bbt charting

Basal Body Temperature

"Fertility charting allows you to predict ovulation, pinpoint your most fertile time in your cycle and increase your chances of becoming pregnant... BBT charting is the cornerstone of your fertility chart..."

Measuring and recording your basal body temperature and charting the temperature changes on a graph will help pinpoint when ovulation takes place during your menstrual cycle and help you predict fertility based on chart trends.

Because basal body temperature charting (bbt charting) allows you to verify the when ovulation takes place, it is a highly instructive method to increase the likelihood of conception each month. It also helps you understand the overall patterns of your menstrual cycle.

For most women, during the first 2 weeks of your cycle, your resting body temperature is relatively low (97.0 to 97.5 F). This is due to the presence of estrogen.

At ovulation, a rise in body temperature takes place - caused by an increase of the hormone progesterone - in order to provide a warmer, more fertile environment in the womb. A minimum temperature increase of 0.4 to 0.6 degrees F may be detectable - and this measurable change will last through the rest of your cycle. By monitoring when this temperature change takes place (temperature spike) you can very closely determine when ovulation occurs each month. Over time, the patterns on your fertility chart will tell you when ovulation will occur - so your chart will perform a key predictive function!

Your basal body temperature can be taken with a special basal thermometer. A thermometer that registers from 96 to 100 degrees (in easy-to-read one-tenth degree increments) is ideal. Digital thermometers are available - and they do NOT contain mercury - a safe choice for health-conscious mothers. Fairhaven Health offers two basal thermometers: The digital basal and a new non-mercury glass basal thermometer for traditionalists who prefer glass thermometers.

Your basal temperature refers to a 'resting' or 'base' (basal) temperature. That means that your BBT must be taken prior to any physical activity, and after at least three to four hours of sleep. Make sure that you read thermometer directions - and if you have any questions or unique considerations, consult your physician. Take you temperature before you even get out of bed!

1. Taking Your Basal BBT Temperature
Take your BBT first thing each day - as soon as you wake up. It is recommended that you stay in bed (as any movement can increase your resting temperature). That means going to the bathroom should wait, if possible! In addition, avoid eating or drinking. Insert the thermometer in your mouth and wait five minutes or until your digital beeps. Read the temperature to within 1/10 of a degree and record the temp on your fertility chart.

2. Charting Your Basal Temperature
Starting on day 1 of your menstrual cycle - the first day of your period/bleeding - begin recording your basal temperature using a special ovulation calendar or graph paper. Each day, record your bbt temperature. Plot each day's temp on the graph and draw a line to get a sense of movement (rising or falling lines on the graph). Your temperature spike may be sudden, gradual, or in steps and the pattern may vary from cycle to cycle. Most women do see a marked change, indicating ovulation.

3. Using Your Chart to Predict Ovulation
For most, 96 to 98 degrees is considered normal prior to ovulation and 97 to 99 degrees is typical after ovulation. By charting the daily differences in basal temps you can determine when ovulation has taken place. Typically a rise of at least 0.4 to 0.6 degrees will take place at ovulation, though for different women the temperature increases may be sudden or gradual. Over time, you should be able to see patterns in your cycle - days when you will be most fertile. Your fertility chart can be augmented with by charting other key natural fertility signs, including cervical mucous, position of cervix, various tests and monitors, and ovulatory pains.

See how your chart compares with our ovulation calendar