Efficacy of methods for determining ovulation in a natural family planning program

Objective: To evaluate the efficacy in ovulation detection of methods used in natural family planning in comparison with pelvic ultrasonography. Design: Prospective analysis of ovulation detection by natural family planning methods and ultrasonography. Setting: Natural family planning clinic, Department of Obstetrics and Gynecology, University of Naples 'Federico II'. Patient(s): Forty healthy women who were highly motivated to use natural family planning. Intervention(s): None. Main Outcome Measure(s): Transvaginal ultrasonographic findings, urinary LH levels, salivary β- glucuronidase activity, salivary ferning levels and characteristics of cervical mucus, and BBT. Result(s): Urinary LH level determination yielded a 100% correlation with the simultaneous ultrasonographic diagnosis of ovulation. Mucus sensations and characteristics yielded a 48.3% correlation when simultaneously evaluated with ovulation. β-Glucuronidase levels yielded a 27.7% correlation. The salivary ferning test had a 36.8% ovulation- detection rate the day of ovulation, but 58.7% of results were uninterpretable. Body temperature measurements yielded a 30.4% correlation with the simultaneous ultrasonographic diagnosis of ovulation. Conclusion(s): Measuring urinary LH levels is an excellent method for determining ovulation. Although variations in mucus characteristics and basal body temperature correlate somewhat with ovulation, the length of the fertile period is overestimated with these methods. The salivary ferning test and measurement of β-glucuronidase levels are not good methods for home ovulation testing.