The rhythm method is a biological birth control technique that does not require any special apparatus or medication. It does involve some careful planning and must be followed exactly to be effective. The essence of the rhythm, or calendar, method is to identify the days on which a particular women is potentially fertile or infertile and then engage or avoid sex based on family-planning goals. Traditionally, the method consisted entirely of measuring the duration previous cycles. Because many women have occasional irregularities in their cycles, the modern natural family-planning approach includes additional techniques to identify ovulation.
Step 1
Measure the duration of your cycle. For at least two months--but ideally a year--prior to implementing the rhythm method, keep careful records of your menstruation. The first and last days of menstruation are of particular importance for calculating fertility. One full menstrual cycle is from the first day of menstruation until the next first day of menstruation. Accurate record-keeping will allow you to determine the regularity of your cycle.
Step 2
Calculate your approximate infertile period. Subtract 19 from the number of days in your shortest cycle to find the duration of your pre-ovulatory infertile period. Subtract 10 from the length of your longest cycle to find the start of the post-ovulatory infertile phase. For example, if your cycle ranges from 28 to 32 days from the start of one menstruation to the next, you would be infertile for roughly the first nine days after the start of menstruation--28-19=9--be fertile from day 10 to 21, and resume infertility on day 22--32-10=22.
Step 3
Locate your ovulation window. Subtract 14 days from the first date of menstruation in your shortest cycle to locate the expected date of ovulation. Generally, ovulation will occur plus or minus two days from the expected date, plus any amount of normal variation in the total duration of your cycle. Ovulation marks the high point of fertility in the menstruation cycle, and sexual intercourse should be avoided for more than three days--the lifespan of a sperm cell--before and after ovulation to prevent pregnancy.
Step 4
Observe cervical mucus and shape. While you are compiling data on your menstruation cycle, observe changes in your cervical mucus. According to Familydoctor.org, when you are approaching ovulation, the mucus will become clear and slick like raw egg white. The shape or position of your cervix may also fluctuate predictably during different phases of your cycle. The U.S. Council of Catholic Bishops recommends awareness of changes in your cervix as a way to vastly improve the accuracy of the rhythm method by helping you locate ovulation with more precision.
Step 5
Take your basal body temperature. Prior to implementing the rhythm method and while it's in use, the Palo Alto Medical Foundation recommends taking your temperature first thing when you wake up and before doing any strenuous activity. The basal body temperature--the lowest temperature reached by your body--is another indicator of ovulation since heightened levels of progesterone at ovulation raise your body temperature.
Tips and Warnings
- The rhythm method is not 100 percent effective, but the more effort you put into knowing your body and its rhythms the better you will be able to predict your periods of fertility and infertility. The Palo Alto Medical Foundation suggests that by supplementing the traditional rhythm method with more precise observations that help you identify ovulation, you can exercise control over family-planning choices without using contraceptives. However, one useful application of the rhythm method noted by Contracept.org is simply to identify days when it's most safe to forgo barrier methods of contraception--such as a condom--and when it's not.
- The rhythm method is not recommended for women with very irregular menstrual cycles that cannot be easily predicted. Different groups have applied different terms to this natural form of birth control, including natural family planning and the standard days method. With the same basic goal of identifying a women's periods of fertility; however, these are all methods designed to build upon and improve the accuracy of the traditional rhythm method.
