Introduction
The counting method of birth control, also known as the rhythm method, the calender method, fertility awareness or natural family planning, is the concept of avoiding sexual intercourse on days when the woman is most likely to become pregnant, or to use another form of birth control on those days, such as condoms. A woman is most likely to conceive on or around ovulation, so if she is able to determine when she ovulates, pregnancy may be avoided by abstaining from intercourse during that time of her cycle. The counting method is the only method of birth control condoned by the Catholic Church.
Determining Ovulation
Ovulation occurs approximately 14 days before menstruation begins. To get a rough idea of when you ovulate, count back 14 days from the start of your period. For example, if your cycle is consistently 28 days long, ovulation occurs around day 14. If your cycle is 30 days long, ovulation will occur around day 16. To use the counting method of birth control most efficiently, you must track your cycle for a minimum of one year to get an accurate average of how long your cycle is. Ovulation may also be tracked by taking your basal temperature daily or by tracking the consistency of your cervical mucus, which is thinner around the time of ovulation. Your basal temperature will rise 0.4 to 0.8 degrees Fahrenheit when you ovulate.
Avoiding Pregnancy
Once you have determined when you ovulate, the next step is planning sexual intercourse around that. The woman's egg is viable for only 12 to 24 hours after ovulation, but a man's sperm can remain viable in the woman's body for up to seven days. Therefore, if you are using the counting method of birth control, it is recommended that you avoid intercourse for several days before and after ovulation, or use another method of birth control to avoid pregnancy.
Drawbacks
Unlike condoms, the counting method offers no protection against sexually transmitted diseases.
Very few women have menstrual cycles consistent enough to use the rhythm method of birth control effectively. If your cycle is 24 days long one month and 32 days long the next, it can be extremely difficult to determine when you ovulate.
Some couples may find it hard to stick to a system of "safe" and "unsafe" days. Because the counting method of birth control has a failure rate of up to 25 percent, it is best used in conjunction with another form of birth control. The counting method requires making a commitment to track the woman's cycle over a long period of time, so it is best used in long-term relationships---particularly those where the couple is prepared to deal with a pregnancy if the counting method fails.
