An Honest Review of Fitbit for Menstrual Cycle Tracking

You may know that the Fitbit app has some built in menstrual cycle tracking features, but many people do not know that it has other features that may be useful for menstrual cycle tracking. In this article, I will review the pros and cons of the Fitbit app as it relates to cycle tracking for people who ovulate. For context, I use a Fitbit Charge III.

The most basic feature that Fitbit offers for cycle tracking is recording bleeding dates of menstruation and then displaying a predicted fertile window based on average cycle length.

The pink bar represents the length of menstruation. The blue bar represents a predicted fertile window. The flower symbol represents predicted ovulation.

The user needs to remember to input menstuation each cycle. Once it is inputted, Fitbit will generate the blue fertile window. This fertile window should NOT be used for avoiding pregnancy, as it is only based on cycle length and not real-time fertility signs like cervical mucus or basal body temperature.

Once menstruation is entered, it will also begin a countdown until your next predicted menstrual cycle.

Countdown until menstruation in the app.

Unfortunately, I do not find this basic feature very useful for anyone who has any cycle variation. Even though my cycle length has increased over the last year, Fitbit has not automatically updated my cycle lengths. The app does not appear to be very adaptive without user input.

In addition to tracking bleeding the app offers options for:

  • Mood
  • Plan B (morning after)
  • Ovulation tests (better called luteinizing hormone tests)
  • Cervical mucus (Taking Charge of Your Fertility categories)
  • Cyclical symptoms like acne

It is rather disappointing that the app does not include options to mark pregnancy when it occurs, especially since we know that this changes daily calories burned and heart rate, to name just two effected areas of the app.

A really cool feature that I do like is the ability to show cycle trends like flow intensity and cramps. The same screen that displays this will also let you scroll through all past cycle lengths.

In the settings of this screen, you can also decide to toggle off predictions. For people avoiding pregnancy, I do recommend either ignoring or toggling off predictions in the Fitbit app. The app allows you to choose your current birth control method as well.

Outside of the designed menstrual cycle tracking features, I want to highlight resting heart rate as a potential exciting thing to track for those who are not taking hormonal contraception. Why do you need to not be taking hormonal contraception to utilize the heart rate feature for menstrual cycle tracking? Hormonal contraception suppresses ovulation, and ovulation changes our heart rate charts!

To learn more about resting heart rate and the menstrual cycle, read my previous post here.

You can see my heart rate falling during menstruation around April 10th, and then rise during my fertile window and luteal phase.
Menstruation began when my heart rate dipped below 70 on this chart. Ovulation likely occured around the third raised heart rate in this close-up.

Heart rate in people who are ovulating is at its lowest point during menstruation, rises during the fertile window, and continues to be elevated in the luteal phase.

When heart rate begins to drop again, this is an excellent way to predict menstruation will soon occur. For example, I have been tracking my heart rate in Fitbit for 2 years, and I always bleed when my heart rate dips back down to 70 beats per minute after my luteal phase!

I do think this feature is worth tracking for anyone interested in a more precise period prediction than cycle length. If you have Fitbit premium, you can also find a setting for sleeping heart rate under restoration. This may be more steady than resting heart rate for some individuals.

Lastly, I want to address Fitbit temperature for menstrual cycle tracking. Unfortunately, wrist temperatures are not a compatible parameter for fertility awareness when it comes to avoiding or achieving pregnancy. It can be incredibly erratic. When we track temperature, we want the temperature as closest to the core as possible.

Fitbit does not give precise temperatures, instead it gives deviations from a range. I likely ovulated near 18, 19, or 20 on the photo above. While Fitbit did detect a slight shift, it is not particularly clear, and it dropped back down.

As depicted above, my luteal phase the previous month was extremely undefined, and I could not determine a confirmed temperature shift with it.

For now, I do not recommend Fitbit for precise temperature tracking. Instead, I recommend a basal body thermometer.

Conclusion

Fitbit offers some really unique options for cycle tracking, but it should not replace your birth control or fertility awareness method. The heart rate feature may be useful for identifying cycle phases, but the temperature readings are not suitable for tracking cycle phases.

6 Cycle Comparison: Marquette Versus Billings Versus DOT Fertile Windows

Have you ever been curious what your fertile window would look like in multiple methods?

In this blog, I show 6 cycles with various fertility signs and method interpretation including: the sympto-thermal method (Sensiplan rules), Marquette method, the Billings Ovulation Method, and DOT (a calendar method that was recently purchased by Clue app and is a new FDA approved birth control). I chose to include representation for only studied methods of fertility awareness: sympto-thermal, sympto-hormonal, mucus-only, and calendar method.

All charts are from the Read Your Body app, a flexible app for all methods that I highly recommend!

Some things to know before reading:

  • Marquette allows sex any time of day within their rules. My calculation rule lasts until the end of day 7.
  • Sympto-thermal method allows sex any time of day during first 5 days of menstruation, but the first safe day in the luteal phase must be used in the evening. My calculation rule is day 5.
  • Billings Ovulation Method allows sex in the evenings only and on rotated days in the pre-ovulatory time of the cycle. Days of bleeding where mucus cannot be observed are not allowed. However, since you can have sex any time of day post-ovulation with Billings, sometimes cycle day 1 is available if you have sex before bleeding occurs.
  • DOT allows sex any time of day within their rules. It automatically opens my window on day 7.

Cycle 53

Consecutive Fertile Window for Expected Abstinence:

Billings: 8 days

Sympto-thermal: 12 days

Marquette: 12 days

DOT: 12 days

General remarks: This is an extremely standard cycle in length and mucus patch (the average person will have a 5 to 6 day mucus patch when charting). I believe this is a great example of what methods would look like for someone of the average cycle length.

Cycle 54

Consecutive Fertile Window for Expected Abstinence:

Billings: 9 days

Sympto-thermal: 21 days

Marquette: 15 days

DOT: 12 days

General comments: My average coverline is 96.8 to 97.0, so regardless of earlier high temperatures and some illness I felt confident marking this coverline and temperature shift. Due to continous long, clear-ish mucus, my sympto-thermal peak was extremely delayed. Billings is a sensation focused method so I was able to mark my peak at an earlier time and have less expected abstinence.

DOT gave me a very risky day on this one. It is possible I could have been ovulating near the safe day. However, that would have only left 9 to 10 days for implantation and I had spotting, so whether this truly could have ended in pregnancy is up in the air. Even with well-timed sex, pregnancy will not always occur.

Cycle 55

Consecutive Fertile Window for Expected Abstinence:

Billings: 6 days

Sympto-thermal: 12 days

Marquette: 12 days

DOT: 12 days

General comments: This small fertile window in Billings might look scary to some, but it is not possible to get pregnant when the cervical mucus plug is truly closed. I have about one cycle like this every 13 cycles. I was also using the Kegg device during this cycle which is placed internally and reads electrolyte levels to determine the fertile window. It gave me the same 3 day dip for a fertile window, so I feel even more confident that those days were truly dry. I am missing temperatures on this one because my thermometer glitched and would not give me readings on these days. Sex day 1 was allowed because menstruation didn’t start until 5pm.

Cycle 56

Consecutive Fertile Window for Expected Abstinence:

Billings: 8 days

Marquette: 11 days

DOT: 12 days

General Comment: This was an extremely heavy period so I had no period days available in Billings. Even though the other methods gave me available days, I couldn’t have used them due to the pain, so ultimately the other methods didn’t really help out on more safe days.

Cycle 57

Consecutive Fertile Window for Expected Abstinence:

Billings: 10 days

Marquette: 14 days

DOT: 12 days

Cycle 58

Consecutive Fertile Window for Expected Abstinence:

Billings: 9 days

Marquette: 11 days

DOT: 12 days

General Comments: Marquette monitor missed my peak on this cycle. It misses peak on up to 10% of cycles. I relied on meeting LH rules instead of the monitor. Sex day 1 was allowed because menstruation didnt start until 1pm.

Reflecting on What’s Best for Me

I’m currently on cycle 59 charting, and I have tried a ton of methods. Right now, my ideal method is Billings and LH tests as a bonus marker.

While it may appear that Billings gives less safe days in some instances, what is most important to me is having the smallest consecutive fertile window. Having less expected abstinence actually makes me more likely to follow the rules. I was completely unsatisfied with only being allowed period sex in the sympto-thermal method because I have period pain issues. That means that I basically had no safe days at all in reality before ovulation with sympto-thermal.

I originally felt very enthusiastic about Marquette method. However, after 6 cycles of using the Clearblue Fertility Monitor, I realized that it always caught my LH surge after the cheap LH tests. In addition, it missing my peak even once is frustrating for the cost of the product. For that reason, I have decided to stop using the monitor when I run out of tests. I can use a 15 cent LH test and get the period prediction aspect (LH is my most steady indicator).

The DOT app tends to give me a risky cycle whenever I ovulate late and have a shorter luteal phase. I do not rely on this for pregnancy prevention. Overall though, DOT has not given me many risky ways. I use it for long-term period prediction, and it is the most accurate period predictor I’ve ever used for planning months in advance.

What to Consider Before Switching Methods

1. Why are you unsatisfied with your current method? Is it the amount of safe days, or is it the routine that you don’t like?

2. Do you have medical needs that could be addressed by another method?

Sometimes the grass isn’t greener on the other side, but if you are like me and can’t have period sex or don’t want to have period sex, methods like Billings without calculation rules will almost always include more safe days if you are dedicated enough to learn the method and chart it accurately.

Folks in irregular cycles like in postpartum time or with PCOS may benefit from more flexible methods without calculation rules

*DISCLAIMER: DO NOT TRY TO LEARN FROM MY CHARTS. MY CHARTS ARE NOT YOUR CHARTS.

An Honest Review of Pearl Fertility Kit

I tried the Pearl Fertility Kit. During my first kit, I got a little confused when the kit did not seem to line up with my fertility signs. However, I contacted Pearl Fertility and they were super helpful. They sent me another kit for free, and it worked perfectly when I tried it this last cycle.

Pearl is a product marketing to women who are trying to conceive (TTC). The product explicitly states that it should not be used to avoid pregnancy. The kit contained 15 follicle stimulating hormone (FSH) strips, 15 luteinizing hormone (LH) strips, and 4 progesterone (PdG) strips. It also included a few pink dye pregnancy tests. As I am not currently trying to conceive, I did not use these.

The app claims to open a woman’s fertile window by scanning the FSH and LH strips and giving you a fertility window from these results.

If anyone wants to try this product, I highly suggest tracking your cervical mucus, as good quality cervical mucus (eggwhite, clear, stretchy, wet) is what allows sperm to survive to meet an egg. Progesterone tests need not be used until at least 4 days past your peak day (the last day of good quality cervical mucus). Even then, some women do not see positive progesterone tests until as late as 7-10 days past ovulation. For more information, visit Proov’s website linked at the end of this article. By charting your real fertility signs, you could use these tests more wisely.

Overall, I thought the Pearl Fertility Kit was super cool. FSH strips are a brand new thing, and I have high hopes for them being integrated into a real fertility awareness based method in the future. If you have the money to invest in Pearl, this can be a fun kit to experiment with. Basically you get to see three main hormones of the menstrual cycle play out. Pearl graphs them for you.

If you cannot afford Pearl, do remember that it is free to chart cervical mucus and that this is always the best indicator for when to have sex when trying to achieve pregnancy. Without cervical mucus, sperm will never make it to the egg on its own.

Here is what my Pearl chart for this month looks like:

The highest pink dot is my positive LH strip.

Here is my Pearl information compared to my symptothermal method chart. In this chart, FSH equals Ferning since Kindara does not have an FSH category.

The Pearl fertile window is indicated by the green lights. It did start my fertile window on a day pregnancy was unlikely since there was no mucus. The blue hearts represent the fertile mucus where sperm can survive. These two fertile windows lined up pretty well.

Overall, I would rate myself satisfied with this kit.

One tip:

From the calendar screen, you can override what tests Pearl is asking for. I only suggest doing this if you are charting your other fertility signs (cervical mucus and basal body temperature) and know that something is not lining up right.

In addition to the strips, Pearl has spaces to track intercourse, your period, and pregnancy status.

Curious to know more about the fertility signs?

If you want to learn how to chart your real fertility signs to achieve or avoid pregnancy, read my guide to getting started.

Look for my next blog on using Proov progesterone tests.