Calculating a woman's period is a painless process. Women actually have two periods within their cycle of ovulation. One is the menstrual period, which is when the woman's body is getting ready to produce an egg that could potentially be fertilized. During this time, the uterus prepares and sheds excess blood to get ready for the coming egg. A woman's fertile period is the other period. This period is the one in which a woman is most likely to get pregnant.
Calculate a woman's menstrual period cycle by merely counting days. A menstrual cycle occurs in most women between every 23 and 35 days, though most often it's right in the middle. The menstrual period can be predicted almost to the day if you keep in mind the day that her period began for several months in a row. This process is even easier if a woman is on birth control, as for many, birth control keeps a period occurring at nearly the same time every month.
Use a calendar to accurately calculate a woman's fertile period. The fertile period is the period in which a woman is most likely to get pregnant. There is basically a 24-hour window in which a woman is at a high risk of getting pregnant. Generally, an egg is released into the fallopian tubes 13 to 16 days after the period ends. To get pregnant, most women have to have sex the day before or the day that the egg is released for it to become fertilized. Sperm has to be in the fallopian tube in order to come in contact with the egg or it becomes infertile.
Visit your pharmacy and buy fertility prediction tests. Some people's fertile periods vary and these tests can be useful. Some tests measure body temperature, as when a woman is fertile, generally her body temperature rises, though it's unnoticeable. You can also take your temperature on your own, with your home thermometer. Other tests measure vaginal secretions; they vary slightly for most women when they are fertile.
Don't panic if you have trouble calculating your fertile period or even menstrual period. Some women are irregular frequently. However, if you are trying to prevent pregnancy, it's wise to use multiple methods of pregnancy prevention, as your fertile and menstrual period may be harder to accurately calculate.