Record the number of days in each cycle, including the day you start your period. The last day of each cycle is the day before your next period starts. Keep tracking your cycle this way for eight to twelve cycles. The more cycles you have to reference, the more accurate the calendar method will be.
Alternatively, you can use an online ovulation calculator such as the WebMD Ovulation Calculator. Make sure all of the information described below is included in the calculation, or it may be a less effective prediction.
Predict the first fertile day in your current cycle by finding the shortest cycle in your chart. Subtract eighteen from the total number of days in that cycle to find your first fertile day, meaning the first day in your cycle when pregnancy could occur. For example, if your shortest cycle lasted 26 days, your first fertile day would be the 8th day in each cycle (26 - 18 = 8), counting the day you began your period as day one. Predict the last fertile day in your current cycle by finding the longest cycle in your chart. Subtract eleven days from the total number of days to find the last fertile day in your cycle. For example, if your longest cycle lasted 31 days, your last potentially fertile day in each cycle would be the 20th day in the cycle (31 - 11 = 20). Note that the more regular your cycle duration is, the more effective this method will be. [10] X Research source
Chart the days when you have your period, dry days, and days when your mucus is tacky, sticky, slippery, and wet. Note changes in color and smell in addition to texture. Note whether the mucus is cloudy or clear. Keep as thorough a record as possible, especially in the first few months when you’re still getting used to this method. Breastfeeding, infections, certain drugs, and other circumstances can affect the cervical mucus, so be sure to note these factors as well.
The most accurate readings are taken in the vagina or rectum, but there are also basal temperature thermometers designed to take readings in the mouth. Stick with the same method during the entire process, and try to measure at the same depth and angle each time.
The average woman’s body temperature is 96–98ºF (35. 6–36. 7ºC) before ovulation, and 97–99ºF (36. 1–37. 2ºC) after ovulation. If you get results significantly outside this range, consult the thermometer instructions to make sure you are using it correctly.
There is another type of testing kit, using which you can test your dried saliva under a microscope for “fern” patterns that sometimes indicate a rise in estrogen levels in the few days leading up to ovulation. [16] X Trustworthy Source US Food and Drug Administration U. S. government agency responsible for promoting public health Go to source This is less reliable than the LH test, especially if you have poor eyesight.
Ovulation tests accurately predict the level of LH in urine, but the surge in LH only lasts about 24–48 hours, giving you a short window to detect it. Using multiple methods to track ovulation is recommended. Some tests may work slightly differently, so check the instructions. For example, you may need to urinate into a cup and dip the test into it, or the fertility symbol may show up as a smiley face instead of a line. [19] X Research source
