Natural Family Planning

What's natural family planning?

The name refers to a variety of methods for predicting the fertile days during a woman's cycle. These techniques are used by couples who are either trying to conceive or trying to avoid pregnancy. Your fertile period lasts from about five days before ovulation to one day after -- but predicting when you'll ovulate each month can be tricky, especially if you're like most women and your cycles aren't perfectly regular. The only sure way to pinpoint it is to count BACK 14 days from the first day of your period. So if you don't want to get pregnant, it's a good idea to add a few more days of abstinence onto each end of that fertile window. Some couples resort to a barrier method like a condom or diaphragm on the woman's potentially fertile days, rather than abstaining from sex.

The following methods require you to take note of the physical signs that ovulation has occurred to help you estimate when you're fertile and when you're not.

The Calendar or Rhythm Method

If you decide to use this method, you'll first need to keep track of how long each of your cycles lasts over the course of a year. Count the number of days from the day you start menstruating to the day before your next period. (The first day of your period is always the first day of your cycle.) Then, to determine the first day of the cycle on which you might be fertile, subtract 18 from the number of days in your shortest cycle during the past year. To identify the day on which you can start having sex again, subtract 10 from the number of days in your longest cycle. If your cycles last between 26 and 29 days, for example, you'll have to avoid intercourse from day 8 through day 19 of each cycle. This is the least effective of the family-planning methods, even for women with regular cycles, and most family-planning clinics no longer recommend it.

The Temperature Method

For this method, you must take your temperature every morning with a highly accurate "basal" thermometer. It's essential to do this as soon as you wake up, even before you've snuggled with your honey or put one foot on the floor. Note your exact temperature each morning on a calendar. The day your temperature rises by 0.40F to 0.8 degrees Fahrenheit is usually the day after you've ovulated. If your temperature remains slightly elevated for the next two days, you'll know that ovulation has occurred. To prevent pregnancy, you must not have unprotected intercourse until three days after you ovulate. But the window of opportunity for carefree sex ends about 9 days later, when your temperature goes back down again as your next menstrual cycle begins. This method isn't reliable when your temperature is already elevated because of illness. Too little sleep can also throw your resting body temperature off.

The Mucus Method

This method involves tracking changes in the amount and texture of your vaginal discharge, the mucus that forms around your cervix and ends up in your panties during each month's cycle. Those changes reflect the rising level of estrogen in your body. For the first few days after your period, you may have no discharge at all. Then you'll notice a cloudy, tacky mucus as your estrogen starts to rise. When the discharge starts to increase in volume and becomes clear and stringy like raw egg white, you'll know that ovulation is near. A return to either tacky, cloudy mucus or no discharge means that ovulation has passed. You should avoid intercourse from the day you first notice the discharge until four days after it's gone back to normal or disappeared. A vaginal infection or the use of vaginal products like douches or medication can produce changes in your cervical mucus and throw off the pattern.

The Symptothermal Method

This is the most reliable of the natural family-planning techniques, since it combines the temperature and mucus methods and adds other indicators that can help predict your fertile period. Some women experience a slight abdominal cramping on the day of ovulation; you may be able to notice this sign if you know roughly when to expect it.

How well do these methods work?

All of them require precise record-keeping and a high level of commitment. When used consistently and correctly, they are about 91 percent effective according to Planned Parenthood, but under typical conditions 12 to 25 out of 100 women who rely on them will become pregnant within a year.


Planned Parenthood. Fertility Awareness-Based Methods. September 2010.

Facts About Birth Control. Planned Parenthood.

June M. Reinisch, Ph.D. The Kinsey Institute New Report on Sex:372-5. New York. St. Martin's Press 1991.

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