You might see monitors on the market with claims that they can track a baby's breathing or movements, but unless the unit is registered with the FDA, it's not a medical device. Consumer Reports hasn't tested this type of monitor. Talk with your pediatrician if you think your child has a condition that warrants medical monitoring. He or she can give you advice on the best devices.
To save on battery life, some audio/video models only turn on when the baby makes an unusual motion or sound. Some models come with a motion-detector pad that fits under the crib sheet. This type of motion sensor is intended to prevent SIDS. Sensitive enough to detect changes in breathing, an alarm sounds if there is no movement after 20 minutes. However, if the baby simply rolls off the pad, the alarm may sound.
Ease of setup and installation factored heavily into our ratings, including whether an account needed to be created and if there were any extra subscription fees necessary. Each unit had cords protruding out of its back, so design wasn't much of a factor in my choice, though parents should take care to keep dangling cords and wires away from their children's reach when setting up a monitor.
Wireless encryption: This ensures that no one else can tap into your monitor’s “feed” and see what’s going on in your house. WiFi-enabled monitors are great for portability and range, but may be more susceptible to hacking. If you go this route, be sure to secure your home wireless network and keep the monitor’s firmware updated. Otherwise look for digital monitors with a 2.4 GHz FHSS wireless transmission.