Tracking ovulation by monitoring your basal body temperature is one of the best ways to keep tabs on your ovulation at home. We recommend our female patients monitor basal body temperature by measuring and recording body temperature each day to identify the pattern of their cycle.[1]
We prefer this method because it provides our team and patients with a wealth of insight into their unique menstrual cycle. We recommend using the free Fertility Friend app with your tracking because it is simple and educational.[2]
Understanding your unique cycle lets you know when you are the most fertile. In turn, this gives you the most control over your conception attempts.
Moreover, understanding a woman’s unmistakable signs of fertility is one of the tools we teach every single one of our patients. It lets us know where we need to focus our efforts to ensure our patients get the result they are after – their healthy babies.
How does basal body temperature predict ovulation?
Basal body temperature (BBT) refers to your body temperature at rest. When you are ovulating, there will be a slight increase in your BBT. Take note that it is also affected by certain factors such as the following:
- Illness or fever
- Stress
- Shift work
- Interrupted sleep cycles or oversleeping
- Alcohol
- Travel and time zone differences
- Gynecologic disorders
- Certain medications
Despite these challenges, obtaining valuable data from your BBT is still possible by knowing these factors and precisely noting them in your chart.
By recording your BBT daily, you would get a pattern to help you identify and track ovulation signals. With temperature typically, the pattern zig-zags about, which is not particularly useful over one month — but over several months, clear patterns could emerge.[3]
Typically in the first half of the cycle, temperatures will rise and fall randomly — yet within a few points of a degree. Around mid-cycle, your temperature may dip slightly lower before rising and staying elevated. That dip and the following rise indicate that ovulation has occurred, although the drop is not essential for ovulation.[2-4]
The reason for the temperature rise is that the level of the hormone progesterone rises after an egg cell is released. This hormone is responsible for raising body temperature. Consequently, it drops when the egg cell is not fertilized.
Charting basal body temperature for tracking ovulation
Regarding accurate temperature readings, around 97.34°F (36.3°C) is where you want the temperatures to be during the first half of the cycle, rising to around 98.24°F (36.8°C), which is the textbook range of normal.[5]
The great thing about tracking BBT is that it can give us valuable information about your cycle and any hormonal imbalances we need to identify and correct.
Usually, after a couple of months, you start to develop a more defined understanding of your ovulation pattern. It is a great way to know your menstrual cycle and understand how it works and what needs improvement.[6]
However, note that this method by itself is not an accurate prediction of ovulation, but when used in combination with other tools, it plays a role. It should be noted that the interpretation of cervical mucus is the best way to predict when ovulation occurs or is about to happen.[7] When it becomes egg white-like and stretchy, you know that ovulation is approaching, and you can cue your partner to get started on babymaking.[8,9]
A key point to remember: Ovulation is not fixed. It may seem like clockwork for some people, but many women experience changes from month to month. At the same time, the difference in cycles from one woman to the next could vary dramatically. However, with consistent tracking of BBT and cervical mucus changes over time, you will start to identify patterns that provide great insight into when ovulation happens.[10]
How to track basal body temperature for ovulation?
To utilize the basal body temperature method for your conception attempts, follow these steps:
- When you first wake up, try to move as little as possible before taking your BBT every morning before leaving the bed.
- Plot your temperature readings on a fertility app or even just on graph paper.
- Plan sex carefully during your fertile days.
It is preferable to use a basal thermometer specifically designed to measure BBT, which shows you the temperature in tenths of a degree (allowing you to observe the slightest changes in body heat). However, if not accessible, just use a regular digital thermometer to two decimal places.
Ensure you have at least three hours of uninterrupted sleep each night for an accurate reading. Try and take your temperature around the same time every day. Do not do anything before you do so — even moving around. For best results, we recommend placing the thermometer directly under your tongue and waiting for the beep, although it is also fine to take it vaginally or rectally. Whatever you choose, just use the same method daily for the most precise results consistently.
Jot down your daily BBT, then look for a distinct pattern afterward. Once again, it may slightly increase when you ovulate — typically less than a 1/2 ºF (0.3 ºC). You could assume that ovulation has occurred when the slightly higher temperature remains steady for three days or more.
After charting your basal body temperature, monitoring your cervical mucus, and knowing your fertile days through patterns, you can move on to the last step – planning your conception attempts at your most fertile time.
You are most fertile about two days before your BBT rises, but sperm can live up to five days in your reproductive tract. If you are hoping to get pregnant, this is the time to have sex. If you are hoping to avoid pregnancy, unprotected sex is off-limits from the start of your menstrual period until 3-4 days after your BBT rises every month.
Final Thoughts
Knowing your unique fertility cycle is one area you can take charge of on your fertility journey. Using the BBT method in combination with checking your cervical mucus and using the information they demonstrate in your conception attempts ensures you are giving yourself the best possible chance of getting pregnant.
Understanding your fertility cycle is critical to fertility treatment success, so we have the Understanding Your Conception Cycle available to support you further. It is a 3-week program that helps couples better understand their conception cycle and their body’s fertile signs to optimize their chances of taking home a healthy baby. Click here for more details.
Why settle for an unexplained diagnosis?
Our results have been validated and presented in scientific forums such as Harvard University and The British Fertility Society.
References:
[1] Su, H-W., et al. Detection of ovulation, a review of currently available methods. Bioengineering and Translational Medicine, 2017. 2(3). PMID: 29313033.
[2] Fertility Friend. 2020. Retrieved from https://www.fertilityfriend.com/.
[3] Bull, J.R., et al. Real-world menstrual cycle characteristics of more than 600,000 menstrual cycles. NPJ Digital Medicine, 2019. 2. PMID: 31482137.
[4] Bedford, J.L., et al. Detecting evidence of luteal activity by least-squares quantitative basal temperature analysis against urinary progesterone metabolites and the effect of wake-time variability. European Journal of Obstetrics, Gynecology and Reproductive Biology, 2009. 146(1). PMID: 19552997.
[5] Simić, N., et al. Changes in basal body temperature and simple reaction times during the menstrual cycle. Archives of Industrial Hygiene and Toxicology, 2013. 64(1). PMID: 23585200.
[6] Charkoudian, N., et al. Reproductive hormone influences on thermoregulation in women. Comprehensive Physiology, 2014. 4(2). PMID: 24715568.
[7] Vigil, P., et al. Ovulation, a sign of health. The Linacre Quarterly, 2017. 84(4). PMID: 29255329.
[8] Symul, L., et al. Assessment of menstrual health status and evolution through mobile apps for fertility awareness. NPJ Digital Medicine, 2019. 2. PMID: 31341953.
[9] Han, L., et al. Cervical mucus and contraception: what we know and what we don’t. Contraception, 2017. 96(5). PMID: 28801053.
[10] Reed, B.G., et al. The Normal Menstrual Cycle and the Control of Ovulation. Endotext. PMID: 25905282.
