Scientific Basis

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 PhaseEstrogen is produced within the ovaries by the follicles, which are stimulated by follicular stimulating hormoneEstrogen 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 quicklyEstrogen also softens and opens the cervix and moves it higher in the vaginal canal.

2. OvulationLuteinizing 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 PhaseProgesterone 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?