Self-efficacy in the use of Natural Family Planning means achieving not only method, but couple autonomy. The couple must first learn to understand the signs of their cyclic fertility. The man is fertile all the time; the woman is fertile only when mucus keeps her husband's sperm alive in her body until ovulation, and for the extent of the life of the ovum. Once the mucus pattern has been understood, the couple needs to become comfortable with living with their rhythm of infertility and fertility. To do so requires communication. Respecting one's cycle demands respect for one's body, hence respect for the person. Couples find that living with their combined fertility changes their relationship to one of greater mutual consideration and respect.
All methods of family planning - natural or artificial - have unplanned pregnancies associated with their use. No method is 100%. Unlike contraception, natural family planning can be used either to achieve or to avoid pregnancy. Initially, investigators classified unplanned pregnancies into method failures and user failures. Method failures occurred when the method had been used correctly and consistently, user failures when the method was either not correctly understood or incorrectly used. Later, the concept of extended use effectiveness was introduced: any pregnancies which occurred when acceptors had discontinued the use of the contraceptive, but before using a different one, were classed under extended use-effectiveness, unless the woman has indicated that she wished to achieve pregnancy. While contraception uses a medication, device, or technique (such as withdrawal) to prevent conception, natural methods demand recognition of the fertile phase, and abstinence during the fertile phase according to the rules of the method, if pregnancy is to be avoided. Both the Pearl Formula - the number of unplanned pregnancies per 100 woman years:
P.R = N unplanned pregnancies x 1200 (or 1300)
N exposure cycles
- and the Life Table have been used to gauge the effectiveness of family planning methods. Natural Family Planning users differentiate between: 1) Method-related pregnancies: the method has been used correctly and consistently; 2) Teaching-related pregnancies: misunderstanding of the method due either to poor teaching or poor learning or both; and 3) Informed choice pregnancies: pregnancy was not planned, but the couple chose to have intercourse on a day of recognised fertility. Most recently, Trussell et al. introduced the concept of "perfect use" and "typical use" to evaluate unplanned pregnancies. Perfect use is similar to method-related pregnancy, while typical use includes all of the user factors. Rates are computed separately to permit better identification of factors leading to unplanned pregnancy. As most NFP trials found fewer than 2% method related pregnancies, the new terminology makes little practical difference. The frequently cited 1978 World Health Organization trial of the Ovulation Method found only slightly higher method related pregnancies (2.8%) and user-related pregnancies (19%). More recent studies have shown far lower unplanned pregnancy figures as teachers become more experienced (Table 1).
Current NFP Effectiveness Studies Ranked by Pregnancy and Continuation Rates. Life Table Rates are Cumulative Net Pregnancies at One Year or 13 Cycles. Method: OM-Ovulation Method; MMM-Modified Mucus Method; ST-Sympto Thermal Method. Continuation Rate is the percent of acceptors who are still using NFP for pregnancy avoidance at one year, irrespective of their reason for discontinuation.
| Table 1 | |||||
|---|---|---|---|---|---|
| One Year (Total) Unplanned Pregnancy Rate | |||||
| Country | Year | Method | Life Table | Pearl Rate | Continuation Rate |
| Indonesia | 1990 | OM | 2.5 | 89.6 | |
| Liberia | 1993 | ST/OM | 4.3 | 78.8 | |
| Nepal | 1986 | MMM | 7.3 | 45.0 | |
| Zambia | 1993 | ST/OM | 8.9 | 71.2 | |
| Indonesia | 1990 | MMM | 10.3 | 81.2 | |
| Kenya | 1988 | OM | 10.5 | 46.0 | |
| Korea | 1988 | OM | 13.4 | 57.0 | |
| Bangladesh | 1988 | OM | 14.9 | 72.0 | |
| India | 1991 | MMM | 2.0 | N.A. | |
| Germany | 1992 | ST | 2.3 | 92.9 | |
| UK | 1991 | ST | 2.7 | N.A. | |
| Italy | 1988 | ST | 3.6 | 100.0 | |
| China | 1994 | OM | 7.0 | 86.0 | |
| Europe | 1993 | ST | 2.5 | 48.0 (9 countries, 14 sites) | |
| Liberia | 1994 | OM/ST | 1.5 | 93.7 | |
| Liberia | 1994 | MMM | 6.6 | 66.0 | |
| India | 1994 | OM | 11.6 | 76.4 | |
| China (8) | 2000 | OM | 0.51 | 97.4 | |
| U.S. | 1994 | OMCr | 12.8 | 78.0 (Creighton Model) | |
Calendar Rhythm calculates the fertile and infertile days of the cycle based on the life of the corpus luteum plus sperm survival in cervical mucus.
The most conservative systems assume maximum life for both: 16 days for corpus luteum survival and 5 days putative sperm survival. Thus a woman who knows the length of her last 6 cycles subtracts 21 days from the shortest cycle in order to know the number of early infertile days. Other systems subtract 20 days or 19 days. Since normally, corpus luteum life is no less than 11 days, one may calculate 10 days from the longest previous cycle in order to know the first late infertile day. Some groups subtract 11 days. For example, if one woman's cycles ranged from 27-35 days in length, her last early infertile day would be Day 6 of the cycle and her first late infertile day would be Day 24.
Calendar rules are retained to identify the early infertile days, but superseded by any appearance of mucus, which signals the beginnin of the fertile phase. Postovulatory infertility is identified in the following ways:
After peak has been identified, the thermal rise is considered to have occurred if the first two higher temps. are at least 0.2¡F, and the third is at least 0.4¡F above the last 6 low temps.
- in the presence of a strong thermal shift, infertility begins on the evening of the 3rd day (or more) of full thermal shift, simultaneously crosschecked by 2 (or 3) days of drying up past the peak day.
- used for temperature patterns not as strong or clear as Rule A, and a mucus pattern not as clear of helpful.
- Postovulatory infertility begins the evening of Peak day + 3 cross checked by 3 days of strong thermal shift. Four or more days of drying up or dryness corroborated by temperature sign of:
Kippley adds calendar calculations for the determination of the early infertile days.
Note: Changed mucus is present after peak in most women. Peak is the last day of mucus with fertile characteristics: lubricative, stretchy, clear or cloudy. See Ovulation Method, below.
To learn the method to avoid pregnancy:
In the first cycle, refrain from intercourse and any genital contact from the beginning of the cycle until the mucus peak has been identified, and for three full days after peak. Once the mucus pattern has been observed, apply the:
1. Avoid days of menstruation
2. The basic infertile pattern (BIP):
3. If the B.I.P. is dry days after menstruation, any change in sensation or appearance of the discharge at the vulva signifies possible fertility.
4. When the B.I.P is an unchanging discharge, any change in sensation or appearance at the vulva signifies possible fertility. It requires three average length cycles to become accustomed to this point of change, during which time the couple should confine intercourse to the post-ovulatory days, according to the Peak rule. In the event of a "patch" of mucus -- one or more days of non-changing mucus followed by dryness, or if there is any bleeding or spotting outside of menstruation, avoid all days of mucus, bleeding, or spotting, and wait until the fourth evening after the last fertile sign to resume intercourse (the "wait and see" rule).
5. When ovulation is delayed, so that the pre-ovulatory phase is more than three weeks, the B.I.P. can then be studied for a period of 2 weeks. It may be:
The Early Day Rules are applied in all these circumstances.
6. When returning to fertility during or after lactation, wait until the fourth evening after the first two menses.
7. The early day rules apply in all special circumstances: lactation, weaning, premenopause, discontinuation of anovulant medication - any anovulatory state.
8. The Peak Rule: Wait until the fourth day after peak to resume intercourse. After the peak rule has been observed, there are no rules.
Identify the fertile pattern as above. Intercourse on Peak or the day after is most likely to achieve pregnancy.
1, 2,