About Basal Body Temperature

Many women find that tracking their basal body temperature can help them get pregnant faster by determining their most fertile days. But how do you know what to look for? Read on to learn more about basal body temperatures and pregnancy.

Identification

Your basal body temperature, or BBT, is your body's lowest temperature of the day. Because your core temperature increases as soon as you stir from rest, your BBT should be measured in the morning, before you get out of bed. You need a special thermometer to measure basal body temperature. Most thermometers only read temperature to one decimal point; however, a basal thermometer will generally go to two.

Significance

Your BBT tells you more than an ordinary temperature measurement. Subtle variations in your basal temperature can tell you where you are in your menstrual cycle. Many women use this method to determine when they are ovulating, and also whether or not they are pregnant. After a few months of taking daily BBT measurements, you can determine your most fertile days.

Time Frame

Like many women, your menstrual cycle may not be 28 days long every month. Using a BBT chart can help you determine what cycle day you ovulate on, and when to expect your next period. Begin taking your temperature first thing in the morning on day 1 of your cycle. Until you ovulate, your BBT should not fluctuate more than a few tenths of a degree from this number. Once your temperature spikes, it will be half a degree to a whole degree higher than your baseline. Your BBT should remain close to this new number for the next 14 days. The exceptions to this are if your luteal phase, or the time frame between ovulation and your period, is not the usual 14 days long, or if you are pregnant. Once your temperature drops back to the baseline, you will start your next period, and can begin tracking your next month's BBTs.

Warning

Tracking BBT is only one of many ways to predict your fertile times. Often, by the time your temperature indicates that you have ovulated, you have already missed most of your fertile days. Also, if your cycles or your luteal phase vary in length from month to month, tracking BBT may not be enough to determine when your chances of conceiving are the greatest. On the other hand, if you are using BBT charting as a form of birth control, you may not find out you are in your fertile time for a few days, during which you may become pregnant.

Considerations

While keeping track of your basal body temperature is a great way to determine what is going on in your menstrual cycle, it may not be enough. BBTs are best combined with other forms of fertility prediction, such as cervical mucous consistency or ovulation prediction kits. Using more than one approach to determine your fertile days can help you get pregnant faster than using BBT alone.