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Am Fam Physician. 2000;61(6):1816

Controlling reproduction is a major component of preventive medicine. In recent years, there have been new developments in the area of natural family planning. These have included home measurement of urinary luteinizing hormone (LH) levels and evaluation of salivary activity and cervical mucus characteristics. Despite the availability of these methods, few studies have evaluated their effectiveness in determining ovulation. Guida and associates studied the effectiveness of natural family planning programs in determining ovulation and the fertile period.

Forty women who sought natural family planning advice were enrolled in the study. All were followed for six months while using these methods to become familiar with them. The methods used included urine dip-stick measurements for LH levels, salivary β-glucuronidase activity, salivary ferning, cervical mucus levels and characteristics, and basal body temperature measurements. Data from these measurements were compared to results of transvaginal ultrasound examinations that were performed daily starting at day 7 of the menstrual cycle. Ovulation was defined as the first day a corpus luteum was visualized.

The correlation between urine LH levels and ovulation was 100 percent. Cervical mucus sensation and characteristics had a 48 percent correlation, while the next best test was salivary ferning, with a 37 percent correlation. However, more than 50 percent of the salivary tests were considered uninterpretable. The salivary β-glucuronidase activity test correlated with ovulation less than 30 percent of the time.

The authors conclude that use of home urine LH dip-stick measurements is an excellent way to determine time of ovulation. This method also minimized the period of sexual abstinence. The other methods tend to overestimate fertility. The salivary and β-glucuronidase methods are not good predictors of ovulation and should not be used in natural family planning.

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