With natural family planning (NFP; or the symptothermal method), a woman charts her menstrual periods by taking a daily basal body temperature (BBT) and checking cervical mucus to determine when she ovulates. During ovulation, she abstains from sexual intercourse. Although this may also be referred to as the rhythm method, generally the rhythm method does not involve monitoring the signs of ovulation.
When charting is used in conjunction with another form of birth control such as condoms, it is referred to as fertility awareness. In 2002, CycleBeads began a media campaign in hopes of increasing women’s interest in natural family planning. CycleBeads are a series of color-coded beads that enable a woman to keep track of her menstrual cycle and avoid sexual intercourse on fertile days. To avoid pregnancy during that time, the woman and her partner would abstain from sex or use a different method of birth control.
How They Work
With natural family planning, a woman takes her BBT every morning before she gets out of bed and records it on a basal body temperature chart. Changes in hormonal levels cause body temperature to rise 0.4° to 0.8°F (0.2 to 0.4°C) immediately before ovulation, and it remains elevated until menstruation begins. A woman using this method monitors her cervical mucus, which becomes thin and stretchy during ovulation to help transport sperm. At other times of the month, cervical mucus is thicker. After 6 months of consistent charting, a woman will be able to estimate the approximate time of ovulation, and she can then either abstain from sexual intercourse or use contraception during her high-risk times (usually this period is between 1 and 2 weeks). Most women who use this method are spacing their pregnancies and are not as concerned about preventing pregnancies.
The rhythm method involves abstaining from intercourse midcycle, when ovulation is probable, but usually does not include BBT or cervical mucus charting. Ovulation kits, available in drugstores, can help women who desire pregnancy to determine their fertile days. Researchers at Duke University are working on a “hydration detection” device that would allow a woman to monitor the water content of her cervical secretions through a small vaginal probe (Jennings, Arevalo, & Kowal, 2004). Increases in cervical secretions would indicate possible ovulation, and a woman using this method would avoid intercourse or use contraception.