Cycle Based Fertility Awareness Methods

Cycle-based fertility awareness methods depend on an understanding of the fertile period in a woman's menstrual cycle and abstaining from sex during those days. These birth control methods are called "natural" by some people because women learn to interpret the normal physical signs of their bodies that signal the beginning and end of fertility each month. However, it is not necessarily natural for couples to avoid having intercourse for many days out of each month, which these methods require.

The rhythm, or calendar rhythm, method was the first of these to be used, and it is still the most common. Other approaches, however, such as the cervical mucus and symptothermal methods, give a woman a better understanding of her physiology and her fertility cycle and are more accurate. The use of calendar rhythm alone is not encouraged today because it leads to many unintended pregnancies.

All the fertility awareness methods are based on the fact that the probability of pregnancy is negligible except for about 10 days in the middle of a typical menstrual cycle. Although typical menstrual cycles may vary from 23 to 35 days in length, with even shorter and longer cycles possible, this "fertile phase" is almost always the same length. The key to the successful use of cycle-based birth control is learning when in the cycle the possible fertile days occur and refraining from sex (or using another form of contraception) during those days. If abstinence is the choice, this can mean avoiding intercourse for one-third to one-half of the month, possibly using other ways to achieve orgasm without intercourse.

Cycle-based methods today are known most often by two labels: natural family planning (NFP) and fertility awareness methods (FAM). Regardless of the label, the techniques used to determine a woman's fertile period are very similar. The difference lies in what is done with the information.

Natural family planning is generally learned within the context of religious beliefs about birth control, and the couples who practice it use abstinence during fertile days to avoid pregnancy. In contrast, couples who practice the fertility awareness method might have intercourse during the fertile days and use a barrier method to avert pregnancy. Fertility observation also can be used chiefly to improve the effectiveness of barrier methods. A woman and her partner can take extra precautions during those days, such as using extra spermi-cide in addition to a diaphragm or condom.

Fertility observation has the important advantages of having no negative side effects and costing very little. In addition, when pregnancy is desired, a woman's awareness of when she is fertile can be useful in helping her conceive.

The disadvantage of these methods is that, to be successful, they require real commitment and diligent practice. More training is needed for them than for other methods of contraception, because the signs of fertility can differ from cycle to cycle and from woman to woman. Couples who master the techniques of fertility awareness, however, and successfully integrate this knowledge into their sexual life can achieve very high rates of success.

The best source for classes in these methods is the Catholic Church, which offers them through "Marriage and Family Life" offices or programs run by local Catholic archdioceses. Classes generally are held once a month for 3 or 4 months and are open to any couple interested in a natural method of contraception, regardless of religious background, or lack of religious background. About one-fourth of those who take such classes are not of the Catholic faith. Catholic hospitals also may offer classes or be able to provide information on local programs.

Like many of the other contraceptive methods, cycle-based birth control does not protect against the transmission of sexually transmitted diseases, including AIDS.


An understanding of what happens in the female body during the course of the menstrual cycle is helpful in appreciating how these techniques work. (Also see Chapter 1 on anatomy.)

The first day of menstruation is day one of the cycle. Menstruation takes place because an egg that was released from an ovary during the preceding weeks was not fertilized and did not implant in the blood-rich endometrium, the lining of the uterus. As a result, the uterus sloughs off the endometrium—and that is menstruation. On the first day of menstruation, a new cycle begins as the pituitary gland releases follicle-stimulating hormone (FSH). As its name implies, FSH activates the follicles of the ovary to enlarge and the egg cells within them to grow. In addition, the follicles begin to secrete estrogen.

As the amount of estrogen in the body increases, the cervix begins to produce cervical mucus in steadily larger amounts. The cervical os (its opening) begins to widen as the mucus becomes abun



A woman uses these methods to recognize changes in her body that indicate the fertile phase of her menstrual cycle. If she does not want to get pregnant, she must not have sex during those days. Women who become very familiar with their body's changes can be successful in preventing pregnancy.

For these methods to work for you, your partner has to be willing to avoid sex during the many days in each month that it is possible to get pregnant. If you are not sure about your safe days or if you and your partner take chances, these methods have a high failure rate.

Classes that teach fertility awareness are available, usually through the Catholic Church.

Fertility awareness methods do not protect against STDs, including AIDS.

dant, watery, and stretchy. The wide open os and the plentiful, "fertile" mucus make it easier for sperm to move swiftly into the uterus and fallopian tubes—toward any egg cell that may be there. The type of mucus secreted at this time protects the sperm from the normal acidic vaginal secretions, which can kill sperm.

While the reproductive tract is becoming hospitable to sperm, the increased level of estrogen also stimulates the pituitary to secrete luteinizing hormone (LH). The resulting surge of LH triggers the release of a mature egg cell from its follicle, so it can be caught by the fimbria and guided into a fallopian tube.

The empty follicle begins to produce progesterone. This hormone stimulates the os to close and the cervical cells to stop making fertile mucus. In most women, it also causes the basal body temperature to rise several fractions of a degree. The temperature remains elevated until progesterone declines, the endometrium begins to be sloughed off, and the menstrual cycle begins again. If the egg has been fertilized and implants itself in the uterus, the endometrium stays in place in order to nurture the egg as it divides and grows, and menstruation does not occur.

A follicle releases an egg (ovulation) approximately 14 days before the onset of menstruation, regardless of the length of an individual woman's menstrual cycle. If the cervical mucus is hospitable, it is believed that sperm can survive in the reproductive tract for as long as 7 days. Eggs can live 12 to 24 hours. Sometimes a second egg is released a day or so after the first, making fraternal twins possible.

Allowing for inaccuracies in the timing of ovulation, even women with regular cycles must assume that they could become pregnant for up to 10 days during each cycle. A woman with an irregular menstrual cycle who wants to be safe from conception must consider her probable fertile period to be as long as 13 to 14 days. Long fertile phases can be a strain for couples who rely on abstinence for unsafe days, although many couples find ways other than vaginal intercourse to reach sexual satisfaction.


Fertility awareness methods of contraception work best for couples who are monogamous, because these methods require sharing the responsibility with a reliable sexual partner. A monogamous relationship is additionally important because these methods often involve unprotected intercourse and do not prevent sexually transmitted diseases.

Good candidates are couples who are strongly motivated not to have children and genuinely do not mind the organization and discipline needed to succeed. Couples who do not mind abstaining from intercourse and are comfortable reaching orgasm by other means also may find these methods suitable.

Men and women who dislike the interruption of certain contraceptives or worry about the side effects of hormonal methods may prefer to combine the fertility awareness approach with a barrier method for fertile days.

Women and men who for religious reasons choose not to use other methods of birth control are also good candidates for cycle-based family planning.

Ovulation predictor kits that are available in drugstores can detect ovulation only 24 to 48 hours beforehand, not soon enough to alert a couple to avoid intercourse, considering the survival ability of sperm. The kits are designed for couples who are trying to achieve pregnancy and cannot be used either to replace or enhance the fertility awareness methods described in this chapter.

It is difficult to establish an accurate failure rate for cycle-based methods. They work better for couples who are older, have used them for a while, and are highly motivated. The most recent estimated failure rates for the first year of using cycle-based methods range from 1 to 25 percent. Among perfect users, first year failure rates have varied from 1 to 9 percent, depending on the individual



method. Among the more typical users, however, 20 percent become pregnant during the first year.

Failure rates are lowest if couples limit unprotected sex strictly to the period after ovulation; failures are more common if unprotected sex occurs before ovulation.

Inadequate teaching, incomplete acceptance of this approach, a high dropout rate, and careless use of the technique are some of the reasons for the failure of cycle-based methods. For best results, it is important to find a health practitioner or family life instructor certified in these methods. They can be learned best from personal instruction, not from reading materials, because a couple may need assistance in changing their sexual attitudes and behaviors. Young women whose periods are just beginning and women who are approaching menopause particularly need skilled input in order to use fertility awareness methods.


Four main fertility awareness methods are practiced today. They can be used alone or, as often happens, can be combined to improve the rate of success. Variations of a particular method also may be taught in some places.

Calendar Rhythm Method

This method was the earliest technique used to establish the fertile and infertile days of a woman's menstrual cycle. It was devised in the 1930s, when it was determined that ovulation usually precedes menstruation by a predictable number of days (approximately 14) every month, regardless of the total length of the cycle. Figuring out the length of the fertile period had to take into account the number of days the egg was thought to be in the fallopian tubes, available to be fertilized, plus the number of days sperm could live in a woman's reproductive tract. This method uses a three-step formula.

Step 1. Make a calendar-like record of the beginning and end of at least eight menstrual cycles. The first day of bleeding, no matter how light, is day one of the cycle. The last day of the cycle is the day before the next menstrual period. After you chart your cycles in this fashion, note the number of days of the longest and the shortest cycles.

Step 2. To calculate the most likely first day of your fertile period, substract 18 days from the number of days in your shortest menstrual cycle. If your shortest cycle was 24 days, subtracting 18 days indicates that day 6 of your cycle is the earliest probable time you could be fertile.

Step 3. To calculate the probable last day of the fertile period, subtract 11 days from the number of days of the longest cycle. If your longest cycle was 33 days, for example, subtracting 11 days from 33 puts the last probable day of your fertile period at day 22.

To avoid pregnancy in this example, you would have to abstain from intercourse, or use a barrier contraceptive, from day 6 to day

22 of your cycle. Your safe period is from day 23, through your next menstrual period, through day 5 of your new cycle, including days

23 and 5. During such cycles, this schedule provides approximately 5 to 6 menstruation-free days per month for unprotected intercourse. Many women have irregular cycles, with the result that their potentially fertile periods, as figured by the calendar method, can be long and their safe periods short.

The best way to keep track of fertile and infertile days is to mark them off each month on a calendar. Even if you have established what your menstrual pattern is, continue to record your cycles by indicating the day each period begins. If your cycles begin to fluctuate considerably in length, so that you seem to have more fertile days than usual, get in touch with the instructor or health practitioner who has been helping you with this method.

Temperature Method

Basal body temperature (BBT) is your resting temperature. By charting your BBT for 3 or 4 months, you can determine when you usually ovulate. Just before ovulation, a woman's BBT typically drops a few fractions of a degree. After ovulation, the BBT usually rises between 0.4 and 0.8 degrees F and remains at that higher level every day until just before menstruation begins. What is important is not the temperature, but the fact that it rose over your normal baseline temperature. If you do not have such a sustained rise in your BBT, you may not have ovulated.

It is vital to take your basal body temperature in the morning before you get out of bed, talk, or take a drink of any fluid, hot or cold. You must also have had at least 3 hours of sleep to get an accurate reading. This means you also can record your BBT if you wake up in the middle of the night, as long as you have had 3 hours of sleep. You can take your temperature orally, rectally, or vagi-nally, but use the same method every time. Leave the thermometer in place for as long as its instructions dictate.

Special BBT thermometers, designed for reading fractional changes in temperature, cost approximately $12 and are available in drugstores. (They register only the temperature range between 90 degrees and 100 degrees F.) To use the thermometer, shake it down to 96 degrees and put it next to your bed the evening before. If you use it rectally, lubricate the bulb. Monthly charts for noting each day's BBT are available from your doctor or your family planning clinic, or you can make your own.

A change in the BBT of only a fraction of a degree is important. Mark each tenth of a degree with a dot on your chart. Connecting the dots makes it easy to see the day-to-day changes. After you have charted each day's temperature for several months, you will begin to see a pattern. Your temperature changes may be steep, gradual, or in steps. Your chart may contain some unexpected blips that represent a sleepless night or an emotional upset, but that does not affect the overall pattern. If there are unusual high or low readings any morning and you can figure out the cause, make a note on the chart to help you interpret the readings later on.

You should see a pattern of 1 to 3 low-temperature days before ovulation—the highly fertile days—and then a progesterone-caused rise in temperature. After 3 days of higher temperature you are safely infertile. Because the temperature rise is triggered by proges terone produced after ovulation, this method cannot be used as an advance warning of ovulation. It is an indication, however, that ovulation has taken place and the fertile period is about to end.

The safest way to use the BBT method is to abstain from intercourse or use a barrier method through the first half of your cycle.

There are several events other than ovulation that can cause a rise in BBT. They include:

• Illness accompanied by a fever can cause variations in your current cycle and in the next one. A low-grade infection, cold, or flu can cause a rise of a few tenths of a degree, enough to affect the BBT.

• Alcoholic drinks in the evening may cause a rise in the BBT the next morning in some women.

• Taking your BBT later than usual may result in a higher reading. If this happens, record the time difference on your chart.

Cervical Mucus Method

The technique commonly used today by women to recognize the variations in their cervical mucus was developed in the 1970s by Drs. John and Evelyn Billings. A more standardized version is widely taught in the United States as the Creighton model.

The mucus method is useful for determining when before ovulation it may be possible to have unprotected sex without conceiving. Recognizable changes in mucus can signal the onset of the fertile period more clearly than does the BBT. After ovulation, however, the basal body temperature may be a more accurate way of knowing when your infertile period has begun and you can have unprotected sex.

The secretions from the cervix change during the course of each month. The days immediately following menstruation are called the "dry" days, when the cervix secretes very little mucus. These days are considered fairly safe for unprotected intercourse because ovulation is unlikely, and there is no mucus to help sperm survive the naturally acid environment of the vagina. (Some women do not have dry days, especially if they have very short cycles.)

After the few dry days, the mucus is still skimpy, but becomes sticky to the touch, does not stretch, and appears somewhat white, yellow, or cloudy. (Appearance can vary from woman to woman.) This mucus usually is a sign that the estrogen levels are rising. When this type of mucus is present, egg development has begun and unprotected intercourse is no longer safe.

A few days just before actual ovulation, the body's high estrogen levels cause the mucus to become much more abundant. It now looks clear and feels thin, slippery, and very stretchy and has the consistency of raw egg white. Some women can take a bit of it and stretch it between thumb and forefinger into a thin strand of 2 to 3 inches or more. This stretchability is called spinnbarkeit and is characteristic of this time of the cycle. Spinnbarkeit mucus is also called fertile-type mucus because it helps sperm to survive and reach the egg. Its presence is a sign that ovulation is about to take place. Many women are aware of this mucus as a wet feeling at the mouth of the vagina.

The estrogen spurt that triggers the production of fertile-type mucus typically begins several days before ovulation. The last day that this type of mucus can be felt is the day of peak fertility, when the ovary releases an egg. However, the only definite way to know that peak fertility and ovulation have occurred is 3 or 4 days afterward, when the mucus is definitely back to being sticky and skimpy.

From the fourth day after the peak day until the end of the monthly cycle, when you menstruate again, you are infertile. During this infertile phase, you usually will have little mucus for 7 to 12 days. A few days before your period begins, however, it may become a bit more abundant.

This description of the cervical mucus cycle may be true for many women, but not for all. You will not be able to use this method effectively until you understand your individual pattern. For the first month, you must record your mucus quality every day. And you must note the days when there is no mucus. Many women can see their pattern after one month, while others need more time and help from their health care provider or family planning instructor. Many fertility awareness counselors suggest complete abstinence from sex during the first cycle being charted, in order to avoid confusing the mucus with semen or normal sexual lubrication. With


Ovulation can be delayed if anxiety, stress, illness, or a change in your life occurs after your last menstrual period and before ovulation. If you then have a peak day that does not seem normal, during the following three days carefully check the characteristics of your mucus. Fertile mucus may reappear, indicating that ovulation was delayed and now at last is taking place. If it is not clear that the peak occurred and the infertile period started, postpone sex or use a barrier method.

experience, most women learn to tell the difference between these secretions.

When using this method, remember that douching is likely to wash out any mucus and a lubricant or spermicidal jelly could be confused with mucus. If you have a discharge from an infection, postpone mucus charting until it is cleared up. When you begin keeping a record, touch the mouth of your vagina every day to check for mucus and make a brief note of what you find—what it feels and looks like and whether it is skimpy or abundant. Also write down any other physical signs that may indicate a change in your fertility cycle.

During the infertile phase, the cervix is lower in the vagina and easier to reach. It feels firm to the touch and the os is closed. As ovulation approaches, the cervix withdraws higher in the vaginal canal and feels broader and softer. The os also begins to dilate so that you can actually feel the opening. Look for and record these changes. Other signs of ovulation are a pain on either side of the abdomen (known as mittelschmerz), breast tenderness, feelings of heaviness, or abdominal swelling. After ovulation, the cervix is again low in the vagina and feels firm and closed. Even though you may have no mucus at all at this time, you should be able to detect the other cervical changes that offer clues to your fertility pattern.

Although the mucus method alone can be an adequate guide, some health care practitioners recommend that it be combined with the temperature method for greater effectiveness. A great deal depends on the clarity of your record of mucus changes and on your


Women who absolutely must not get pregnant because of serious medical problems that would be worsened by pregnancy—and who would not have an abortion—are not good candidates. They are better served by a contraceptive that has an extremely reliable high rate of effectiveness.

Couples who find it difficult to refrain from vaginal intercourse for a number of days also are not good candidates, especially if they do not use barrier methods. Finally, women who are poor sleepers or travel a great deal cannot use the temperature method effectively, because lack of sleep and jet lag can affect the BBT.

temperature charts. When several months of experience with both methods demonstrate that the cervical mucus method is an accurate indicator of ovulation, you may feel comfortable using it alone.

The mucus method alone sometimes has uncertainties. As we mentioned, it can be difficult to distinguish between cervical mucus and normal vaginal secretions or a discharge caused by a vaginal infection. And it takes some practice to be able to tell the difference between mucus and vaginal medications, semen, or the lubrication that follows sexual arousal.

The mucus method does have several advantages over the other fertility awareness techniques. It does not require taking the basal body temperature every day. For women with very irregular periods, it requires fewer days of abstinence. And it is more effective than the calendar rhythm method.

Symptothermal Method

Because using any one method of fertility awareness alone may not be foolproof, many counselors recommend the symptothermal method, which combines checking your cervical mucus, recording your BBT, and watching for the other signs of ovulation. The symptothermal approach is particularly useful if you tend to have unusually long or short cycles, because the combination of methods helps to pinpoint your fertile phase.

You can record your BBT, mucus, and calendar information on the same chart. When using the symptothermal method, it is important to remember that the safe, infertile period begins: after 3 days of a consistent rise in BBT; after 3 days of having a closed, firm, low cervix; and on the fourth day after the peak mucus day. Both the mucus change and the temperature rise must occur before unprotected intercourse can be resumed safely. Changes in the cervix are used only to verify the other events.

It is a good idea to record the onset of your period, your daily BBT, your type of mucus, and your other signs until you are certain you know when you ovulate. From that point you can use only one method, if you wish.


Since cycle-based birth control methods (especially when combined with abstinence) can be difficult regimens to follow at first, it is strongly recommended that couples—or women—join support groups, women's health networks, or family life programs that offer classes in such methods. Personal feedback and support from other users of these methods are very helpful, especially during your first months of learning about cycles. Many churches and church-run hospitals offer family life programs and support groups. You need not be a church member to participate.

In many cities, the Catholic archdiocese has family life programs that teach natural family planning. A parish priest or teachers in local Catholic schools may be helpful in finding the nearest family life program. Many Planned Parenthood clinics or women's health centers also may have someone who is certified to teach the cycle-based methods.

Church-sponsored programs discourage the use of barrier contraceptives during fertile days but are good sources of education in the basics of natural methods. Your decision to use a condom, diaphragm, or cervical cap can be a private one. If your local women's health center or Planned Parenthood clinic teaches cycle-based methods, it is most likely to teach fertility awareness plus the use of any barrier method you choose.

If you have no local source on how to find instruction in cycle-based methods, you can write the Natural Family Planning Program, National Conference of Catholic Bishops, 3211 Fourth St. N.E., Washington, D.C., 20017, for information on the classes nearest you. The Program's telephone is 202-541-3240; its fax number is 202-541-3203.

Remember that it is important to find a teacher who has been certified by a school of natural family planning. Much of the effectiveness of these methods depends on how competently they are taught.


Cycle-based methods are inexpensive. There may be a small fee for the classes and you may need to buy record-keeping charts and a thermometer if you use the temperature or symptothermal method.

Pregnancy Guide

Pregnancy Guide

A Beginner's Guide to Healthy Pregnancy. If you suspect, or know, that you are pregnant, we ho pe you have already visited your doctor. Presuming that you have confirmed your suspicions and that this is your first child, or that you wish to take better care of yourself d uring pregnancy than you did during your other pregnancies; you have come to the right place.

Get My Free Ebook

Post a comment