Objective:  To determine variability in the phases of the menstrual cycle among healthy, regularly cycling women. Design:  A prospective descriptive study of a new data set with biological markers to estimate parameters of the menstrual cycles. Participants:  One hundred forty one healthy women (mean age 29 years) who monitored 3 to 13 menstrual cycles with an electronic fertility monitor and produced 1,060 usable cycles of data. Measures and Outcomes:  Variability in the length of the menstrual cycle and of the follicular, fertile, and luteal phases, and menses. The estimated day of ovulation and end of the fertile phase was the peak fertility reading on the monitor (i.e., the urinary luteinizing hormone surge). Results:  Mean total length was 28.9 days (SD= 3.4) with 95% of the cycles between 22 and 36 days. Intracycle variability of greater than 7 days was observed in 42.5% of the women. Ninety‐five percent of the cycles had all 6 days of fertile phase between days 4 and 23, but only 25% of participants had all days of the fertile phase between days 10 and 17. Conclusions:  Among regularly cycling women, there is considerable normal variability in the phases of the menstrual cycle. The follicular phase contributes most to this variability. JOGNN, 35, 376‐384; 2006. DOI: 10.1111/j.1552‐6909.2006.00051.x.

Background:The aim was to compare the efficacy and acceptability of two Internet-based fertility awareness based methods of family planning (FABM).Study Design: Six hundred and sixty-seven women and their male partners were randomized into either an electronic hormonal fertility monitor (EHFM) group or a cervical mucus monitoring (CMM) group. Both groups utilized a web site with instructions, charts, and support.Acceptability was assessed online at 1, 3, and 6 months. Pregnancy rates were determined by survival analysis. Results:The EHFM participants (N=197) had a total pregnancy rate of 7 per 100 users over 12 months of use compared with 18.5 for the CMM group (N=160). The log rank survival test showed a significant difference (p < .01) in survival functions. Mean acceptability for both groups increased significantly over time (p < .0001). Continuation rates at 12 months for the monitor group were 40.6% and the mucus group 36.6%. Conclusion:In comparison with the CMM, the EHFM method of family planning was more effective. All users had an increase in acceptability over time. Results are tempered by the high drop-out rate.

Background: Menstrual cycle function may continue to be altered after

Abstract:Objective: To determine the effectiveness of an electronic hormonal fertility monitor plus cervical mucus monitoring to avoid pregnancy. Design: A 12-month prospective clinical efficacy trial. Setting and Participants:One hundred ninety-five (195) Conclusions: Correct use of an electronic hormonal fertility monitor with cervical mucus observations can be as effective as other fertility awareness -based methods of natural family planning. Comparative studies are needed to confirm this conclusion.Approximately 124,000 women in the United States use natural methods of family planning (i.e., cervical mucus or temperature monitoring) for avoiding pregnancy (Mosher, Martinez, Chandra, Abma, & Wilson, 2004). Another 434,000 use self-devised calendar formulas (i.e., rhythm) as a means to avoid pregnancy. Many women rely on natural markers of fertility to help them achieve pregnancy. The accuracy, ease of use, acceptability, and effectiveness of natural biological markers to estimate the time of fertility in the menstrual cycle is important for these women. When NFP methods are used according to instructions (which is referred to as correct use), the unintended pregnancy rate can be as low as 1 to 3 per 100 users over a 12-month time period, and when the instructions are not always followed (which is called imperfect use), the unintended pregnancy rate can be as high as 25 per 100 users over 12 months (Trussell, 2004). The large difference between correct-and imperfect-use unintended pregnancy rates is due to the considerable overestimation of the 6-day fertile window (when correct use is calculated) and to difficulties in the complexity of learning and using NFP methods, the length of required abstinence, subjectivity of the biological markers to estimate the fertile window, and variability of the menstrual cycle (Burkman, 2002 ;Trussell).The purpose of this study was to determine the effectiveness of using a new high-tech hormonal fertility monitor called the Clearblue Easy Fertility Monitor (CEFM) (Inverness Medical Innovations, Waltham, MA) along with another natural marker of fertility (i.e., cervical mucus monitoring) as a means to avoiding pregnancy. The CEFM is a handheld home-use device that estimates fertility by measuring urinary metabolites of estrogen and luteinizing hormone (LH) (May, 2001). The monitor is intended as an aid for achieving pregnancy. However, it could be useful for women and couples who wish to avoid pregnancy as well. Background Studies

by Inverness Medical Innovations) is intended as an aid for achieving pregnancy. However, the information it provides is also useful for women and couples who wish to avoid pregnancy.