Opinions expressed in this blog are solely those of the author.
In high school I was taught fertility awareness NFP, and started using a chart and temping every morning for school. I have been on the pill, depo shot and had 2 IUDs and conceived with them all.
Since 2012 we have exclusively used Natural Family Planning and started with Ava in 2016. We aren’t necessarily TTC but aren’t TTA either. I am just super passionate about NFP and I am teaching my teen girls BBT (Basal Body Temperature). I discovered kegg very recently and this is my first PP (postpartum) cycle and first time back to charting (I am 19 months postpartum).
Note from the kegg team: kegg should not be used in the first 6 weeks postpartum. Please discuss with your doctor when it is safe to use kegg in the postpartum period. For women who are not breastfeeding, we recommend waiting until at least 2 cycles have been completed, (AFTER 6 weeks postpartum) before using kegg. (FAQ here)
About Ava
Ava is a wearable device that tracks multiple physiological parameters to recognize a woman’s most fertile days in real-time. Ava measures:
- Skin Temperature
- Resting Pulse Rate
- Heart Rate Variability
- Perfusion
- Breathing Rate
In order to collect your data, you need to:
- Wear ava in bed: Overnight, the Ava sensor bracelet collects continuous data while you sleep.
- Wake up and sync: In the morning, sync your bracelet to the app, and Ava’s algorithm instantly shows your results.
- See your most fertile days: Ava pinpoints your five best days to try for a baby as they’re taking place.
About kegg
Changes in the cervical fluid are the most accurate way to assess real-time fertility. kegg simplifies cervical mucus tracking with just one reading a day (about 2 minutes). Additionally, kegg doubles as an optional kegel ball for pelvic floor muscles exercises.
As a woman’s fertile window opens, the hormonal fluctuations create changes in the electrolyte levels of cervical fluid. kegg detects these daily changes and displays your predicted fertile days in the free kegg app. kegg helps predict a more accurate and precise fertile window in comparison to probability based solutions like a period tracking app, which estimates the fertile window and so rarely adjusts trends to your cycle data. The user does not need to subjectively observe their cervical mucus as kegg takes readings for you.
Note: Neither ava and kegg predict and confirm your ovulation. They both work on fertile window prediction.
My first impressions of Ava
It wasn’t very accurate and very confusing with little detail or explanation. It took me about 5 months to figure it out. [It] took us 15 months to conceive and it does not accurately pinpoint ovulation. It just gives a checkmark to indicate that their algorithm has detected a biphasic [temperature] pattern. I wear a smartwatch all day and then have to strap on a fertility watch at night. It has definitely caused some irritation from constantly wearing a watch.
My first impressions of kegg
These are my first three months with kegg. Sometimes I have to remember to take kegg with me if we plan to be out late but it is easy to use and take along. The portability is FANTASTIC considering I can charge it once a week vs ava daily. I have seen a definite pattern already with kegg and my temps and kegg lines up perfectly with my Fertility Friend app.
My ava charts vs my kegg charts
Based on info I have input into both kegg and ava, they both have similar fertility windows.



Ava Pros
- Gives an average resting pulse rate
- Gives Heart Rate variability
- Tracks sleep time
- Tracks breathing rate
- Has more options for inputting data
Ava Cons
- You must have a consistent room temperature for temps to be accurate.
- Sleep time is great, however, it doesn’t take into consideration the quality of sleep.
- Respiration are off as well as resting pulse rate
- Must be charged every night and must remember charger
- Customer service is lacking
kegg Pros
- Charge lasts at least a week
- Very portable and waterproof [note: kegg should not be submerged in water]
- Has a lovely cradle to sit in and doesn’t look awkward on the bedside table.
- Can input temps in the app
- Facebook Group Admins are very involved and respond quickly!
- You don’t have to wear it all night so it’s nearly hassle free!
kegg Cons
- Needs more option data input (I’m excited the team is releasing a new app version soon!)
- I wish to be able to layer temp and kegg readings to see how they line up
- It doesn’t take BBT. You have to input temp data manually
To whom would you recommend ava vs kegg?
I actually haven’t recommended Ava to any of my friends because the info is confusing and kind of useless. I have already recommended kegg to a couple of friends with infertility issues and have shared my charts with them.
Price comparison
Ava basic
$259
kegg
$259 (incl. FREE proov test for a value of $30)
The price for kegg was initially off putting, however, I am glad to hear that the kegg team will be adding in options to input things like cervical mucus and general notes into the app. This would also be a HUGE bonus as well!
Final thoughts?
I see many users (myself included) talking about fertility devices as ‘ovulation detectors’ but the majority – rightfully so – detect your full fertile window, giving you so much heads up on when you will be the most fertile. One last note. My ava just gave out last night so I have chosen not to buy another. I will keep taking my readings with kegg though. Overall I am not only impressed but my husband is as well. Can I wish for something? I would love – one day – to see a new feature in the kegg app to overlay temps and kegg data. This would draw in A LOT of other users.
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