Natural family planning (NFP), sometimes described as periodic abstinence, is a form of birth control that involves recognizing the natural signs in a woman's fertility. Depending on their goals, couples may choose to time sexual intercourse so that it falls during the infertile phase (to avoid pregnancy) or the fertile phase (to achieve it).
Description
There are several methods for practicing NFP. Reliable forms of NFP, such as the basal body temperature method, the cervical mucus method, and the symptothermal method, have been developed over recent decades. In addition, mothers of newborns can delay the return of their menstrual cycle (and thus, their fertility) by using the lactational amenorrhea method (LAM ). The "old" 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 method has been effectively "obsolete" for at least 20 years.
As well as the religious imperative of many couples using the method, supporters typically advocate NFP because it is free (apart from the purchase of a thermometer and charts), natural (introducing no chemicals into the body nor artificial devices to modify the sex act), and the only family planning method that involves both the man and the woman equally (since the two must communicate with each other in order to be aware of the woman's cycle and weigh their feelings about having children). For detractors, however, the latter "benefit" is in fact regarded as a disadvantage.
NFP is also unique among family planning methods in its ability to help couples conceive: the same knowledge of fertility patterns is used to time intercourse optimally to achieve pregnancy. Teachers of NFP report many cases in which couples experiencing difficulty conceiving have been helped in this way, avoiding recourse to invasive medical procedures.
NFP 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 NFP among large sections of society.
Statistics
The effectiveness of NFP, as of artificial forms of contraception, needs to be assessed two ways: method effectiveness and user effectiveness. The method effectiveness is the proportion of women correctly using the method who do not get pregnant. User effectiveness is the proportion of women using the method who do not get pregnant. 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.
The most effective forms of NFP have approximately 99% or higher method effectiveness according to recent studies (e.g., Hilgers, et al., 1998; Ecochard, et al., 1998). User effectiveness is significantly lower. For instance, in one study, a Creighton method achieved 99.5% method effectiveness but only 96.8% user effectiveness (Hilgers, et al., 1998). In another study, a Creighton method 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 (Howard and Stanford, 1999). Ecochard, et al. (1998) found 98.9% method effectiveness in the cases they studied but only 93.5% user effectiveness. Given that user effectiveness depends on various individual factors, the high variability in user effectiveness figures is to be expected.
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 and Stanford, 1999; anonymous, 1999), i.e., the couple knowing that the woman is likely to be fertile at the time, but engaging in sexual intercourse nonetheless. An NFP 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 NFP, but simply as a decision not to use NFP.
While the calendar method (by itself) is not the most reliable form of NFP, over a term of one year, some studies (by Planned Parenthood and, the US Food and Drug Administration) estimate that less than 25% of women in sexual relationships who use the calendar method precisely will get pregnant, while others by NFP proponents estimate the pregnancy rate at only about 9%. Even the pessimistic estimate is much lower than chance (85% of women not using any contraceptive methods will become pregnant in one year), while even the optimistic one is considerably higher (that is, less effective in preventing pregnancy) than optimally-used hormonal contraceptives (i.e. the pill).
Also interesting to note: studies have indicated little or no difference in frequency of intercourse among couples using natural family planning (with such couples thus more sexually active during the infertile phases of the cycle).
Measurement
In most women the menstrual cycle lasts between 24 and 32 days. It starts with a menstrual bleeding. Ovulation takes place at some time between day 12 and day 18. Ova die if not fertilized within 24 hours of ovulation. Spermatozoa are able to fertilize an ovum for a period of about three days after they have been ejaculated, although exceptional cases of fertilization almost one week after intercourse have also been reported.
The period from the start of menstruation to ovulation lasts between 12 and 18 days, depending on the length of the cycle (24 to 32 days). Eliminating the seven days during which sperm can survive in a woman's body, this leaves a first infertile period of five to eleven days from the beginning of menstruation. (Of course, during the first four or five days of this period, the woman will be menstruating.) The second infertile period occurs after ovulation. The time of ovulation can vary, especially if the cycle is not completely regular. Thus, if the couple wished to avoid conception, they must abstain from intercourse for the first four days after the expected time of ovulation as well. Thus, the second infertile period starts on day 16 after the beginning of menstruation in a woman with a 24-day cycle, and on day 22 in a woman with a 32-day cycle. The woman can then be considered infertile until the next menstruation starts.
Observational Methods
NFP methods which not only keep track of the woman's menstrual cycle, but also make observations about the state of a woman's body, offer additional information for couples to use when considering having intercourse.
The basal body temperature method is based on the fact that two or three days after ovulation, hormonal changes cause a rise in body temperature between 0.3 and 0.9C (0.5 and 1.6°F) that lasts at least until the next menstruation.
The cervical mucus method (or Billings method, or Ovulation method , or Billings ovulation method) involves checking the texture of the mucus secreted by the cervix. When a woman is not fertile, the mucus is light or sticky. During the day before and the day of ovulation, (the most fertile time period), the increase in estrogen levels causes more copious mucus that is clear and slippery.
The sympto-thermal method combines the techniques discussed above. Some women may also check the position and feel of their cervix, and note breast tenderness or ovulatory pain (mittelschmerz), the lower abdominal pain or cramping some women feel around the time of ovulation. According its proponents, the symptothermal method can achieve a 99% effectiveness level for a well-instructed and well-motivated couple.
The saliva method involves examining saliva under a microscope for fern-like structures that indicate ovulation.
The lactational amenorrhea method (LAM ) of contraception makes use of the natural infertility which occurs through breastfeeding. It is 99% effective during the first six months postpartum in about 90% of women who:
- Breastfeed their infants exclusively
- Pacify their infants at the breast, not with pacifiers or bottles
- Breastfeed often
- Sleep with their infants
- Are not separated from their infants for more than three hours a day
- Take daily naps with their infants
Obviously, this method is only practical for women whose lifestyles allow for it (though this can be said of all methods of birth control.)
Religion
Total abstinence and NFP (including observational methods and rhythm) are the sole methods of birth control permitted by the Catholic Church.
Citations
- Anonymous (1999) "European multicenter study of natural family planning (1989-1995): efficacy and drop-out", Advances in Contraception 15(1):69-83
- 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):291-6
- Hilgers T.W. and Stanford J.B. (1998) "Creighton Model NaProEducation Technology for avoiding pregnancy. Use effectiveness", Journal of Reproductive Medicine 43(6):495-502
- 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):391-402
See also
External Links
Last updated: 10-16-2005 16:59:10
