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I metodi di riconoscimento della fertilità (in inglese fertility awareness) sono quei metodi che aiutano le coppie ad identificare i periodi infecondi e potenzialmente fecondi del ciclo mestruale. Durante il periodo fecondo e dipendentemente dai propri desideri una coppia può scegliere di praticare sesso per aumentare le probabilità di concepimento oppure può astenersi dal sesso non protetto per evitare una gravidanza indesiderata.
I metodi contraccettivi naturali (in inglese natural family planning) consistono nell'astinenza durante il periodo fecondo; non è considerato "naturale" l'uso di contraccettivi meccanici o farmacologici ed atti che consistano nell'eiaculazione all'esterno della vagina.

Metodi e caratteristiche

Esistono vari metodi per riconoscere i periodi fecondi:

  • Temperatura Basale (BBT), or temperature-only method.
  • Cervical Mucus-only methods. (Cervical mucus is sometimes referred to as cervical fluid.) This includes the Billings Ovulation Method and the Creighton Model. An easier to teach, albeit less effective variation is the Two-Day Method.
  • Sympto-thermo Method - this method combines observations of BBT, cervical mucus, and sometimes cervical position.
  • Though not technically FA, based on the same scientific principles is the Calendar Method. A sub-type of the Calendar Method is the Standard Days Method, which can be used by women who always have cycles between 26 and 32 days. CycleBeads are a device that helps a woman correctly practice the Standard Days Method.
  • Women who are breastfeeding a child and wish to avoid pregnancy may be able to practice the Lactational Amenorrhea Method (LAM), or a stricter version known as Ecological Breastfeeding. These methods are not FA, but because they also do not involve devices or chemicals, they are often presented alongside FA.

FA è il solo metodo id pianificazione familiare che:

  • non può avere effetti collaterali. (Some FA methods encourage internal observation of the cervix or cervical mucus - the insertion of fingers into the vagina for these observations might change the vaginal environment.)
  • can be free, depending on whether or not the couple chooses to use photocopied charts, a basal thermometer, special calendars, special computer software, or other paraphernalia.
  • non utilizza farmaci o agenti chimici e può non utilizzare dispositivi meccanici.
  • can be practiced in accord with moral beliefs of Catholics and adherents of various other religious sects.
  • can be used both to avoid pregnancy and to conceive a child. (In addition to enabling couples to time intercourse correctly, many problems that cause infertility can be diagnosed through FA charts. This can assist womens’ doctors in determining which treatments are needed.)

FA can be used by all women throughout their reproductive life, regardless of whether or not a woman is having regular cycles, is approaching menopause, or is breastfeeding.

Methods of NFP include methods which track indicators of fertility (eg. Sympto-Thermal, Billings, Creighton), methods which make statistical estimates as to when a woman is fertile (eg. Rhythm, Standard Days Method), and methods which help identify and/or encourage breastfeeding infertility.

The Calendar Method, also known as the Rhythm Method or the Knaus-Ogino Method (named after Hermann Knaus and Kyusaku Ogino), relies solely on counting days in order to estimate the onset of a woman's fertile period. This is NOT fertility awareness, though it is based on the same scientific principles. Because of its lower accuracy, many FA teachers consider calendar rhythm to have been obsolete for at least 20 years.

Contraccezione

Il riconoscimento della fertilità combinato con FA can be combined with other forms of birth control, such as condoms. Many couples will use a "back-up" method during the fertile phase, instead of abstaining from intercourse. Couples seeking maximum effectiveness might use their "back-up" method during the infertile phase, and abstain from intercourse during the fertile phase.

Avoiding pregnancy by use of FA requires abstinance from sexual intercourse for at least 8-10 days each cycle. Achieving the highest effectiveness rates can require even more abstinance, though it is rare for couples to need to abstain for more than two weeks. Despite these periods of required abstinence, studies have indicated little or no difference in frequency of intercourse between couples using fertility awareness and those using oral contraceptives. (Couples avoiding intercourse during the fertile phase of the cycles are thus more sexually active during the infertile phases of the cycle.)

Efficacia dei metodi contraccettivi in generale

The effectiveness of FA, as of artificial forms of contraception, can be assessed two ways: method effectiveness and user effectiveness. The method effectiveness is the proportion of couples correctly using the method for a year who do not get pregnant in that year. User effectiveness is the proportion of couples who sometimes use the method incorrectly, and do not get pregnant in that year. Statistics on typical effectiveness (i.e. effectiveness for all couples, regardless of whether they used the method correctly or incorrectly) is generally not available.

For all forms of contraception, user effectiveness is lower than method effectiveness, due to several factors:

  • mistakes on the part of those providing instructions on how to use the method
  • mistakes on the part of the method's users
  • conscious user non-compliance with method.
For instance, someone using oral forms of hormonal birth control might be given incorrect information by a health care provider as to the frequency of intake, or by mistake not take the pill one day, or simply not bother to go to the pharmacy on time to renew the prescription.

Efficacia del riconoscimento della fertilità

I maggiori tassi di efficacia del riconoscimento della fertilità usato come contraccettivo si riscontrano nelle coppie che ricevono istruzioni da parte di un istruttore esperto. L'autoapprendimento con la lettura di uno dei libri sull'argomento funziona per alcune coppie ma si riscrontra un maggiore tasso di fallimento. Se l'intenzione è quella di evitare la gravidanza in ogni caso documentarsi soltanto con materiale online non è raccomandato. Esistono comunque numerosi forum in cui le donne possono aiutarsi ed incoraggiarsi a vicenda e porre o rispondere a domande.

Studi medici hanno mostrato che alcune forme di FA sono efficaci al 99% quando usati correttamente ed accuratamente, raggiungendo un efficacia pari ai contraccettivi orali Ecochard, R.; Pinguet, F.; Ecochard, I.; De Gouvello, R.; Guy, M.; and Huy, F. (1998) "Analysis of natural family planning failures. In 7007 cycles of use", Fertilite Contraception Sexualite 26(4):291-6Hilgers T.W. and Stanford J.B. (1998) "Creighton Model NaProEducation Technology for avoiding pregnancy. Use effectiveness", Journal of Reproductive Medicine 43(6):495-502.

Dati ricavati da Contraceptive Technology James Trussell et al. (2000) "Contraceptive effectiveness rates", Contraceptive Technology — 18th Edition, New York: Ardent Media. On-press.:

  • Post-ovulation methods (i.e. abstaining from intercourse from menstruation until after BBTs have indicated ovulation) have a method failure rate of 1% per year.
  • The symptothermo method has a method failure rate of 2% per year.
  • The cervical mucus-only methods have a method failure rate of 3% per year.
  • Calendar rhythm has a method failure rate of 9% per year.
  • The Standard Days Method has a method failure rate of 5% per year.
  • The Lactational Amenorrhea Method has a method failure rate of 2% in the first six months of use.

Research from the Couple to Couple League International has shown that ecological breastfeeding (a stricter form of LAM) has a method failure rate of 1% in the first six monthsKathy I. Kennedy, Roberto Rivera, and Alan S. McNeilly, "Consensus statement on the use of breastfeeding as a family planning method," Contraception 39:5 (May 1989), and 6% before the first post-partum menstruation. (For women practicing ecological breastfeeding, average onset of menstruation is at 14 months post-partum. For individual women, onset of menstruation varies widely, with anything from 2 months to 48 months post-partum considered normal.)

For all methods cited above, user effectiveness is significantly lower than method effectiveness - user failure rates near 25% per year are commonly cited.

The most common reason for the lower user effectiveness is not mistakes on the part of instructors or users, but conscious user non-compliance Howard, M.P. and Stanford, J.B. (1999) "Pregnancy probabilities during use of the Creighton Model Fertility Care System", Archives of Family Medicine 8(5):391-402Anonymous (1999) "European multicenter study of natural family planning (1989-1995): efficacy and drop-out", Advances in Contraception 15(1):69-83, i.e., the couple knowing that the woman is likely to be fertile at the time, but engaging in sexual intercourse nonetheless. An FA advocate might argue that some of these cases simply constitute a couple's deciding that they are, after all, willing to accept a child as a consequence of intercourse, and hence these cases might not count as failures of FA, but simply as a decision not to use FA.

Several studies have found that the Billings Ovulation Method has over a 99% method effectiveness rate. User effectiveness has been as high as 99%Evaluation of the Effectiveness of a Natural Fertility Regulation Programme in China: Shao-Zhen Qian, et al. Reproduction and Contraception (English edition), in press 2000..

In one study, a Creighton Model achieved 99.5% method effectiveness and a 96.8% user effectiveness. In another study, a Creighton Model had 17% of users getting pregnant, with a vast majority of these getting pregnant due to lack of correct use, so that only 0.14% of the actual users experienced a perfect-use pregnancy.

Research conducted by Ecochard, et al. (1998) found that:

  • FA users can achieve a 98.9% effectiveness rate under ideal conditions.
  • FA users who break one or more rules will average 93.5% effectiveness rate.

By comparison, the Guttmacher Institute reports a user effectiveness rate of 92.0% for "the pill"Alan Guttmacher Institute, "Facts in Brief, First Year Contraceptive Failure Rates" (http://www.agi-usa.org/pubs/fb_contr_use.html). Retrieved May 10, 2005.

Basi scientifiche

L'ovocita muore se non è fertilizzato entro 24 ore dall'ovulazione. L'ovulazione può essere rilevata attraverso cambiamenti nella temperatura basale, nella composizione del muco della cervice o nella sua posizione. Trascorsa l'ovulazione il concepimento non è più possibile per il resto del ciclo.

Gli spermatozoi sono in grado di fertilizzare un ovocita per un periodo fino a cinque giorni successivo all'eiuaculazione, se non è presente muco cervicale l'ambiente acido all'interno della vagina risulta solitamente in un molto minore tempo di vita degli spermi.

Intercourse that occurs more than five days before ovulation will not result in pregnancy. Intercourse that occurs in the presence of cervical mucus, and/or right before the temperature shift is most likely to result in pregnancy.

Molte donne possono individuare l'ovulazione con cinque o più giorni di anticipo, ottenendo sufficiente tempo per evitare o pianificare una gravidanza.

Observational Methods

This description is an overview only. Couples wishing to use Fertility Awareness to avoid or encourage pregnancy should seek instruction from an experienced teacher.

The three primary fertility signs are basal body temperature (BBT), cervical mucus, and cervical position. A woman practicing fertility awareness may choose to observe one sign, two signs, or, all three.

Basal body temperature is a person’s temperature taken when they first wake up in the morning (or after their longest sleep period of the day). In women, ovulation will trigger a rise in BBT between 0.3 and 0.9C (0.5 and 1.6°F) that lasts approximately until the next menstruation. Sixty percent of the time, ovulation happens the day before the temperature rise. The other forty percent of the time, ovulation may happen a few days in either direction.

The appearance of cervical mucus and vulvar sensation are generally described together as two ways of observing the same sign. Cervical mucus is produced by the cervix, the muscle that separates the uterus from the vaginal canal. Cervical mucus is a heterogeneous mixture of different types of mucus, several of which have specialized functions. Some of its functions are similar to those of semen - cervical mucus promotes sperm life by decreasing the acidity of the vagina and providing nurishment to the sperm. One type of mucus has a structure that helps guide sperm into the cervix and then the uterus. The production of fertile cervical mucus is caused by the same hormone (estrogen) that prepares a woman’s body for ovulation. By observing her cervical mucus, and paying attention to the sensation as it passes the vulva, a woman can detect when her body is gearing up for ovulation, and also when ovulation has passed. When ovulation occurs, estrogen production drops slightly and progesterone starts to rise. The rise in progesterone causes a distinct change in the quantity and quality of mucus observed at the vulvaOvarian Activity and Fertility . Each of the methods of fertility awareness observes and interprets this occurrence differently, and uses different rules to determine the onset of fertility and post-ovulatory infertility.

The cervix changes position in response to the same hormones that cause cervical mucus to be produced and to dry up. When a woman is in an infertile phase of her cycle, the cervix will be low in the vaginal canal; it will feel firm to the touch (like the tip of a person’s nose); and, the os – the opening in the cervix – will be relatively small, or ‘closed’. As a woman becomes more fertile, the cervix will rise higher in the vaginal canal; it will become softer to the touch (more like a person’s lips); and the os will become more open. After ovulation has occurred, the cervix will revert to its infertile position.

There are other techniques for detecting ovulation. Unlike the three primary signs described above, these other methods are not considered sufficiently accurate to avoid pregnancy. They are often used by couples seeking to conceive.

Ovulation Predictor Kits (OPKs) can detect imminent ovulation from the concentration of lutenizing hormone (LH) in a woman’s urine. A positive OPK is usually followed by ovulation within 12-36 hours.

Saliva microscopes, when correctly used, can detect ferning structures in the saliva that precede ovulation. Ferning is usually detected beginning three days before ovulation, and continuing until ovulation has occurred.

Fertility monitors are available under various brand names. These monitors use a combination of the calendar method, OPKs, and sometimes computerized interpretation of BBTs. Though the manufacturers claim high effectiveness rates for avoiding pregnancy, independent studies show failure rates comparable to the calendar method.

Many women experience secondary fertility signs that correlate loosely with ovulation. Examples include breast tenderness and middleschmertz (ovulation pains).

Utenti

NFP is the only contraceptive method permitted by the Roman Catholic Church. Worldwide, many Catholics use NFP in obedience to church teaching. The practice of NFP among Catholics in developed countries, however, is rather low. In 2002, 24% of the U.S. was Catholic.Largest Religious Groups in the USA. Accessed November 13, 2005. Of sexually active Americans avoiding pregnancy, 1.5% were using NFP.National Survey of Family Growth Use of Contraception and Use of Family Planning Services in the United States: 1982-2002. Advance Data No. 350

NFP is also practiced by many Protestant Christians.

Benefici

I propositori dei metodi contraccettivi naturali ritengono che questi aiutino ad aumentare la soddisfazione sessuale della coppia e a diminuire le probabilità di divorzio. La teoria della luna di miele (honeymoon theory ?) ritiene che l'astinenza periodica programmata forzi le coppie ad esprimere l'amore in modo non genitale e ad apprezzare maggiormente i mementi di intimità; inoltre la consapevolezza dei periodi di fertilità costringe ad un maggiore dialogo tra uomo e donna sui propri corpi e questo potrebbe aiutare a rinforzare le abilità comunicative all'interno del matrimonio.

Anecdotal evidence and small studies Marital Duration and Natural Family Planning. Accessed October 2005. are put forth in support of this view. One study involving 505 women using NFP found a correlation between lower divorce rates and the use of NFP.Divorce Rate Comparisons Between Couples Using Natural Family Planning & Artificial Birth Control To date, no studies exploring a cause and effect relationship between the use of NFP and lowered divorce rates have been performed.

Non esistono provati effetti collaterali dei metodi contraccettivi naturali, a differenza dei contraccettivi chimici ed ormonali

Svantaggi

Come la pillola ed altri contraccettivi non meccanici, il riconoscimento della fertilità non offre alcuna protezione contro le malattie sessualmente trasmissibili. È richiesto uno sforzo costante e regolare per determinare quando le probabilità di concepire siano basse. Like the Pill and other non-barrier contraceptives, FA offers no protection against sexually transmitted diseases. FA methods do require regular, consistent effort to determine when a couple's chance of fertility is low. For many women, the times of high fertility coincide with the time of highest libido. The "scheduling" of sex required can be inconvenient for partners who do not live together and are unwilling to abstain or use non-procreative forms of sex when they are able to spend time together. For these reasons, other methods are more popular than FA among large sections of society.

L'osservazione o il tocco del muco della cervice è un'attività che alcune donne trovano sgradevole.

Il tracciamento della temperatura basale diventa difficile e può condurre a risultati imprecisi se il soggetto ha un ciclo sonno-veglia irregolare, ad esempio per motivi di lavoro o familiari (ad esempio la cura di neonati).

Alcune donne trovano un maggiore appagamento sessuale durante i periodi fertili in cui deve essere osservata l'astinenza.

Le coppie che desiderano un basso tasso di rischio di gravidanza (minore di 1% per anno) possono doversi astenere per più di metà di ogni ciclo metruale.

The NFP methods that encourage breastfeeding infertility can only be used until the woman's first post-partum menstruation. Even the most strict form results in average return of menses at 14 months post-partum, and menstruation can return as early as 6 weeks post-partum.

It has been suggested that pregnancies resulting from method failures of NFP, particularly the more reliable methods such as fertility awareness, are at increased risk of miscarriage and birth defects due to aged gametes at the time of conception. To date, no conclusive studies have been performed.Gray, RH. Aged gametes, adverse pregnancy outcomes and natural family planning. An epidemiologic review. Contraception. October 1984. 30(4):297-309.

Some schools of NFP teach that orgasmic acts outside of intercourse are incompatible with the correct practice of NFP. Some couples are not comfortable with this restriction.

Aspetti religiosi

Catholic doctrine holds that God created the marital act to be both unitive and procreative. Deliberately altering fertility or the marital act with the intention of preventing procreation is considered to be a grave sin. Thus, artificial birth control methods and orgasmic acts outside of full marital intercourse are forbidden. Not having sex at all (abstinence) can be considered moral. Having sex at an infertile time in a woman's life (such as pregnancy or menopause) can also be moral since the infertile condition is considered to be created by God, rather than as an act by the couple intended to frustrate fertility.

Thus, it is considered morally acceptable to abstain during the fertile part of the woman's menstrual cycle. Increasing the infertile period through particular breastfeeding practices — the Lactational Amenorrhea Method — is also considered a moral way to space a family's children.

The benefits of spacing children are recognized by the Catholic Church, and use of Natural Family Planning for this reason is encouraged. Humanae Vitae cites "physical, economic, psychological and social conditions" as possibly compelling reasons to avoid pregnancy. Couples are warned, however, against using NFP for frivolous, selfish, or materialistic reasons. Many Catholic sources extol the benefits children bring to their parents, their siblings, and society in general, and couples are encouraged to have as many children as their circumstances make practical.

Riferimenti

Bibliografia

  • Garden of Fertility di Katie Singer.
  • Taking Charge of Your Fertility di Toni Weschler.
  • The Art of Natural Family Planning di John and Sheila Kippley.

Collegamenti esterni

Organizzazioni

Laiche

Cattoliche

Descrizioni delle tecniche

Siti laici

Siti religiosi
non tutti questi collegamenti contengono materiale religioso

Software

questi software sono unicamente disponibili in lingua inglese

Contraccezione

Symptothermale Methode | Fertility awareness | Planification familiale naturelle | Simptoterminis metodas | Periodieke onthouding | Naturalne planowanie rodziny

 

This article is licensed under the GNU Free Documentation License. It uses material from the "Riconoscimento della fertilità".

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