Effectiveness · Typical and Perfect Use
Ecochard R et al., 1998 · Contraception, fertilite, sexualite (1992)
The analysis concerned 626 users using NFP in order to avoid a conception during a total of 6740 cycles. Participation in the study did not interfere with their plan of conception, and they were invited to behave, as far as possible, as though they ignored the study. Of these 626 couples, 530 were french, 61 belgian and 35 swiss. On the whole, 39.3% used birth control to limit births and 60.7% to space them. The observed pregnancy rates are 1.13, 6.47 and 17.58 for one year in actuarial method respectively for method, method + user and total pregnancy rate. The pregnancy rate was higher for women before 35 years (RR: 3.8; 95 p100 confidence interval: 1.4-10.3), during the six months after delivery (RR: 2.5; 1.0-4.6) and, of course, for couples with inprotected sexual intercourse in fertile phase (RR: 4.8; 2.1-11.2). NFP can be placed among methods of great theorical effectiveness. But pregnancies as a result of intercourses during the fertile phase despite its identification are frequent: couples have to be informed.
Effectiveness · Typical and Perfect Use
Gallagher J, 1983 · Aust Fam Physician
When properly taught and practised, natural family planning can be a highly effective form of birth regulation. Recent studies indicate low failure rates of less than three pregnancies per 100 women years for couples with a strong motivation to follow the method. Studies show that pregnancy rates are high when the rules for avoiding pregnancy are not adhered to. Successful natural family planning can lead to heightened self esteem and marital enrichment.
Effectiveness · Typical and Perfect Use
Trussell J et al., 1990 · Fam Plann Perspect
Previously published estimates of probabilities of method and user failure for all contraceptive methods suffer from a serious methodological error and are biased downward, with the extent of bias unknown. Data from a World Health Organization clinical trial of the ovulation method of periodic abstinence were used to provide the first correctly calculated measures of method and user efficacy and to determine the characteristics that distinguish women who consciously take risks from those who do not. Probabilities of pregnancy during the first year are 3.1 percent during perfect use (method failure) and 86.4 percent during imperfect use (user failure). Thus, if used perfectly, the ovulation method is very effective. However, it is extremely unforgiving of imperfect use. Because perfect compliance is difficult for many couples who desire intercourse when it is forbidden by ovulation method rules, and because the risk of pregnancy during imperfect use is so great, the ovulation method cannot be considered an ideal contraceptive method for the typical couple, who are likely to be less compliant than couples who volunteer for a clinical trial. The probability of an accidental pregnancy is greatest when any of the three most serious rules--no intercourse during mucus days, within three days after the day of peak fecundity or during times of stress--are broken. Those who have a poor attitude toward the rules are more likely to take risks, including serious risks. Those who get away with taking a risk (i.e., do not get pregnant) are very likely to take risks again. Because breaking the most serious rules entails a 28 percent risk of pregnancy per cycle, those likely to take risks should be counseled about the probable consequences.
Use and Experience · User Satisfaction
France M et al., 1997 · Adv Contracept
This study has determined long-term continuation rates of clients who attended clinics of the New Zealand Association of Natural Family Planning and became autonomous users. It has also identified factors which might influence the continuation of NFP use. A total of 509 female subjects, 452 of them with their male partners, were enrolled in the study at the beginning of clinic teaching. Once autonomous they were sent questionnaires at 6-monthly intervals for a period of 24 months. Time out was allowed for pregnancy. The number of female subjects entering the 2-year follow-up phase of the study was 406 (79.8%). Of these 164 completed 2 years of use with 102 (20% of study entrants) using NFP and 62 (12.2%) using fertility awareness in combination with a barrier method. Subjects for whom NFP was their first family planning method, who were Catholic or who gave religion as their reason for choosing NFP were more likely to continue long-term use. The majority of subjects (> 90%) were highly satisfied with NFP use, with the most common reasons for satisfaction being self-awareness, freedom from drugs, naturalness and effectiveness. The difficulties reported related to abstinence and cycle interpretation.
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