BBT (Basal Body Temperature) Chart- Everything You Need To Know

5 min read

If you are trying to conceive, ovulation is one of the most significant factor to pay attention to. Ovulation takes place after the ovary releases a mature egg that is ready for fertilization into the Fallopian tube. It usually takes place in middle of your menstruation cycle but it does not hold true in all cases. With an irregular period, your ovulation can be delayed or you may fail to release an egg. In such cases, it can be extremely difficult to pinpoint exactly when ovulation takes place. To get pregnant, it is important to know when you ovulate so you can time sex appropriately. There are several ovulation predictor kits available in market, which are handy and helpful in determining ovulating time. But many women prefer to track their ovulation cycle by charting their basal body temperature (BBT). This is an inexpensive, low-tech way which helps to determine when you are ovulating. To understand more about BBT charting continue reading.
BBT Chart

What Is Basal Body Temperature?

Basal Body Temperature (BBT) is the lowest body temperature in a 24-hour period. It is the resting temperature and is usually taken immediately after waking up in the morning before you indulge in any physical activity. It is best to use a basal thermometer, which is very sensitive and is able to measure even the minutest changes in body temperature. In order to accurately measure the basal body temperature, it is recommended to wake up and take the temperature at same time every day.

How To Understand The Variations In Your BBT?

The body temperature of a woman drops slightly just before the ovary releases an egg. Then, 24 hours after the egg is released by the ovary, the temperature increases by 0.25 to 0.50 F and remains high until the next period takes place.
The hormone progesterone, secreted by the ovary after ovulation, is behind the slight rise in temperature. This happens as an after effect of progesterone preparing the body for pregnancy. The body temperature will remain about half a degree higher until right before next menstruation.
A woman generally has lower temperatures before ovulation, and higher temperatures afterward. This is known as a biphasic pattern. Making a chart of biphasic pattern by recording BBT readings help to determine the ovulating time.

How To Chart Basal Body Temperature?

First of all, let’s see what all is required before preparing the chart.

  • A digital thermometer, which detects even minutest changes in temperature
  • Keep a book or a graph book handy by your bed along with the basal thermometer. Make sure you do not move a lot to fetch it
  • Always try to take the temperature during the same time every day. Keep an alarm so that you wake up same time every day to record the temperature
  • You can take the temperature orally, vaginally or anally. What you have to bear in mind is that you should stick to a single method rather than switching on and off. Also, to get an accurate reading, make sure that you place the basal thermometer exactly the same way as you did it on the first day
  • Have a minimum of five hours of sleep before you take the basal body temperature

Now let us see how to chart the BBT. Start taking the temperature from the first morning after the period starts. Take care of the tips mentioned above. Now you can:

  • Use a fertility-tracking app to feed the temperature you measured. This app will instantly plot a graph based on the temperature you feed and even highlight the day when the temperature was highest to indicate ovulation
  • You can also manually record the reading and plot it on a graph which is either printed or drawn by you
How To Analyze The BBT Chart?

There are two phases in the chart (biphasic pattern). The first half represents follicular phase with low temperature and second half, the luteal phase, with increased temperature that remains raised until the end of the cycle.
The number of days in the follicular phase can be subjected to some variations in consecutive months but the luteal phase remains constant (14 days) in most cases. Once the luteal phase falls below 10 days it is always advisable to consult the gynecologist, as it can be an indication of some underlying problem that is preventing you to conceive.
Once there is a slight rise in body temperature, it means that you are ovulating and in order to increase your chances of getting pregnant, you need to have intercourse now. When your basal body temperature is at its highest then it is the most fertile day. The few days before this particular day will also be some of your most fertile days. Charting for a few consecutive months will help you to predict a pattern of ovulation thus helping you plan your pregnancy accordingly. It will assist you to recognize your most fertile days in which you are most likely to conceive.

What Are The Benefits Of BBT Charting?

Once you start charting your BBT and if everything is normal with you and your partner, then you can get pregnant within 4 to 6 cycles. This because charting helps you to know when you are ovulating thus allows you to have sex during your fertile times. The chart also lets you identify your normal cycle. When using a chart, it is easy to find your normal ovulatory pattern. In addition to help you get pregnant, BBT charting can also alerts you to some possible complications, which includes:

  • Anovulation: If there is no rise in temperature in few consecutive charts, then there is a possibility that ovulation is not taking place. Keeping a BBT chart, alerts you so you can consult your doctor and look into the problem
  • Luteal phase defect: As mentioned earlier, an ideal luteal phase is 14 days. A luteal phase which is shorter than 10 days can make it difficult to conceive, as the fertilized egg will have difficulty in implanting in the uterus. You can easily notice if your luteal phase is short if you see the lack of 10 high temperatures on your BBT chart
  • Thyroid condition: Hyperthyroidism and hypothyroidism can cause problems in conceiving. If you have very low temperatures, a less active thyroid gland can be the culprit. Similarly having abnormally high temperatures can be related to over active thyroid gland
  • Male factor infertility: There are chances that there are fertility issues with your partner even if you are constantly having sex on your fertile days but failing to get pregnant. BBT charting can bring this problem to your notice and thus help you to take medical help
What Are The Drawbacks Of BBT Charting?

Although many women prefer charting their BBT but it isn’t foolproof. For some women a clear pattern of temperature may not be visible. It is a myth that every woman ovulates on day 14 of her cycle. In some women a normal pattern of ovulation can mean ovulating on day 10 or day 21. So BBT charting cannot predict ovulation in advance, it can only tell when you are ovulating.
Also the chances of getting pregnant are highest during the two days before ovulation and the day it happens. The basal body temperature will only show variations 12 to 24 hours after ovulation. The egg only lives for approximately 24 hours, so timing is key. But by the time BBT indicates the ovulation, the clock is already ticking and there will be very little time for fertilization of an egg by the sperm, thus bringing down the chances of pregnancy.
Another drawback of BBT charting is that it can be very complicated to interpret. There can be rise in body temperature due to other factors also like changes in weather patterns, what you ate the previous night etc.

Responses (0)

Please check a captcha

Want curated content sharply tailored for your exact stage of parenting?

Discover great local businesses around you for your kids.

Get regular updates, great recommendations and other right stuff at the right time.


Our site uses cookies to make your experience on this site even better. We hope you think that is sweet.