Grant Title

Randomized Comparison of Two Internet –Supported Natural Family Planning Methods

Document Type

Unpublished Paper


Problem Statement: The length of periodic abstinence, due to overestimation of the fertile phase of the menstrual cycle is often a reason for dissatisfaction, discontinuation, and user error with natural family planning (NFP) methods. The objective of this research was to compare the length of required abstinence (i.e., estimated fertility) and coital frequency between two NFP methods.

Study Design: Analysis of existing data from a 12 month prospective comparison study in which participants were randomized into either an electronic hormonal fertility monitor (EHFM) group or a cervical mucus monitoring (CMM) group, both of which included a fertility algorithm as a double check for the beginning and end of the estimated FW. The current study involved 197 women (mean age 29.7, SD=5.4) who used the EHFM to estimate the FW and 162 women (mean age 30.4, SD=5.3) who used CMM to estimate the FW. They produced 1,669 menstrual cycles of data. Number of days of estimated fertility and coitus was extracted from each cycle and t-tests were used to compare the means of these two variables between the two NFP methods.

Results: After six months of use, the EHFM group had statistically fewer days of estimated fertility than the CMM group (13.25 days, SD=2.79 versus 13.65 days, SD=2.99; t=2.07, p = .04) and significantly more coitus (4.22 coital acts, SD=3.16 versus 4.05 acts, SD=2.88, t=1.17, p=.026).

Conclusion: The use of the EHFM seems to provide more objectivity and confidence in self-estimating the FW and use of non-fertile days for intercourse when avoiding pregnancy.