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Calendar Birth Control Method
by Marcie Fitzmaurice
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Overview
Women who use the calendar birth control method as their chosen contraceptive to prevent pregnancy use their past menstrual cycles to predict when they will ovulate in the future. To use this method correctly, you need to keep a written account of several menstrual cycles, including such information as when your period started and ended. Through compilation of such information, you can determine when you are less likely to conceive.
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Required Cycles of Data
For the most accurate results and data, keep a record of at least eight menstrual cycles. Do not use hormonal contraception while keeping these records.
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Collecting Data
First, record the number of days in a menstrual cycle. Start from the first day of one period and count until the first day of the next period. Circle the day when there is the first detection of bleeding. Follow this procedure for eight menstrual cycles. Second, check through the data of cycles and find the record with the shortest cycle. Subtract 18 from the total number of days in the cycle. For example, if the shortest cycle was 27 days, then 27 -- 18 = 9. Third, for that cycle, start from the day that you circled and count ahead 9 days; mark it with an X. This is the first day you are likely to be fertile, and when either abstinence or a barrier method is needed to prevent pregnancy. Fourth, determine the last day likely to conceive by finding the longest cycle and subtract 11 from that number. For example, if the longest cycle is 30 days, then 30 -- 11 = 19. Again, starting from the circled day of the cycle you previously used, count ahead 19 days and draw an X. That's the last likely day for fertility. The days in between the two X's are the most likely days conception will occur, so abstinence or the use of a barrier method is required to prevent pregnancy during those days.
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Effectiveness Rate
Typically, there is an 87-percent effectiveness rate for women who use the calendar birth control method. For every 100 women who use this method for one year, 87 of them won't become pregnant while 13 of them will. For women with menstrual cycles that vary in length or occurrence, the calendar birth control method is not dependable for the prevention of pregnancy.
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Advantages
There is no cost to using this method of contraception. Classes may be offered to teach this method, and that cost varies depending on location.
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Disadvantages
In order to get a good understanding of their menstrual cycles, women need to monitor and keep accurate records of cycles. During the times a woman is fertile, she will need to either abstain from sex or use a barrier method of contraception. Also, the calendar method does not prevent against sexually transmitted diseases.
