Basal Body Temperature? What is Ovulation Temperature?

When you start your pregnancy journey, an entirely new vocabulary comes into play. Suddenly, websites, baby books, and doctors are talking to you about things like “follicular phases,” “luteinizing hormones,” and “basal body temperature.”   

While you might feel a little like you’re back in high school biology class, learning the language of your reproductive cycle can help you start your pregnancy journey on the right foot and create a successful path to conception. 

In this guide, we’ll discuss basal body temperature in particular and how knowing what it means and tracking it can help you conceive.

What is basal body temperature? 

During our waking hours, we typically expect our body temperature to hover around 98.6 degrees Fahrenheit. It’s a standard that was set way back in the 19th century, and probably what your mother looked for when she was checking you for a fever. But these days, we regard a normal body temperature as ranging between 98.2 to 98.6 degrees Fahrenheit. 

Our basal body temperature (BBT), on the other hand, refers to a number below this range. Basically, BBT is the lowest healthy temperature the body can achieve while in a state of rest. It averages between 97 and 97.5 degrees Fahrenheit in women and is most commonly observed during or just after sleep.

When you’re ovulating, your basal temperature spikes. Occurring in the luteal phase of the menstrual cycle, the spike can be as subtle as 1/10th of a degree—between 97.6 and 98.6 degrees Fahrenheit—but that fraction makes all the difference. This heightened BBT temperature is now referred to as your ovulation temperature. 

Why does BBT spike during ovulation? 

This uptick in temperature is a result of the fluctuation of the hormones that govern your monthly menstrual cycle. Not sure of how your hormones ebb and flow every month? 

Essentially, before ovulation, your hormones surge. These hormones include:

• Estrogen – Which becomes the most high-profile hormone in your body, prepping your reproductive system for its next phase (ovulation, aka the release of your egg).
• Luteinizing hormone (LH) – Which assists in the egg’s growth and release.
• Progesterone – Which triggers the egg’s release from the follicle and increases your BBT. Progesterone is also the hormone responsible for the suite of less-than-pleasant symptoms known as PMS (thanks, progesterone!).

This temperature rise in your BBT and your resulting ovulation temperature doesn’t taper off until menses begins, after which, your BBT will be restored to business as usual.

How can BBT help you determine when you’re ovulating? 

If you’re trying to conceive, getting acquainted with your basal body temperature is an effective way to gauge when you’re most fertile and increase the potential for getting pregnant. This is also known as the “temperature method.”

Because a spike in BBT is an indicator of upcoming ovulation, tracking your BBT can help:

• Determine your ovulation window
• Pinpoint your ovulation day

In using the basal body temperature method, you can identify the window when you’re most likely to conceive. Let’s nail down exactly how to use the BBT method to assess this. 

How To Take Your Basal Body Temperature 

First things first: because a temperature change in BBT can be tiny (down to 1/10 of a degree!), your best bet is to get a basal thermometer, specifically designed to detect BBT.

Next, decide what method you’ll use to log your daily temperatures. There are a host of apps designed to record and visually chart the changes of your cycle (such as Period Tracker, Clue, and Flo), but if you prefer to kick it old school, you can go analog and print a fertility calendar template for easy visualization.

Once these tools are on hand, begin your BBT charting to get in touch with your ovulation cycle. Here are a few helpful tips:

• Commit to a daily wake-up call – Try setting your alarm about a half-hour or 45 minutes before you normally rouse naturally. Since BBT is most observable during sleep or just rising from sleep, take your BBT right away. Don’t even bother to get out of bed! Consistency is key for getting the most accurate picture of your BBT, so try to stay committed to your new wake-up call once you’ve established it.
• Track for at least 3 months – While you’ll begin to get a sense of your BBT by your first cycle, you’ll have the most reliable BBT chart after at least 3 months of tracking. 
• Use the same thermometer – Make sure to use the same thermometer for your recordings since individual devices can be finicky.
• Ensure you’ve slept enough – Your body needs to have a solid 4 hours of sleep for BBT to level off to its natural baseline. This means if you were tossing and turning (or got up to pee) at 4am, a 7am wake-up call may not accurately reflect your baseline temperature. Since you’ll be tracking your BBT for at least 3 months, a couple of restless nights won’t impact your overall results. However, if you’re consistently experiencing poor sleep, it’s best to track your ovulation cycle using another method and discuss sleep solutions with your doctor in the meantime.  

Ultimately, the pattern you’re looking for is twofold: a spate of lower temperatures preceding ovulation, with a streak of slightly higher ones once ovulation has occurred. Once you identify the tipping point, you’ll be able to predict your ovulation window and which days you’re most fertile.

What should you do with this information? 

Well, you beautiful fertile goddess, when you’re trying to conceive, you should aim to get intimate with your partner 2-3 days prior to ovulation because sperm can hang around in your reproductive tract for up to 5 days. This means those little swimmers will be ready to fertilize when your egg makes its big entrance.  

How does BBT relate to the fertility awareness method of conceiving? 

If you’ve been looking into BBT, you may have learned that it’s most often associated with what’s known as FAM, or the fertility awareness method.

FAM is regarded as a modality for family planning or “natural” birth control, where an individual understands where she is in her fertility cycle using three physical indicators:

• Basal body temperature
• Cervical fluid
• Position of the cervix

You’ll have the best chance of conceiving if you’re plugged into all three of these indicators, so let’s look at what each one has to offer.

#1: Basal Body Temperature 

Now that we’ve covered BBT basics, you’re already wise to how fractional fluctuations in basal body temperature reflect your ovulatory rhythms.

Bear in mind, however, that BBT can also be affected by some other factors:

• Activity – The reason why your BBT drifts south during sleep is that your body does not generate as much heat while in a resting state. As soon as you’re up and at ‘em, your metabolic activity begins its incline and BBT will start to climb in a shift known as diurnal variation. This is why the fertility awareness method is most effective if you take your BBT while you’re in bed, as soon as you wake up. 
• Stress – You’d be hard-pressed to find a bodily system that is not impacted by chronic (or acute) stress, and that includes your reproductive system. With anxiety, the heightened disbursement of cortisol and adrenaline can lead to an incline in your baseline temperature.
• Drugs and alcohol – Cigarettes, alcohol, and even some antibiotics can all lead to irregularities in BBT.

#2: Cervical Fluid 

Another clue to where you are in your monthly cycle is learning to read the substances produced by your cervix. In an average 28-day cycle, healthy vaginal discharge will likely take the following forms on the following days:

• Days 1–8: Sticky, then nonexistent – During your period, your body produces a small amount of sticky cervical mucus. However, whatever mucus is present is difficult to differentiate from your period blood. In the days following your period, you won’t produce any cervical fluid.
• Days 9–11: Creamy and wet – A cloudy and wet lotion-like consistency indicates your body is gearing up to ovulation.
• Days 12–14: Slick and stretchy – A couple of days before ovulation and during ovulation, your cervical mucus will be slick, stretchable, and slippery—a texture that’s often compared to uncooked egg whites.  
• Days 15–28: Sticky or nonexistent – Following ovulation, your cervical fluid becomes more sticky and harder for sperm to pass through. It may remain this way until you get your period, or it may disappear altogether until your period begins. 

The texture of your cervical mucus speaks to the critical role it plays in your fertility. The slick and stretchy texture of your mucus immediately preceding and during ovulation not only works as a lubricant to lure sperm towards the cervix, but its pH value also helps sperm reach the finish line (i.e. your egg). When pH is acidic, rather than alkaline, the environment of your uterus becomes inhospitable to sperm. 

#3: Position Of The Cervix 

The final prong of the fertility awareness method is gauging the position of the cervix. Your cervix, like countless other parts of the body, undergoes miraculous changes throughout reproductive and life cycles to accommodate the changes occurring internally.

In terms of indicating fertility, you’ll find two main positions of the cervix, both of which can be understood intuitively:

• Closed – When you’re not in your fertility window, your cervix feels less pliable and sits lower in the vaginal canal. While your egg is under construction—either before or after ovulation—the walls are up (for now) to any potential suitors.
• Open – When you’re ovulating or have just ovulated, the tissue of your cervix is pliant and soft, thanks to cues from escalating estrogen. There will be a small breach (so small, you might not be able to feel it), leaving the door open for a possible pregnancy.

In most women, the cervix sits 3-4 inches high in the vaginal canal (or 5 inches if you have a high cervix). If you use this FAM method, get in the habit of checking your cervix every few days to learn what its fluctuations feel like before, during, and following ovulation. 

If you’re not used to getting up close and personal down below, feeling for cervical changes can seem mysterious, or even daunting—but it’s not much different than handling a tampon or menstrual cup. Plus, learning to read your cervix can help you build a stronger connection with yourself and your goddess-like life-creating powers. 

And remember: it’s just you! Just be sure to wash your hands and trim your fingernails beforehand.

Get to Know Yourself—and Your Baby—Better, With SneakPeek 

Whether you’re on the cusp of your pregnancy journey or just beginning to learn the language of your reproductive cycle, getting familiar with your own fertility and natural cycles will be foundational to your health, as well as the health of your new family.

Once you’ve successfully conceived, you can get to know your newest family member even sooner. The SneakPeek At-Home Early Gender Prediction Test uses DNA to reveal the sex of your baby as early as 6 weeks into your pregnancy. That’s months earlier than a traditional anatomy ultrasound can tell you. And the best part? There are no doctor’s appointments necessary—SneakPeek is the #1 OBGYN-recommended at-home gender test. All it takes is an easy-to-collect DNA sample.

So, as you begin your pregnancy journey, join the 1 million moms who chose SneakPeek, and choose SneakPeek Gender to join you in this new chapter.

Sources:

1. WebMD. What Is Normal Body Temperature? https://www.webmd.com/first-aid/normal-body-temperature
2. National Center for Biotechnology Information. Physiology, Ovulation And Basal Body Temperature. https://www.ncbi.nlm.nih.gov/books/NBK546686/
3. The Bump. Tool: Fertility Chart. https://www.thebump.com/a/tool-fertility-chart
4. ONiO. 8 Factors That Influence Your Body Temperature. https://www.onio.com/article/factors-that-influence-your-body-temperature.html
5. VeryWell Family. How to Check Your Cervix and Cervical Position. https://www.verywellfamily.com/how-to-check-your-cervix-and-cervical-position-1960299#toc-what-to-look-for
6. VeryWell Family. When And How Often To Have Sex To Get Pregnant. https://www.verywellfamily.com/when-and-how-often-to-have-sex-to-get-pregnant-1960289