Comparing different methods of fertility regulation

There are two Tables on this page, Table 4-1 and Table 4-2.

  • Table 4-1 lists studies of the  effectiveness of the Symptothermal method of NFP using the Pearl Index
  • Table 4-2 compares the effectiveness of various family planning methods, for ‘Perfect Use‘ and ‘Actual Use’, using the Pearl Index. The NFP figure that is included is for ‘Actual Use‘ only.

Table 4-1:  STUDIES ON THE EFFECTIVENESS OF NFP , (STM) – PEARL INDEX 

Comment on Table 4-1: Table 4-1 outlines the effectiveness of the ‘symptothermal method’ (STM) of natural family planning in avoiding pregnancy, as documented in recent European studies using the Pearl Index.
Studies of Symptothermal (STM) NFP Method – Pearl Index
Location of the study Year Pearl Index (PI) Ref
Germany (Double-Check Method) 2007 1.8, (0.4)* 1
Germany (STM); (Double-Check Method not specified) 1991 2.3 2
Europe (Double-Check Method) 1989- 92 2.5 3

Table 4-1; Effectiveness studies (Pearl Index): Results showing the effectiveness of the symptothermal method of NFP in pregnancy avoidance as measured by the Pearl Index. (Table 4-1 is adapted from the article on the internet by David Aldred 4; * the figure in brackets is for ‘perfect use’, i.e. the use of the method strictly adhering to its rules. The remaining figures are ‘actual use’ figures, i.e. the ‘use effectiveness’, which is the sum of all the unintended pregnancies whether due to method or user failure).

References:

  1. Frank-Hermann P.et al; ‘The effectiveness of a fertility awareness based method to avoid pregnancy inrelation to a couple’s sexual behaviour during the fertile time: a prospective longitudinal study; Human Reproduction; Feb 2007; p1-10.
  2. Frank-Herrmann et al; ‘Effectiveness and acceptability of the symptothermal method of natural family planning in Germany; Am J Obstet Gynecol 1991; 165; 2052-4
  3. Freundl G.; Prospective European multi-center study of natural family planning (1989-1992): interim results; Advances in contraception; 1993, 9; 269-283.
  4. Aldred, David; http://nfpsite.aldred.org/effect.html

Table 4-2: COMPARISON OF NFP EFFECTIVENESS WITH OTHER METHODS OF FERTILITY REGULATION – PEARL INDEX 

Comment on Table 4-2: Table 4-2 Demonstrates that natural family planning is as effective as the contraceptive Pill and IUD in pregnancy avoidance.
Pearl Index for various family planning methods *
Method Pearl Index – ‘Perfect use’ Pearl Index ‘Actual Use’
Contraceptive Pill

(Pearl Index figure from ref 4 below)

 0.1-0.5 3
** Natural Family Planning (NFP), STM Double-Check

(Pearl Index figure  from ref 3 below)

 – 2.5
Intra Uterine Device (IUD)

(Pearl Index figure from ref 4 below)

 1.5 2
Male Condom

(Pearl Index figure from ref 4 below)

 3 12

Table 4-2; Comparison of the effectiveness of NFP with other family planning methods: The ‘actual use’ figures for the various family planning methods quoted in Table 4-2 show that there is no significant difference in the rate of unintended pregnancies in those women who use natural family planning, with those who use artificial methods e.g. the ‘Pill’ or the IUD to regulate fertility. The ‘actual use’ rate for male condom users is significantly higher than for other methods.

*These figures, (other than those for natural family planning), are from the article by David Aldred4 on the internet; NOTE: for the natural family planning figure, see Table 4-1 above, and the text ** below). The effectiveness figures given by Aldred in his article are quoted  from “Contraceptive Technology by Hatcher, Trussell, Stewart et al; 16th edition; Irvington publishers, New York, 1994”, a standard reference text on the subject. However, the  natural family planning figures quoted from ‘Contraceptive Technology’ are not included in Table 4-2 as the authors lump all possible methods of natural family planning together under the term ‘periodic abstinence’ including those which were outdated by the mid 1940s,4  and are not a reliable statistic for modern fertility awareness based (FAB) methods of NFP.  The figure given in Table 4-2 for the Actual Use of the symptothermal double-check method of NFP is taken from Freundl et al.3 (see next paragraph)

**The natural family planning figure quoted in Table 4-2 refers to reference 3 below, i.e. Freundl et al 1989-1992 European study, pages 278, 280 and Table 10 on page 279, as it uses the Pearl index measurement. This figure is the total use-effectiveness of the symptothermal double-check method in 7404 cycles. Use-effectiveness is calculated on the sum of all the unintended pregnancies (UIP) whether due to user or teaching failure, see page 277 of this article.

In Table 4-2, the two ‘perfect use’  figures for the ‘Pill’ are for the combined pill and the progestin-only pill respectively.

Evaluating studies of  NFP effectiveness in pregnancy avoidance:

There is not just one method of NFP. Different NFP methods use different indicators to identify the fertile time and have different rules for abstinence and therefore must be evaluated separately. “The practice of grouping all NFP method together with calendar rhythm masks the differences in the effectiveness of various NFP methods.”5

References:

  1. Frank-Hermann P.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; Feb 2007; p1-10.
  2. Frank-Herrmann et al; ‘Effectiveness and acceptability of the symptothermal method of natural family planning in Germany; Am J Obstet Gynecol 1991; 165; 2052-4
  3. Freundl G.; Prospective European multi-center study of natural family planning (1989-1992): interim results; Advances in contraception; 1993, 9; 269-283.
  4. Aldred, David; http://nfpsite.aldred.org/effect.html
  5. Lamprecht V, Trussell J; ‘Natural Family Planning effectiveness: evaluating published reports’; Adv in contraception; 1997; 12; 155-65
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