Privacy and security issues
Baby monitors operating on public transmission frequencies mean anyone with a receiver (such as a two-way radio, walkie-talkie, or another baby monitor) could listen in to conversations you have near the baby monitor. If you're using a WiFi-enabled baby monitor, set it up with a secure login password known only to you (separate to your local WiFi password). If you don't change your camera's login password from the default (which is often blank), you risk leaving your connection vulnerable to hackers.
There've been several reported cases of hackers yelling at babies via unsecured WiFi baby monitors, or accessing open webcam feeds that haven't been protected with a unique password. Make sure your WiFi monitor is upgraded to the manufacturer's latest firmware version to close potential security loopholes (the instructions should tell you how to do this), and that any associated smartphone apps are also up-to-date.