What is the fertile window

What Is the Fertile Window? Cycle Tracking Fertility for Faster Pregnancy

cycle tracking fertile window fertility pregnancy Oct 09, 2020

If we relied on high-school sex-ed for our fertility information, we might think that if women were to even look at a man – then BOOM – she’s pregnant. 

But for many of us, our experience doesn’t match the biology lesson. At all. For us, the journey to parenthood can be much more challenging. 

There are actually a few days each month where it is even possible to conceive. Cycle tracking can help you to accurately identify that time period so that you can conceive, faster. 

So, what is it?


Cycle tracking is the process of gathering a bit more data on what your body is telling you and offers a window into your own fertility. 

And while these messages may not seem as loud or clear as your deep desire to become a mother (yet), the messages offer valuable information, if you learn the language. 

Let me help you to track and translate!


Whats and Whys of Cycle Tracking For Fertility and Contraception

Some women have a cycle that is 28 days long. They ovulate halfway through and it is consistent and predictable. 

However, many women don’t. There are a lot of factors at play, which we’ll talk about at the end, but not having a predictable cycle makes the optimal timing of intimacy much more challenging to nail down. 

There are only a few days each month in which your egg is open for the business of being fertilized if your body even releases an egg. And if you didn’t ovulate, no amount of intimacy will result in pregnancy. 

So, how do you know?

Cycle tracking empowers you to tune into your body’s natural rhythms so that you can learn if your body is ovulating (aka releasing a healthy egg that is ready for fertilization), or if your hormone levels are not optimal.

The good news: if you find that your hormone levels are not currently optimal, there are lifestyle modifications that will help improve them and your fertility – that’s exactly what I empower my clients to do!


Three Elements of Cycle Tracking 

There are three main signals we are tuning into to track and monitor your body’s fertility:

  • Basal Body Temperature (BBT for short)
  • Cervical fluid (sometimes called cervical mucus)
  • Cervical position


Basal Body Temperature

Basal Body Temperature is the daily tracking of your temperature, first thing in the morning, before you move, talk or do anything else. Best practice is to measure your temperature at the same time each day. 

These days there are Bluetooth thermometers that track and log your temperatures automatically to your phone log. Look for one that measures your temperature to the 100th of a degree.

You can take your temperature orally using one of these. There are also wearable devices, including an armband that tracks your temperature as you’re sleeping, and a vaginal thermometer that you insert like a tampon each night before bed. 

What you’re looking for is a slight spike in temperature (at least ½ of a degree F) that occurs the day after you ovulate. This temperature rise should be sustained throughout the rest of your cycle to confirm ovulation. We’re the most fertile right before and during ovulation, so tracking patterns is what helps us to better predict ovulation in subsequent cycles. The spike that you can measure in the moment, along with changes in your cervical fluid, is the end of the fertile window.


Cervical Fluid

As your hormones ebb and flow throughout the month, your cervix is releasing fluid. Throughout your cycle, the amount, color and consistency of your cervical fluid changes. These changes are actually a clue to your fertile window (1, 2). 

  • During your period: you’re still making cervical fluid, but you’re probably not going to notice because of your menstrual blood.
  • After your period: you may have the least fluid produced and you may feel more dryness during intercourse.
  • Before ovulation: your cervical fluid might be cloudy, white, or similar to the consistency of lotion.
  • Right before ovulation: your cervical fluid might remind you of egg whites - clear, stretchy and watery.
  • During ovulation: your cervical fluid is stretchy and sticky, it may be white or clear, and you should be able to stretch this fluid between your finger and thumb for several inches before breaking. This may be when you make the most cervical fluid in your cycle. 

You can check your cervical fluid by wiping with toilet paper before you go to the bathroom, inserting a finger into your vagina and observing the fluid or by looking at your underwear. 


Cervical Position

Checking the position of your cervix is one more message in your body’s fertility language that you can track. Cervical position is more of a secondary sign of fertility that works best when you combine your observations with your BBT and cervical fluid patterns. 

To track, wash your hands and find a position that is comfortable for you. Some women sit on the toilet, prop a foot onto the edge of the tub, or squat. Insert your clean finger and locate your cervix; it is firm and round, in contrast to the softer walls of the vagina. 

Just like learning a new language, this will take some practice to understand what your cervix is telling you. If you’ve never checked your cervical position before, it’s best to check every day for one full cycle to sense and feel the changes. Not much changes until you approach ovulation, so stay the course! During ovulation, your cervix is higher in your vagina. 

Once you feel the changes, you’ll appreciate having this added fertile sign to help you confirm ovulation and identify your fertile window.

Here is what to check and log:

  • Texture. While the cervix is always a bit firm, it is relatively softer during ovulation. Estrogen is the hormone at work here.
  • Opening. Your cervix will be slightly open during ovulation and during your period. 
  • Position. Is your cervix high, medium or low? The closer you are to ovulation, the higher your cervix will be. Again this is all relative, so as you learn your own body, the messages will be more clear. 

Note: during or after sex is not an accurate time to monitor cervical position because your cervix moves with arousal.


Cycle Tracking is a Mirror to Your Hormone Health

More than simply graphing some personal data each day, tracking your menstrual cycle will provide a true reflection of your hormone health.


Did you ovulate?

Tracking your BBT, cervical fluid and cervical position can let you know if you’ve ovulated or not. At a minimum, this helps you to be able to better identify your fertile window to optimize your timing of intimacy. 

And if you did not ovulate, that may feel disappointing, but it is helpful information too. If this is the case for you, this gives you a new target to work on.

Is your progesterone too low?

As you’re tracking your BBT, if you see no sustained rise in BBT during your luteal phase, your cervical fluid doesn't dry up, or your luteal phase is short, these can all be signs that your body is not producing enough progesterone. 

Progesterone is the hormone that thickens the lining of your uterus each month. If your uterus is not thickening, it won’t be able to have an egg implant into it following fertilization. So, even if you have a fertilized egg, you won’t conceive.

Is your luteal phase long enough?

The luteal phase for many women ranges from 12-14 days, but 11-17 days is considered normal. 

During the luteal phase, your uterine lining should be thickening. If the phase is too short in your cycle, your uterus doesn't have enough time to meet the deadline to be ready for implantation. Without a thick enough uterine lining, pregnancy is unlikely (3). 

Note: smoking can shorten your luteal phase (4).

Is your thyroid underperforming?

If your thyroid is not performing optimally, this can impact your ability to conceive. Here are a few signs that might indicate that your thyroid is sluggish. 

  • BBT consistently below 97.5 ºF / 34.6 ºC  in the follicular phase
  • No ovulation or delayed ovulation
  • A short luteal phase (less than 10 days)
  • A very short or very light cycle (cycle less than 21 days)
  • Abnormal cervical fluid patterns (either very little or continued production)

From a functional nutrition standpoint, there is a lot that goes into thyroid health. Even if you’ve gotten your TSH (thyroid stimulating hormone) measured before and it’s “normal”, please know that there are several other lab tests that dive deeper into thyroid health. 


What Lifestyle Factors Influence My Cycle and Hormone Health?

There are many factors that influence your cycle health. Tracking your menstrual cycle to identify your fertility window is painless, accurate and gives you a ton of information about if your body is ovulating. 

And if you find that your cycle is not optimal, or you’re not ovulating, know that there are lifestyle factors that you can modify to improve things. 

Getting a good night’s sleep, having consistent exercise that feels good, minimizing or eliminating alcohol and reducing stress are all important pieces of your overall health, wellness, hormone health and fertility. 

As a registered dietitian, I help you to optimize your dietary habits to better support your thyroid health and fertility. We'll use your cycle chart as a tool to individualize your care, and I can also make recommendations about safe supplements you may want to consider.

If you’re a woman who feels like you’ve already done everything and are frustrated that you’re not yet pregnant, please know that I have been in your shoes. It is so, so tough. But also know that cycle tracking is valuable information – and with the right practitioner, you can use that information to identify and remove underlying barriers that are getting in the way of your fertility. 

If you're ready to start looking at your cycles more deeply, you can set up a FREE 30-minute strategy session HERE. You'll discover the exact next steps you need to take to start nourishing your thyroid and all your hormones today!

In joy and health,


This information is not intended to be personal medical advice. Never start a supplement, change a medication, or make any other modifications to your health regimen without first consulting with your physician or appropriate health practitioner.

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