Effectiveness of the sympto-thermal method of natural family planning: an international study.
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| Motivated and informed participants were recruited for a statistical evaluation of the effectiveness of the symptothermal method. Couples in five countries were selected on the following criteria: (1) the wife had to be between 19 and 44, (2) the wife had to be of proven fertility by having carried a fetus for at least 28 weeks, (3) the couple must have submitted one satisfactory temperature graph before being accepted, and (4) the couple must have expressed a willingness to submit temperature graphs for 24 months. Of the 1022 couples selected, 826 completed the 2 years: only 35 were lost to follow-up. Cycle length varied from 9 to 98 days, with an average of 28,43 days. Only 205 women had a variation of 8 days or less. A more complete analysis of the menstrual cycle data will be reported in another paper. The 1022 couples contributed 21736 cycles and reported 128 unplanned pregnancies, a rate of 7.47 conceptions per 100 woman-years of exposure. Only 16 pregnancies occurred when the couples were following instructions, giving a theoretical effectiveness of 0,93 pregnancies per 100 woman-years using the Pearl formula. Couples trying to prevent any pregnancies had a failure rate of 4,13%: those only delaying a pregnancy had a failure rate of 14,83%. The symptothermal method used alone had a failure rate of 7,16% while use of contraceptive devices with the symptothermal method had a failure rate of 8,19%. The women in our sample averaged 13 cycles per year. Any valid comparative figure for NFP should be expressed in pregnancies per 1300 cycles according to the modified Pearl index rather than per 1200 months. This gives a pregnancy rate of 7,66% as compared to 7,47% for 1200 months. |
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Author : |
Rice FJ, Lanctot CA, Garcia-Devesa C. |
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categorie : |
Scientific Article |
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| Lanctot Claude Bedford (QC) Canada / |
| Rice F / |
