change. Basal body temperature rises, thecervix closes, lowers and returns to “firm”, and cervical mucus secretions dry up. The luteal phase, once the egg dies, is infertile. It typically lasts 12 to 16 days, but rarely varies by more than a day or two within individual women.
In healthy, the pre-ovulation phase can vary in length due to stress or illness, while the post-ovulation phase remains constant. Women who chart their fertility signs can accurately predict the onset of their next periods.
Regardless of cycle length (25 to 36 days is considered normal), cycle regularity, relationship status, or reproductive age - from adolescence through to menopause - women can apply these scientific principles to determine their fertile days during each cycle and to monitor their gynecological health.
Whether or not women use fertility awareness to prevent or achieve pregnancy, the information gleaned from charting can benefit their health and wellness. Charting cycle events can help diagnose many gynecological conditions including minor infertility problems.
What is the effectiveness rate of fertility awareness methods of birth control?
Certain fertility awareness based methods (FABMs) may be considered 'generic' in that they have adopted systems and techniques from evidence-based methods developed by institutes (mostly Catholic NFP based) who have provided funding for research and development. Most generic methods are secular adaptations of NFP methods. There are many FABMs, some more sophisticated and effective than others.
Peragallo Urrutia, Rachel, MD, MS; Polis, Chelsea B., PhD; Jensen, Elizabeth T., PhD; Greene, Margaret E., PhD; Kennedy, Emily, MA; Stanford, Joseph B., MD, MSPH. Obstetrics & Gynecology: August 06, 2018: Prospective studies evaluating the effectiveness of specific fertility awareness–based methods to avoid pregnancy are of low to moderate quality; effectiveness estimates vary between and among methods.
The effectiveness of a fertility awareness based method to avoid pregnancy in relation to a couple’s sexual behaviour during the fertile time: a prospective longitudinal study
Fertility awareness-based methods of family planning: A review of effectiveness for avoiding pregnancy using SORT
According to a comprehensive study undertaken by the World Health Organization reported in the early 1980's and referenced in The Canadian Consensus Conference on Contraception published in 1998 by the Society of Obstetricians and Gynecologists of Canada, this is what is known:
1. Failure of these methods may be attributed to improper teaching and understanding of the method, and not practising abstinence during the fertile times, or conception occurring due to mathematical calculation sof the "safe" days of the cycle that may or may not correlate with real symptoms of fertility (e.g.rhythm method, calendar method, cycle beads, standard days method).
2. 95% of women are able to learn the sympto-thermal method of natural family planning, meaning a method that incorporates observations of cervical mucus and basal body temperatures (BBT).
3. Perfect use can result in pregnancy rates of less that 5% in couples using the sympto-thermal method.
4. In a large study, a success rate of 99.6% was achieved for couples that only had intercourse on those days, both pre-ovulatory and post-ovulatory, determined by the ovulation method (based on observation, charting and interpretation of cervical mucus secretions alone) to be infertile
It is important to note that the effectiveness rate for perfect use of the ovulation method rivals the effectiveness rate of hormonal birth control methods. This study was undertaken using the ovulation method as taught within a Catholic context, meaning there was no accommodation for the use of barrier methods during the fertile period.
What is perfect use for the Justisse Method?
Perfect use of the Justisse Method of Fertility Management would mean that a woman and her partner strictly observe the rules for avoiding pregnancy set out by the method.
Perfect use also requires that the intention not to become pregnant over rides any doubt about fertility or any consideration to take a risk with an act of unprotected intercourse during a potentially fertile day.
The Justisse Method supports all ways of achieving maximum effectiveness including abstaining from intercourse, alternative forms of sexual expression or the use of barrier methods during the fertile period or on days where doubt of fertility exists. If barrier methods are used during the fertile period, effectiveness rates for these methods - both for typical and perfect use - apply.
The Justisse Method also supports the use of emergency contraception should an act of unprotected intercourse, after the fact, suggest the risk of pregnancy.
Perfect users of the Justisse Method can expect to achieve the effectiveness rate determined by the WHO The Justisse Method can be used as a form of natural birth control.