Find accurate definitions of over 5,000 Catholic terms and phrases (including abbreviations). Based on Fr. John Hardon's Modern Catholic Dictionary, © Eternal Life. Used with permission.
NATURAL FAMILY PLANNING (practice)
A method of determining the fertile and infertile days of a woman. There are three methods currently in use and all rely on the observation and recording of one or more signs of the body: 1. The sympto-thermal method. This is the most comprehensive and surest of the three. It involves the observation and recording of all three signs: a. mucus secreted in the cervical opening: the average menstrual period lasts from three to seven days. Toward the end of this period mucus begins to appear at the opening of the cervix. At first it is tacky and yellowish. After a couple of days it becomes a stretchy and turns into a whitish color, like that of an egg white. It reaches this peak quality one to two days prior to ovulation. This indicates the time of greatest fertility; b. body temperature: this is recorded with the use of a basal thermometer, which measures body temperature in tenths of degrees. Twenty-four hours after ovulation, the body temperature will rise approximately .4-.6 degree. About the fourth day after the temperature rise it is safe to assume that the infertile days have begun,provided the other signs concur; c. cervical opening: before ovulation, the cervix is open, soft, and high. After ovulation, the cervix is closed, firm, and lengthens. The concurrence of all three signs indicates the days on which a woman is ovulating. From this can be charted her fertile and infertile days. Differences in individual cycles must be taken into consideration; 2. The Billings, or ovulation, method relies solely on the recording of the mucus symptom; 3. The third method relies solely on the temperature symptom. The sympto-thermal method is more than 99 per cent effective for those who are willing to work with it. The Billings method is also reliable but requires a qualified instructor and somewhat more time and instruction.