Understand your health through your cycle

Track your 5 most fertile days with Ava

Your cycle can influence the way you feel throughout the month in ways you might have never considered.

As your hormone levels rise and fall, it can have subtle and dramatic impacts. Changing hormone levels can influence headaches, hunger, sleep patterns, and energy levels. It can seem like your body is changing at random, but it’s not. With Ava, you can finally start to make sense of it.

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See patterns in your health over time

With graphs, charts, and trend analysis, Ava makes it easy to compare your health and cycle details month to month.

Track your physiological stress levels

Everyone feels stressed from time to time. But the stress that you feel on the surface is different from the stress that your body is actually experiencing.

Things like exercise, poor sleep, eating habits, and more can create physiological stress, even if you don’t feel stressed. Ava reveals your physiological stress levels through a parameter called heart rate variability, empowering you to take action to reduce your stress levels.

Track sleep quantity and quality

You may think you’re getting eight hours of sleep each night, but with Ava, you’ll also see what percentage of that sleep is light versus deep/REM.

You’ll be able to see how your sleep varies depending on what phase of your menstrual cycle you’re in, or whether too little sleep might have delayed your ovulation.

Understand your fertility

Many women don’t start learning about their fertility until they start trying to get pregnant. They all say the same thing: why didn’t anyone teach them about this earlier? Knowing when you’re ovulating is just plain cool. And if you want to get pregnant someday, you’ll be way ahead of the game.

Track your cycle phases in real time

Unlike period tracking apps or women’s fitness wearables, Ava tracks physiological signals which act as markers for your hormone levels.

This allows it to sense—not simply predict—what phase of your menstrual cycle you’re in.

Track your resting pulse rate

Your resting pulse rate can tell you about your fitness, stress level, or even act as an early warning that you’re about to come down with a cold. Ava’s resting pulse rate tracking is more accurate than manually taking your pulse, because it tracks continuously throughout the night, capturing your true resting pulse rate.

What Ava can measure


The temperature of your skin at your wrist.

Skin temperature is one of the signals Ava uses to identify your fertile window. It rises by about one half of a degree after ovulation, and remains elevated until your next period begins. During pregnancy, temperature remains elevated. If you’ve ever tracked your basal body temperature orally, you’ll notice that Ava’s temperature reading is several degrees lower than your oral temperature. It’s normal for skin temperature to be lower than oral temperature, but we found that it exhibits the typical biphasic pattern during the cycle.

Average skin temperature readings (when taken at a room temperature of 64.5 – 77 degrees Fahrenheit) are between 90.5 – 98.2 degrees Fahrenheit.

For Celsius:

Average skin temperature readings (when taken at a room temperature of 18 – 25 degrees Celsius) are between 32.5 – 36.8 degrees Celsius.


How often your heart beats per minute at rest.

Scientific literature shows that resting pulse rate is lower during the follicular phase than the luteal phase. Ava’s clinical research partner, the University Hospital of Zurich, identified further variation in resting pulse rate throughout the menstrual cycle: resting pulse rate rose by about 2.1 beats per minute at the beginning of the fertile window.

During pregnancy, resting pulse rate remains elevated.

Typical resting pulse rates are between 40 and 80 bpm. If you are very physically active, your resting pulse rate may be even lower than 40 bpm. Stress, illness, and alcohol can cause temporary increases in resting pulse rate.


Rate of respiration per minute.

Scientific literature shows that breathing rate is higher in the luteal phase than in the follicular phase. Breathing rate can vary widely during the course of a day due to your activities, but typical breathing rates during sleep are much more stable, and range from 10 – 25 bpm.


The lower your HRV ratio, the less stressed you are.

HRV is the variation in the time interval from one heartbeat to the next. It can be used as an indicator of physiological stress: when there is a lot of variation in the time interval between heartbeats—high HRV—it means you are more resilient and less stressed. Ava measures the ratio between low frequency and high frequency waves in your heart rate. Because Ava measures HRV using this ratio, a lower number means you are less stressed.

Normal HRV ratio varies widely from person to person, but by looking for an increase or decrease from your baseline HRV ratio, you can learn about your body’s physiological stress level.


The process of supplying blood to the tissues of your body.

As blood flows through your capillaries, it delivers nutrients to the tissues and helps sweep away waste. Then, the blood flows back to the heart, and begins the process all over again.

If you’ve ever had an elastic band around your finger and felt the blood flow being cut off, you’re already familiar with the process of perfusion. While you can limit perfusion with an elastic band, perfusion can also change naturally for different reasons. For example, your perfusion changes in order to keep you warm or cool you down. Perfusion also changes in relation to the menstrual cycle: it is lowest at the start of the fertile window and highest in the luteal phase.


Ava tracks your movement with an accelerometer.

This parameter allows Ava to distinguish between light and deep + REM sleep.


Total sleep hours and ratio of light to deep + REM sleep.

The quality and quantity of sleep you’re getting each night are important parameters to track for your fertility. Your menstrual cycle can affect your sleep, and your sleep, in turn, can affect your menstrual cycle. Pregnancy can also influence sleep.

Ava records the amount of sleep you get each night. Additionally, Ava tracks the percentage of combined deep and REM sleep. Deep sleep is important for feeling rested the next morning, while REM sleep is important for learning and storing memories.

Typical sleep cycles for adults include 50 – 65 percent light sleep and 35 – 50 percent deep sleep + REM.

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