If you’re trying to conceive, you might have heard people discussing how your typical temperature, specifically your basal body temperature (BBT), can be used as a tool to help you. If this is the case keep reading to find out what the basal body temperature method is, how it relates to conception, and what the scientists think of this method of helping you to conceive.
What is basal body temperature (BBT)?
Your basal body temperature (BBT) is your resting body temperature. Testing in the morning, when you have had enough sleep (after at least three consecutive hours of sleep), provides the most accurate results for BBT. Your BBT increases slightly after ovulation, making it possible to pinpoint your fertile window during ovulation.
Tracking your BBT allows you to predict when you ovulate, so you can be sure to schedule date night for the right time of the month, maximising your chance of conception.
Changes to basal body temperature after ovulation
During ovulation, the body releases a mature egg from the ovaries. Once this happens, your basal body temperature increases slightly, by 0.5 to 1 degree Fahrenheit (0.22 to 0.56 degree Celsius). This is a side effect of an increase in your hormone levels (progesterone) during this stage of your natural cycle. Your BBT will then stay high for the rest of your cycle.
Why should I test my basal body temperature?
There are two main benefits in monitoring your cycle:
- Effectively timing intercourse to increase the chance of conceiving.
To become pregnant, you need to be intimate at the right time of the month. Tracking your BBT for a couple of months will allow you to predict when you will next ovulate, allowing you to plan ahead - Understanding your natural cycles.
There are many factors to consider, but monitoring your cycles and paying attention to changes in your body will enable you to understand your menstrual cycle better. Not only does this allow you to spot the signs of ovulation more easily, but it also gives you a greater understanding of other symptoms connected with changes in your menstrual cycle, such as mood swings, desires and fatigue.
How do I measure or check my basal body temperature?
You should test your basal body temperature as soon as you wake up, and before you get out of bed. The best time to check is after three consecutive hours of sleep. When using the temperature method, consistency is crucial for accuracy, so make sure you use the same basal body thermometer and test at the same time each day.
What is a basal body temperature thermometer?
To measure temperature, a basal body temperature thermometer offers a more accurate reading than a typical home thermometer. A basal body temperature thermometer provides results to two decimal points, allowing for precise measurements that reveal slight fluctuations in temperature.
How to tell whether my basal body temperature is up or down?
The first time you measure your basal body temperature, there is no way of knowing whether it is up or down. That knowledge comes from repetition. To track changes, you need to establish a consistent understanding of your basal body temperature over a number of weeks.
To help you identify changes in your menstrual cycle, you should track your results on a graph. You can create a simple basal body temperature tracking chart yourself at home, using a simple line graph. Across the x-axis (horizontal), list the days of your cycle; the y-axis (vertical should represent the temperature.
Be sure to give each degree plenty of space on the graph (e.g., 97, 97.2, 97.4) so that you can see even the most minor temperature changes when charting BBT.
What happens if I forget to take my temperature?
If you forget to take your BBT in the morning, try not to worry. Although it might be more challenging to identify patterns with incomplete data, missing just one day might not make a significant difference. Keep tracking your BBT each morning.
Leave the BBT thermometer somewhere visible so you’ll see it as soon as you wake up and remember to take your temperature.
What is the ideal basal body temperature to get pregnant?
Many people want to know, ‘What is the most fertile BBT level?’ Unfortunately, there’s no ‘one size fits all’ temperature for conception when it comes to BBT. Tracking your BBT allows you to identify the basal body temperature rise that occurs after you ovulate.
The basal body temperature method highlights when ovulation has finished, not when it begins. Although this might be frustrating when you want to know whether you’re ovulating right now, it can help you predict ovulation, so you know when it’s likely to occur next month.
What is a normal basal body temperature when trying to conceive?
Your normal basal body temperature is unique to you. Taking a daily basal body temperature allows you to gain a clear picture of your body’s resting temperature, enabling you to identify temperature rises that indicate ovulation has occurred.
What should the basal body temperature be when ovulating?
If you’re only tracking BBT, ovulation day will be over by the time you notice a change in your temperature. For this reason, it’s worth combining BBT tracking with cervical mucus tracking.
Tracking your vaginal discharge allows you to pinpoint ovulation by paying attention to changes in your cervical mucus. Vaginal discharge is usually white and tacky, but changes to a clear, slippery egg-white consistency during the fertile period. Combining cervical mucus tracking with your BBT readings allows you to build a thorough understanding of your fertility.
To find out more about cervical mucus fertility tracking, see BellyBelly’s article Cervical Mucus And Ovulation | Identify Your Fertile Period.
How long will my BBT level stay high after ovulation?
How long your BBT level stays high after ovulation will depend on whether or not you’re pregnant. If you’re not pregnant, your BBT will decrease by the end of your current menstrual cycle. If you are pregnant, however, your BBT will stay high for longer.
When will my basal body temperature drop?
If you’re not pregnant, your BBT will drop a day or two before your next menstrual period. Knowing this can help you identify when your period is due, which can be helpful; however, it isn’t a fool proof method of accurately predicting the onset of your period.
What does BBT look like when pregnant?
Basal body temperature increases after ovulation, and usually stays high until the end of your cycle. Your basal body temperature typically decreases a day or two before your period begins. If you’re pregnant, however, your basal body temperature will stay high.
What should the basal body temperature be in early pregnancy?
If your period is late and your basal body temperature is still high, this could be an early sign of pregnancy but it isn’t an accurate way to detect pregnancy.
The best way to know whether or not you’re pregnant is to wait until the day your period is due and take a home pregnancy test. For accurate results, make sure you follow the instructions carefully.
Your basal body temperature chart, pregnant vs not pregnant
If you measure BBT and plot your results on a graph for a sustained period, you’ll be able to compare different cycles.
If you’re not pregnant, your BBT will drop again by the end of the luteal phase, so your numbers are back down to normal by the start of your next period. If you are pregnant, however, your temperature will stay elevated for longer.
What is the 3 over 6 rule in BBT?
The ‘3 over 6’ rule is a straightforward method for identifying ovulation using the basal body temperature method. Six days of low temperatures followed by three days of slightly higher temperatures indicate ovulation has occurred.
The reason you should wait until you have three days of higher readings is that your BBT can fluctuate from day to day, making it difficult to use one day’s readings accurately. Several things can affect your basal body temperature readings:
- Stress
- Poor sleep
- Illness
- Alcohol
- Certain medications
- Breastfeeding.
Basal body temperature as family planning
BBT tracking isn’t reliable enough to use as a contraceptive method. BBT tracking highlights the day after ovulation, which is problematic if you had unprotected sex the day before and don’t want to get pregnant.
A 2017 article published in Bioengineering and Translational Medicine found that BBT tracking was an unreliable method for determining ovulation.
Speak to your healthcare provider for advice about contraceptive methods and which method might be right for you.
What is a BBT dip in early pregnancy?
Some women claim a one day slight dip in BBT is a sign of implantation, but this hasn’t been scientifically proved. Unfortunately, there’s no way of accurately predicting whether you’re pregnant other than waiting to take a home pregnancy test at about the time your period is due.
