A baby monitor is a system that has two parts: a transmitter and a receiver. The transmitter equipped with a microphone is placed near the child, and the receiver equipped with a speaker is near to, or carried by the mother, so that she can hear her baby from any part of the house.
A baby monitor becomes very useful when your baby begins to sleep in their own room which normally happens at the age of 6 months. However, some people like to buy a monitor straight after their child is born, since it is very useful when you put your baby in a room for napping, or if you have to nip into the kitchen to get bottles or anything else.
So, at night or during the day, a baby monitor will release you from the task of checking on your baby every 5 minutes! Moreover, some monitors today come with a camera so that you can also see your baby not only hear him/her!
On the other hand, some mothers prefer not to have this accessory because they find it nerve-racking by making them hyper vigilant. As for you, what would you as a mother choose: using, or not, this modern kind of ears?