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Charting Your Basal Body Temperature (BBT)

By Asvini Prakash

The Basal Body Temperature of a person is the temperature of the person at rest. During ovulation, the BBT of a female will rise slightly. This variation can be noted monthly to determine when you are ovulating. Keeping a chart of your BBT over time can help you to gauge when you are most and least likely to get pregnant and is a great natural family planning method.

The day of ovulation and 5 days before is the best time to get pregnant.
Before ovulation, the BBT of a woman averages between 36.1°C (97°F) and 36.4°C (97.5°F). After ovulation, or about 24 hours after an egg is released, the BBT increases to 36.4°C (97.5°F) to 37°C (98.6°F). The most fertile period comprises the days before the rise in temperature. It is recommended that you maintain a charted record of BBT temperature, and other ovulatory changes for at least 3 months to obtain the information necessary to determine the approximate day of ovulation during a regular menstrual cycle.

BBT can also be tracked to avoid getting pregnant. If you are not planning to get pregnant, you should avoid having unprotected intercourse from the start of menstruation until 3 or 4 days after the rise in BBT. To effectively prevent pregnancy, you should combine it with other fertility awareness-based methods, such as the cervical mucus method. This method is based on the theory that cervical secretions change immediately before ovulation. Using these two approaches in combination is known as the symptothermal method.

The Nabta Cycle App can be used to record the Basal Body Temperature and store the data. It is important to take your temperature at the same time every day. First thing in the morning, before you get out of bed is a good time, as your body should be at rest after a night’s sleep. 



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