Women are most fertile during ovulation, according to the American Pregnancy Association. To predict ovulation, women utilize various methods such as ovulation predictor kits, ovulation microscopes and electronic fertility monitors. Women can also predict fertility by documenting their cycles and their bodies' response to increasing levels of estrogen.
Ovulation predictor kits are used to measure the level of luteinizing hormone found in women's urine, explains the American Pregnancy Association. These kits are used to look for the surge in luteinizing hormone that occurs 12 to 36 hours before ovulation. Another type of fertility monitor is an ovulation microscope. Ovulation microscopes are used to look at visual changes in saliva. When placed under the microscope, the saliva of a fertile woman takes on a fern-like pattern from the estrogen surge that occurs before ovulation. However, the most accurate type of fertility predictor is the electronic fertility monitor. With an electronic fertility monitor, an oral sensor and a vaginal sensor are used to measure electrolyte levels.
Although these tools can help women predict fertility, paying close attention to the menstrual cycle is also another method for determining fertility, notes Parenting magazine. Editors of the magazine suggest keeping track of the menstrual cycle for eight or more months to gauge fertility based on an estimated date of ovulation. Because this method allows for a rather large ovulation window, they also recommend measuring the basal body temperature, which is another indicator of ovulation.