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    Fertility Awareness

    Fertility awareness is a way to check the changes your body goes through during your menstrual cycle camera.gif. (It is also called natural family planning or periodic abstinence.) Learning about these changes can help you know when you ovulate. You can then time sexual intercourse to try to become pregnant or to try to avoid pregnancy.

    A woman is most often able to get pregnant for about 6 days each month. This includes the day of ovulation and the 5 days before it. On average, ovulation occurs 12 to 16 days before the menstrual period begins. So ovulation would occur on about day 10 of a 24-day menstrual cycle, day 14 of a 28-day cycle, and day 21 of a 35-day cycle. Sperm can live for 3 to 5 days in a woman's reproductive tract. So it is possible to become pregnant if you have sex 2 to 3 days before you ovulate.

    For fertility awareness to be used as birth control, either you must not have sex or you must use a barrier method of birth control for 8 to 16 days of every menstrual cycle. Barrier methods include diaphragms and condoms. So you must prepare each month, be familiar with your body changes, and talk with your partner about your cycle.

    Fertility awareness is not the best method of birth control to prevent a pregnancy. The number of unplanned pregnancies is 24 out of 100 women who typically use fertility awareness. But this method can be very helpful to time when to have sex to become pregnant.

    There are several basic methods to find the time of ovulation. For fertility awareness to work best, you need to use all of these methods together. Check your body changes using these methods for several months before using them to avoid pregnancy.


    • Calendar (rhythm) method. For this method, you guess your next ovulation time after recording your last few months of menstrual cycles. From the record, you guess which days of the month you are most likely to ovulate (be fertile). Your fertile days start 5 days before ovulation and end on the day of ovulation. This method works if your menstrual cycle is regular. If you are regular, you will ovulate on a certain day of the month. But very few women have regular 28-day cycles. Even women who have regular cycles can have irregular periods from time to time. Also, a woman does not always ovulate right in the middle of her cycle. She may be more likely to ovulate between 9 and 17 days before her next period. So the calendar method alone is not the best method of guessing when you might be ovulating.
    • Standard days method (SDM). This method works best for women who have cycles between 26 and 32 days long. Women who use this method usually use a special colored string of beads (CycleBeads) to keep track of their cycle.
    • Basal body temperature (BBT) method. Basal body temperature (BBT) is the lowest body temperature a healthy person has during the day. A woman's hormone levels during her menstrual cycle cause her BBT to fall 1 to 2 days before she ovulates. It will then rise a day or two after she ovulates. If you carefully measure and write down your BBT every morning before you get out of bed, you may be able to guess the day you will ovulate. Use a tracking chart with either Fahrenheit temperatures(What is a PDF document?) or Celsius temperatures(What is a PDF document?) to keep track of your temperature for a few months.
    • Cervical mucus method (Billings method). The amount, texture, and look of mucus made by your cervix camera.gif changes during your menstrual cycle. If you watch, feel, and write down this information for several cycles, you may be able to guess when you will ovulate.
      • Right after your menstrual period, you will not have much cervical mucus. It will be thick, cloudy, and sticky.
      • Just before and during ovulation, you will have more cervical mucus. It will be thin, clear, and stringy.
    • Hormone monitoring. Home ovulation kits can be used to help you learn the most fertile days of your menstrual cycle. These tests check the level of luteinizing hormone (LH) in your urine. You use a dipstick or test strip to measure the hormone. You dip the stick or strip into your urine and read the level on the strip. Or you may put the strip in a small computer unit that shows the level of LH. The computer can tell you when your most fertile days are.
    • Combined (symptothermal) method. This method uses some of the other methods all at once to tell you the most fertile days of your cycle. You check your basal body temperature, the changes in your cervical mucus, and a hormone test. You also watch for signs of ovulation. (These include breast tenderness, belly pain, and mood changes.) The physical signs of ovulation help you learn when you ovulate.
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    WebMD Medical Reference from Healthwise

    Last Updated: May 22, 2015
    This information is not intended to replace the advice of a doctor. Healthwise disclaims any liability for the decisions you make based on this information.

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