Natural family planning

This article is about methods of family planning approved by the Catholic Church. For a more general use of the term, see fertility awareness.

Natural family planning
Background
Birth control type	behavioral
First use	Ancient: calendar, LAM mid-1930s: BBT 1950s: mucus
Failure rates (First six months: LAM Per year: symptoms- and calendar-based)
Perfect use	LAM: 0.5% Symptoms based: 1–3% Calendar based: 5–9%
Typical use	LAM: 2% Symptoms based: 2–25% Calendar based: 25%
Usage
Reversibility	Yes
User reminders	Dependent upon strict user adherence to method
Clinic review	None
Advantages and disadvantages
STD protection	No
Periods	Prediction
Benefits	In accord with Catholic teachings, no drug effects, can aid pregnancy achievement

Natural family planning (NFP) is a term referring to the family planning methods approved by the Roman Catholic Church. In accordance with the Church's requirements for sexual behavior in keeping with its philosophy of the dignity of the human person, NFP excludes the use of other methods of birth control.

Periodic abstinence and the natural infertility caused by breastfeeding are the only methods deemed moral by the Church for avoiding pregnancy. When used to avoid pregnancy, NFP limits sexual intercourse to naturally infertile periods; portions of the menstrual cycle, during pregnancy, and after menopause. Various methods may be used to identify whether a woman is likely to be fertile; this information may be used in attempts to either avoid or achieve pregnancy.

History

Pre-20th century

Possibly the earliest Christian writing about periodic abstinence was by St. Augustine. In the year 388, he wrote, "Is it not you who used to counsel us to observe as much as possible the time when a woman, after her purification, is most likely to conceive, and to abstain from cohabitation at that time...?"^[1] The Manichaeans (the group the early church father St. Augustine wrote of) believed that it was immoral to create any children, thus (by their belief system), trapping souls in mortal bodies. Augustine condemned them for their use of periodic abstinence: "From this it follows that you consider marriage is not to procreate children, but to satiate lust."^[1]

If the Manichaeans had an accurate idea of the fertile portion of the menstrual cycle, such knowledge died with them.^[2] Documented attempts to prevent pregnancy by practicing periodic abstinence do not appear again until the mid-19th century, when various calendar-based methods were developed "by a few secular thinkers."^[3] The Roman Catholic Church's first recorded official statement on periodic abstinence to avoid pregnancy is from 1853, where a ruling of the church's Sacred Penitentiary addressed the topic of periodic abstinence to avoid pregnancy. Distributed to confessors, the ruling stated that couples who had, on their own, begun the practice of periodic abstinence—especially if they had "legitimate reasons"—were not sinning by doing so.^[4]

In 1880, the Sacred Penitentiary reaffirmed the 1853 ruling, and went slightly further. It suggested that, in cases where the couple was already practicing artificial birth control, and could not be dissuaded to cease attempting birth regulation, the confessor might morally teach them of periodic abstinence.^[4]

Early 20th century

In 1905 Theodoor Hendrik van de Velde, a Dutch gynecologist, showed that women only ovulate once per menstrual cycle.^[5] In the 1920s, Kyusaku Ogino, a Japanese gynecologist, and Hermann Knaus, from Austria, working independently, each made the discovery that ovulation occurs about fourteen days before the next menstrual period.^[6] Ogino used his discovery to develop a formula for use in aiding infertile women to time intercourse to achieve pregnancy.

In 1930, John Smulders, a Roman Catholic physician from the Netherlands, used Knaus and Ogino's discoveries to create a method for avoiding pregnancy. Smulders published his work with the Dutch Roman Catholic medical association, and this was the official rhythm method promoted over the next several decades.^[6] While maintaining procreation as the primary function of intercourse, the December 1930 encyclical Casti Connubii by Pope Pius XI gave the highest form of recognition to a secondary—unitive—purpose of sexual intercourse. This encyclical stated that there was no moral stain associated with having marital intercourse at times when "new life cannot be brought forth." Although this referred primarily to conditions such as current pregnancy and menopause, the Sacred Penitentiary in yet another ruling in 1932,^[7] and the majority of Catholic theologians also interpreted it to allow moral use—for couples with "upright motives"—of the newly created rhythm method.^[4][8]:231

In 1932 a Catholic physician published a book titled The Rhythm of Sterility and Fertility in Women describing the method,^[3] and the 1930s also saw the first U.S. Rhythm Clinic (founded by John Rock) to teach the method to Catholic couples.^[9] It was during this decade that Rev. Wilhelm Hillebrand, a Catholic priest in Germany, developed a system for avoiding pregnancy based on basal body temperature.^[10]

Later 20th century to present

^[3] A minority of Catholic theologians continued to doubt the morality of periodic abstinence.^[4] Some historians consider two speeches delivered by Pope Pius XII in 1951^[11] to be the first unequivocal acceptance of periodic abstinence by the Catholic Church.^[3] The 1950s also saw another major advance in fertility awareness knowledge: Dr. John Billings discovered the relationship between cervical mucus and fertility while working for the Melbourne Catholic Family Welfare Bureau. Dr. Billings and several other physicians studied this sign for a number of years, and by the late 1960s had performed clinical trials and begun to set up teaching centers around the world.^[12]

Humanae Vitae, published in 1968 by Pope Paul VI, addressed a pastoral directive to scientists: "It is supremely desirable... that medical science should by the study of natural rhythms succeed in determining a sufficiently secure basis for the chaste limitation of offspring." This is interpreted as favoring the then-new, more reliable symptoms-based fertility awareness methods over the rhythm method. Just a few years later, in 1971, the first organization to teach a symptothermal method (one that used both mucus and temperature observations) was started. Now called Couple to Couple League International, this organization was founded by John and Sheila Kippley, lay Catholics, along with Dr. Konald Prem.^[10] During the following decade, other now-large Catholic organizations were formed: Family of the Americas (1977), teaching the Billings method,^[13] and the Pope Paul VI Institute (1985), teaching a new mucus-only system called the Creighton Model.^[14]

Today, use of the term natural family planning to describe calendar-based methods is considered incorrect by the United States Conference of Catholic Bishops: it considers such methods "inaccurate".^[15] Still, some organizations still consider calendar-based methods to be forms of NFP.^[8]:154 For example, in 1999 the Institute for Reproductive Health at Georgetown University developed the Standard Days Method (SDM), which is more effective than the rhythm method.^[16] SDM is promoted by Georgetown University as a form of natural family planning.^[17]

Prevalence

It is estimated that 2–3% of the world's reproductive age population relies on periodic abstinence to avoid pregnancy.^[18] Breastfeeding is believed to reduce the world's fertility rate by 30–45%.^[8]:145 However, what portion of this population should be considered NFP users is unclear. Some Catholic sources consider couples that violate the religious restrictions associated with natural family planning to not be NFP users.^[8]:13[19]

There is little data on the worldwide use of natural family planning. In Brazil, NFP is the third most popular family planning method.^[20] The "safe period" method of fertility awareness is the most common family planning method used in India, although condoms are used by some.^[21]

Use of NFP in developed countries is low, even among Catholics. While Catholics made up 24% of the U.S. population in 2002,^[22] of reproductive age American women using birth control, only 1.5% were using periodic abstinence.^[23]

Use of NFP is not restricted to Catholic couples. In 2002, Sam and Bethany Torode, then a Protestant Christian couple, published a book advocating NFP use.^[24] (Five years after writing the book, the Torodes retracted their advocacy of pure NFP and also supported barrier methods as moral; the couple also converted from Protestantism to the Eastern Orthodox Church.)^[25]

Not contraception

Some proponents of NFP differentiate it from other forms of birth control by labeling them artificial birth control.^[26][27] Other NFP literature holds that natural family planning is distinct from contraception.^[28][29][30] Proponents justify this classification system by saying that NFP has unique characteristics not shared by any other method of birth regulation except for abstinence. Commonly cited traits are that NFP is "open to life,"^[27][30] and that NFP alters neither the fertility of the woman nor the fecundity of a particular sex act.^[28][29] That NFP can be used to both avoid or achieve pregnancy may also be cited as a distinguishing characteristic.^{[citation needed]} Additionally, NFP differs greatly from contraception because, according to action theory, NFP does not "break" the sexual act (separating the action from its purposes) in the way contraception does.

Methods

There are three main types of NFP: the symptoms-based methods, the calendar-based methods, and the breastfeeding or lactational amenorrhea method. Symptoms-based methods rely on biological signs of fertility, while calendar-based methods estimate the likelihood of fertility based on the length of past menstrual cycles. According to the Couple to Couple League, "the fact that some methods of NFP can be 99% effective in the avoidance of pregnancy seems unknown to most of the general public-including many health care professionals."^[31]

Clinical studies by the Guttmacher Institute, instead, showed a much lower efficacy, with 25.3% of failures in typical use condition.^[32]

Symptoms-based

Main article: Fertility awareness

Some methods of NFP track biological signs of fertility. When used outside of the Catholic concept of NFP, these methods are often referred to simply as fertility awareness-based methods rather than NFP.^[33] The three primary signs of a woman's fertility are her basal body temperature, her cervical mucus, and her cervical position.^[34] Computerized fertility monitors may track basal body temperatures, hormonal levels in urine, changes in electrical resistance of a woman's saliva or a mixture of these symptoms.^[35]

From these symptoms, a woman can learn to assess her fertility without use of a computerized device. Some systems use only cervical mucus to determine fertility. Two well-known mucus-only methods are the Billings ovulation method and the Creighton Model FertilityCare System. If two or more signs are tracked, the method is referred to as a symptothermal method. Two popular symptothermal systems are taught by the Couple to Couple League and the Fertility Awareness Method (FAM) taught by Toni Weschler.^[36] A study completed in Germany in 2007 found that the symptothermal method has a method effectiveness of 99.6%.^[37]

In Canada, the symptothermal method is taught by SERENA Canada which is an inter-denominational organization which has been developing the Symptothermal Method as a part of NFP since 1955. They are also not specifically affiliated with the Roman Catholic Church. It is also taught by Justisse Healthworks for Women, a pro-choice feminist organization that allows and supports women to combine other methods of birth control with their fertility awareness practice.

Calendar-based

Main article: Calendar-based methods

Calendar-based methods determine fertility based on a record of the length of previous menstrual cycles. They include the Rhythm Method and the Standard Days Method. The Standard Days method was developed and proven by the researchers at the Institute for Reproductive Health of Georgetown University. CycleBeads, unaffiliated with religious teachings, is a visual tool based on the Standard Days method. According to the Institute of Reproductive Health, when used as birth control, CB has a 95% effectiveness rating. iCycleBeads is the first iPhone app based on a natural family method, Standard Days. Women can plan or prevent pregnancy naturally via their iPhone or Apple brand device.^[38]

Lactational amenorrhea

Main article: Lactational amenorrhea method

The lactational amenorrhea method (LAM) is a method of avoiding pregnancy based on the natural postpartum infertility that occurs when a woman is amenorrheic and fully breastfeeding. The rules of the method help a woman identify and possibly lengthen her infertile period. A strict version of LAM is known as ecological breastfeeding.^[39]

Theology

Main article: Christian views on contraception#Roman Catholicism

Official Catholic

Catholic doctrine holds that God created sexual intercourse to be both unitive and procreative.^[40] The Catholic Church teaches that an act which deliberately attempts to divorce the unitive and procreative meaning of the marital act is opposed to God's plan for life and love in the order of creation. "[A]ny action which either before, at the moment of, or after sexual intercourse, is specifically intended to prevent procreation—whether as an end or as a means" is opposed to this order and is therefore forbidden according to orthodox Catholic teaching. Thus, artificial birth control methods are forbidden, as are acts intended to end in orgasm outside the context of intercourse (e.g. masturbation or oral sex that is not part of foreplay).^[41] At the same time, not having sex at all (abstinence) is considered morally acceptable.^[40]

Engaging in marital relations at an infertile time in a woman's life (such as pregnancy or post-menopause) is also considered acceptable, since the infertile condition is considered to be created by God, rather than as an act by the couple.^[42] Similarly, under Catholic theology, it may be morally acceptable to abstain during the fertile part of the woman's menstrual cycle.^[40] Increasing the postpartum infertile period through particular breastfeeding practices — the lactational amenorrhea method — is also considered a natural and morally unobjectionable way to space a family's children.^[43]

The Catholic Church acknowledges a potential benefit of spacing children^[40] and use of NFP for this reason is tolerated. Humanae Vitae cites "physical, economic, psychological and social conditions" as possibly compelling reasons to avoid pregnancy.^[44] Couples are warned, however, against using NFP for selfish, immoral, or insincere reasons.^[40] A few Catholic theologians argue that couples with several children may morally choose to avoid pregnancy, even if their circumstances (emotional, physical, and economic) would allow for more children.^[45] More commonly, Catholic sources extol the benefits children bring to their parents, their siblings, and society in general, and encourage couples to have as many children as their circumstances make practical.^{[46][47][48][49]}

Dissident and other opposing

See also: Christian views on contraception#Natural Family Planning only or "artificial" methods too?

Some Catholics have indicated significant disagreement with the Church's stance on contraception.^[50] The Canadian Conference of Catholic Bishops issued what many interpreted as a dissenting document, the Winnipeg Statement. In it, the bishops recognized that many Catholics found it "either extremely difficult or even impossible to make their own all elements of this doctrine" (that of Humanae Vitae).^[51] Additionally, they reasserted the Catholic principle of primacy of conscience,^[51] a principle that they said should be properly interpreted, since they insisted that "a Catholic Christian is not free to form his conscience without consideration of the teaching of the magisterium, in the particular instance exercised by the Holy Father in an encyclical letter".^[52] Catholics for a Free Choice claimed in 1998 that 96% of U.S. Catholic women had used contraceptives at some point in their lives and that 72% of Catholics believed that one could be a good Catholic without obeying the Church's teaching on birth control.^[53] According to a nationwide poll of 2,242 U.S. adults surveyed online in September 2005 by Harris Interactive, 90% of Catholics supported the use of birth control/contraceptives.^[54] Use of natural family planning methods among United States Catholics purportedly is low, although the number cannot be known with certainty. In 2002, 24% of the U.S. population identified as Catholic.^[22] But of sexually active Americans avoiding pregnancy, only 1.5% were using NFP.^[23]

Much criticism of NFP stems from the Church's stance of NFP as the only allowable form of birth control. In 2009, Pope Benedict XVI asserted that handing out condoms is not the solution to combating AIDS and actually makes the problem worse.^[55] Some senior Catholic authorities, such as Belgian Cardinal Emeritus Godfried Danneels, believe the Catholic Church should support condoms used to prevent serious diseases such as AIDS, because non-use is tantamount to murder.^[56] In 2003 BBC's Panorama claimed that the Vatican is intentionally spreading lies that HIV virus can pass through the membrane of the condom.^[57]

Family planning proponent Stephen D. Mumford has argued that the primary motivation behind the Church's continued opposition to contraceptive use is the Church's fear of losing papal authority if the pope were to contradict the dogma of papal infallibility.^[58] Mumford gives as an example the citation made by August Bernhard Hasler of a comment by Pope John Paul II prior to his papacy:

If it should be declared that contraception is not evil in itself, then we should have to concede frankly that the Holy Spirit had been on the side of the Protestant churches in 1930 (when the encyclical Casti Connubii was promulgated), in 1951 (Pius XII's address to the midwives), and in 1958 (the address delivered before the Society of Hematologists in the year the pope died). It should likewise have to be admitted that for a half century the Spirit failed to protect Pius XI, Pius XII, and a large part of the Catholic hierarchy from a very serious error. This would mean that the leaders of the Church, acting with extreme imprudence, had condemned thousands of innocent human acts, forbidding, under pain of eternal damnation, a practice which would now be sanctioned. The fact can neither be denied nor ignored that these same acts would now be declared licit on the grounds of principles cited by the Protestants, which popes and bishops have either condemned or at least not approved.^[59]

Theological opposition has additionally come from Protestant Christianity. John Piper's Desiring God ministry states of NFP, "There is no reason to conclude that natural family planning is appropriate but that 'artificial' means are not."^[60] Sam and Bethany Torode, former advocates of NFP-only, have redacted their position to include barrier methods and explain their current theology this way:

We also see honest congruity with the language of the body by saying "no" to conception with our bodies (via barrier methods or sensual massage) when our minds and hearts are also saying "no" to conception. We don’t believe this angers God, nor that it leads to the slippery slope of relativism or divorce. We strongly disagree with the idea that this is a mortal sin.... it’s a theological attack on women to always require that abstinence during the time of the wife’s peak sexual desire (ovulation) for the entire duration of her fertile life, except for the handful of times when she conceives.^[25]

Catholics such as Charles Curran have also criticized the stance of Vitae on artificial birth control.^[61]

See also

• Catholic teachings on sexual morality
• New feminism
• Theology of the Body
• Couple to Couple League

References

• "Humanae Vitae". Encyclical of Pope Paul VI. The Holy See. July 25, 1968. http://www.vatican.va/holy_father/paul_vi/encyclicals/documents/hf_p-vi_enc_25071968_humanae-vitae_en.html. Retrieved 2006-06-15. 
• Patrick Coffin (2010). Sex au naturel: what it is and why it's good for your marriage. Steubenville, Ohio: Emmaus Road. ISBN 679605023. OCLC 679605023. http://books.google.com/books?id=rKEAWJaQJAMC. , an informative, concise introduction to Natural Family Planning

Notes

1. ^ ^{a b} Saint, Bishop of Hippo Augustine; Philip Schaff (Editor) (1887). A Select Library of the Nicene and Post-Nicene Fathers of the Christian Church, Volume IV. Grand Rapids, MI: WM. B. Eerdmans Publishing Co.. pp. On the Morals of the Manichæans, Chapter 18. 
2. ^ Green, Shirley (1972). The Curious History of Contraception. New York: St. Martin's Press. pp. 138–43. ISBN 0852230168. 
3. ^ ^{a b c d} Yalom, Marilyn (2001). A History of the Wife (First ed.). New York: HarperCollins. pp. 297–8, 307. ISBN 0-06-019338-7. 
4. ^ ^{a b c d} Pivarunas, Mark A (February 18, 2002). "On the Question of Natural Family Planning". cmri.org. Congregatio Mariae Reginae Immaculatae. http://www.cmri.org/03-nfp.html. Retrieved 2008-04-27. 
5. ^ "A Brief History of Fertility Charting". FertilityFriend.com. http://www.fertilityfriend.com/Faqs/A_brief_history_of_fertility_charting.html. Retrieved 2006-06-18. 
6. ^ ^{a b} Singer, Katie (2004). The Garden of Fertility. New York: Avery, a member of Penguin Group (USA). pp. 226–7. ISBN 1-58333-182-4. 
7. ^ Harrison, Brian W (January 2003). "Is Natural Family Planning a 'Heresy'?". Living Tradition. Roman Theological Forum. http://www.rtforum.org/lt/lt103.html. Retrieved 2008-04-27. 
8. ^ ^{a b c d} Kippley, Sheila; Kippley, John F. (1996). The art of natural family planning (Fourth ed.). Cincinnati, OH: Couple to Couple League International. ISBN 0-926412-13-2. 
9. ^ Gladwell, Malcolm (2000-03-10). "John Rock's Error". The New Yorker. 
10. ^ ^{a b} Hays, Charlotte (December 2001). "Solving the Puzzle of Natural Family Planning". Crisis Magazine. http://www.holyspiritinteractive.net/features/prolife/article_05.asp. Retrieved 2009-07-31. 
11. ^ Moral Questions Affecting Married Life: Addresses given October 29, 1951 to the Italian Catholic Union of midwives and November 26, 1951 to the National Congress of the Family Front and the Association of Large Families, National Catholic Welfare Conference, Washington, DC.
12. ^ Billings, John (March 2002). "THE QUEST — leading to the discovery of the Billings Ovulation Method". Bulletin of Ovulation Method Research and Reference Centre of Australia 29 (1): 18–28. http://www.woomb.org/omrrca/bulletin/vol29/no1/thequest.shtml. Retrieved 2007-03-18. 
13. ^ "About us". Family of the Americas. 2006. http://www.familyplanning.net/main.php?parent_id=1&id_area=1. Retrieved 2007-03-18. 
14. ^ "About the Institute". Pope Paul VI Institute. 2006. http://www.popepaulvi.com/about.htm. Retrieved 2007-03-18. ^{[dead link]}
15. ^ "Basic Information on Natural Family Planning". United States Conference of Catholic Bishops. July 2007. http://www.usccb.org/prolife/issues/nfp/information.shtml. 
16. ^ Arévalo M, Jennings V, Sinai I (2002). "Efficacy of a new method of family planning: the Standard Days Method." (PDF). Contraception 65 (5): 333–8. doi:10.1016/S0010-7824(02)00288-3. PMID 12057784. http://pdf.dec.org/pdf_docs/PNACQ416.pdf. 
17. ^ "Research-to-Practice -- Standard Days Method". Georgetown University. 2004. http://www.irh.org/RTP-SDM.htm. Retrieved 2009-07-31. 
18. ^ Che Y, Cleland J, Ali M (2004). "Periodic abstinence in developing countries: an assessment of failure rates and consequences". Contraception 69 (1): 15–21. doi:10.1016/j.contraception.2003.08.006. PMID 14720614. 
19. ^ "Question #8". FREQUENTLY ASKED QUESTIONS. Serena Canada. 2006. Archived from the original on 2004-10-20. http://web.archive.org/web/20041020125539/http://www.serena.ca/eng/faq.html#q8. Retrieved 2007-03-19. 
20. ^ Keller S (1996). "Traditional beliefs part of people's lives". Network 17 (1): 10–1. PMID 12320441. 
21. ^ Urmil Dosajh, Ishita Ghosh, and Rebecka Lundgren (September 2005) (PDF). Feasibility of Incorporating the Standard Days Method into CASP Family Planning Services in Urban Slums of India. The Institute for Reproductive Health, Georgetown University. pp. vi. http://pdf.usaid.gov/pdf_docs/PNADG768.pdf. Retrieved 2008-02-18. 
22. ^ ^{a b} "Largest Religious Groups in the United States of America". Adherents.com. 2005. http://www.adherents.com/rel_USA.html. Retrieved 2007-03-19. 
23. ^ ^{a b} Chandra, A; Martinez GM, Mosher WD, Abma JC, Jones J. (2005). "Fertility, Family Planning, and Reproductive Health of U.S. Women: Data From the 2002 National Survey of Family Growth" (PDF). Vital Health Stat (National Center for Health Statistics) 23 (25). http://www.cdc.gov/nchs/data/series/sr_23/sr23_025.pdf. Retrieved 2007-05-20.  See Table 56.
24. ^ Sam Torode, Bethany Torode, J. Budziszewski (March 2002). Open Embrace: A Protestant Couple Rethinks Contraception. Grand Rapids, Michigan: Wm. B. Eerdmans Publishing Company. ISBN 0-8028-3973-8. 
25. ^ ^{a b} Torode, Bethany (2006). "An Update From Bethany". http://www.openembrace.com/. Retrieved 2007-03-13. 
26. ^ Saunders, William (1995-10-26). "The Practice of Natural Family Planning". The Arlington Catholic Herald. Eternal Word Television Network. http://www.ewtn.com/library/ANSWERS/PRACTNFP.HTM. Retrieved 2009-08-05. 
27. ^ ^{a b} "Birth Control and NFP: What's the Difference?". Priests for Life. 1999. http://priestsforlife.org/articles/nfpdifferences.html. Retrieved 2009-08-05. 
28. ^ ^{a b} "NFP vs. Contraception". Couple to Couple League. 2005. http://www.ccli.org/nfp/contraception/NFPvsContraception.php. Retrieved 2009-08-05. 
29. ^ ^{a b} McManaman, Doug (2004). "The Moral Difference Between Contraception and Natural Family Planning". LifeIssues.net. http://www.lifeissues.net/writers/mcm/mcm_04moraldifference.html. Retrieved 2009-08-05. 
30. ^ ^{a b} Habiger, Matthew (2007). "Is NFP "Catholic" contraception?". NFP Outreach. http://www.nfpoutreach.org/Q&A/CATHOLIC-%20CONTRACEPTION.htm. Retrieved 2009-08-05. 
31. ^ Couple to Couple League http://ccli.org/nfp/basics/effectiveness-p01.php
32. ^ http://www.guttmacher.org/pubs/fb_contr_use.html
33. ^ Weschler, Toni (2002). Taking Charge of Your Fertility (Revised ed.). New York: HarperCollins. p. 5. ISBN 0-06-093764-5. 
34. ^ Weschler, p.52
35. ^ Basal body temperatures: FAQs on Lady-Comp temperature readings
    Hormone levels in urine: Clearblue Easy Fertility Monitor home page
    Sympto-thermal observations (BBT plus LH or Cervical Mucus): cyclotest sympto-thermal device website
    Changes in electrical resistance of saliva: Ovacue website
36. ^ Unlike the organizations associated with other popular observational systems, Toni Weschler has no connection to the Roman Catholic Church.
37. ^ P. Frank-Hermann, J.Heil, C. Gnoth, et al. “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,”Human Reproduction, 2007, 1-10
38. ^ Medical Eligibility Criteria for Contraceptive Use:Fertility awareness-based methods. Third edition. World Health Organization. 2004. http://www.who.int/reproductive-health/publications/mec/fab.html. Retrieved 2008-04-29. 
39. ^ "Ecological Breastfeeding" (Internet Archive). Couple to Couple League International. Internet Archive. 2006. Archived from the original on 2006-01-11. http://web.archive.org/web/20060111170320/ccli.org/nfp/ebf/summary.php. Retrieved 2008-06-04. 
40. ^ ^{a b c d e} "#2363-2370". Catechism of the Catholic Church, Second Edition. United States Catholic Conference. 2000. pp. Article 6: The Sixth Commandment. Archived from the original on 2006-04-24. http://web.archive.org/web/20060424162544/http://www.usccb.org/catechism/text/pt3sect2chpt2art6.htm#2363. Retrieved 2006-06-15. 
41. ^ Christopher West (2000). Good News about Sex and Marriage: Answers to Your Honest Questions about Catholic Teaching. Servant Publications. pp. 88–91. ISBN 1569552142. 
42. ^ "Casti Connubii". Encyclical of Pope Pius XI. United States Catholic Conference. 1930. pp. Section 59. http://www.vatican.va/holy_father/pius_xi/encyclicals/documents/hf_p-xi_enc_31121930_casti-connubii_en.html. Retrieved 2006-06-15. 
43. ^ "NFP - Two basic forms". Couple to Couple League. http://www.ccli.org/nfp. Retrieved 2006-06-24. 
44. ^ Humane Vitae (1968) Section I.10
45. ^ Thomas Storck (2006). NFP: A Defense and an Explanation. Archived from the original on 2007-05-06. http://web.archive.org/web/20070506214018/http://www.ignatius.com/magazines/hprweb/storck.htm. Retrieved 2007-04-27. , which cites:

    Ford, John C.; Gerald Kelly (1963). Contemporary Moral Theology: Vol.2 (II), Marriage Questions. Westminster, Md: Newman Press. pp. 422–423. 

46. ^ Humanae Vitae (1968) Section I.9
47. ^ "The Blessings of Children". One More Soul. Archived from the original on 2006-06-14. http://web.archive.org/web/20060614194727/http://www.omsoul.com/the-blessings-of-children.php. Retrieved 2006-06-24. 
48. ^ "In Praise of Big Families". CatholicExchange.com. http://www.catholicexchange.com/vm/index.asp?art_id=32777. Retrieved 2006-06-24. ^{[dead link]}
49. ^ "Principles of the Couple to Couple League". Couple to Couple League International. http://ccli.org/learn/promote/principles.php. Retrieved 2006-06-24. 
50. ^ Roderick Hindery (1990). "The Evolution of Freedom as Catholicity in Catholic Ethics". In Ed. Starr, Bradley E.; Gard, Donald; Benjamin J. Hubbard. Anxiety, guilt, and freedom: religious studies perspectives: essays in honor of Donald Gard. Washington, D.C: University Press of America. ISBN 0-8191-7683-4.  - A summary and restatement of the debate
51. ^ ^{a b} "Canadian Bishops' Statement on the Encyclical "Humanae Vitae"". Archived from the original on 2006-08-29. http://web.archive.org/web/20060829044505/http://www.catholic-legate.com/articles/winnipeg.html. Retrieved 2006-10-02. 
52. ^ Canadian Conference of Catholic Bishops Plenary Assembly, 18 April 1969, Statement on Family Life and Related Matters
53. ^ Catholics for a Choice (1998). "A Matter of Conscience: Catholics on Contraception" (PDF). Catholics for a Choice. http://www.catholicsforchoice.org/topics/prevention/documents/1998amatterofconsciece.pdf. Retrieved 2006-10-01. 
54. ^ Harris Interactive (2005). "The Harris Poll #78". Harris Interactive. http://www.harrisinteractive.com/harris_poll/index.asp?PID=608. Retrieved 2006-10-01. 
55. ^ Condoms 'not the answer to AIDS': Pope
56. ^ Alsan, Marcella (April 2006). "The Church & AIDS in Africa: Condoms & the Culture of Life". Commonweal: a Review of Religion, Politics, and Culture 133 (8). http://www.aids.net.au/us-catholic-20060421.htm. Retrieved 2006-11-28. 
57. ^ "Sex and the Holy City". Panorama. BBC News. 12 October 2003. http://news.bbc.co.uk/nol/shared/spl/hi/programmes/panorama/transcripts/sexandtheholycity.txt. 
58. ^ "WHY THE POPE CAN'T CHANGE THE CHURCH'S POSITION ON BIRTH CONTROL: IMPLICATIONS FOR AMERICANS, A presentation by Stephen D. Mumford DrPH [1]
59. ^ Hasler, August Bernhard (1981). How the Pope Became Infallible: Pius IX and the Politics of Persuasion. Doubleday. ISBN 0385158513. 
60. ^ Desiring God Staff (2006). "Does the Bible permit birth control?". Questions and Answers. Desiring God. http://www.desiringgod.org/ResourceLibrary/AskPastorJohn/ByTopic/45/1440_Does_the_Bible_permit_birth_control/. Retrieved 2006-10-27. 
61. ^ Curran, Charles E. (2006). Loyal Dissent: Memoir of a Catholic Theologian (Moral Traditions). Washington, D.C: Georgetown University Press. ISBN 1-58901-087-6. 

External links

• Natural Family Planning at the Open Directory Project

Press

• New Life for Family Planning, Michael P. Harris, Time, September 19, 1988
• The Orgasmatron Finally Shows Up: High Tech Rhythm New York Observer, June 27, 2004

NFP information

• Catholic Answers NFP Q&A
• Online Safe period Calculator
• Billings Ovulation Method
• Creighton Model System
• The Couple to Couple League
• Lady Calendar
• Lady Comp
• SERENA Canada
• Northwest Family Services
• Pope John Paul II on Distorted Views of Marriage & Family Sermon examining NFP in light of tradition.
• [2] Clarifying the church's teaching on contraception and NFP with Fr. Chad Ripperger, FSSP
• Comprehensive website which provides women with free fertility charting tools, techniques, advice and instructions.