How to take your Basal Body Temperature (BBT)
1. Taking Your BBT Temperature
Your Basal Body Temperature is probably best taken orally (simplest in my opinion ), by placing the thermometer under your tongue. BBT temperature refers to a resting or base temperature. That means that your BBT must be measured before activity, after at least four hours of sleep. Take your BBT temperature first thing each morning (ideally at the same time each morning) - as soon as you wake up and before you get out of bed or have a cup of tea! Other things such as hot drinks, infections, illness etc can affect your BBT reading.
2. Charting Your BBT Temperature
Starting on day one of your menstrual cycle – the first day of your period – begin recording your BBT temperature using graph paper. Each morning, record your temperature. Plot each days BBT on the a graph. Your temperature rise may be sudden, gradual, or in steps. The pattern may vary from cycle to cycle.
3. Predicting Ovulation
Typically a rise of at least 0.4 to 0.6 degrees centigrade or will take place at ovulation, though for different women the temperature increases may be sudden or gradual. Over time, charting you BBT will help you predict ovulation.
It is important to remember that the rise in your BBT (basal body temperature) does not tell you when you are most fertile or about to ovulate. It tells you when you already have ovulated. Women are most fertile in the few days before their peak temperature.