Back in the 'olden days', to check if your baby was asleep or instead screaming over a misplaced dummy, you had to be in the room with the little darling. This could be seriously disruptive to a night of TV watching (or more accurately, a night of laundry). Even more disastrous, the accidental wake-up – going in to check if baby is sleeping, only to wake them with a creaking floorboard or the click of a door.

But in this brave new world, with the aid of a baby monitor, you can hear your bub and even transmit soothing sounds to them from virtually anywhere. Baby monitors give you the chance to get on with other activities, knowing you'll be the first to hear when your baby calls.

While they're not a must-buy, baby monitors really come into their own if you have a large house, especially two-storey, or your baby's room is some way from the kitchen or living areas of your home. Basic audio-only baby monitors are still effective, but you may be considering other features such as video, Wi-Fi connectivity or movement sensors.

What to look for

Sound range, interference and sensitivity

The baby monitor should maintain a good quality sound, even when you're at the other end of the house. The monitor should also be able to pick up and reproduce soft sounds. Baby monitors using common radio frequencies may pick up signals and interference from other nearby devices (including your neighbours') such as cordless phones, microwaves, or other baby monitors. Some monitors let you choose from several frequencies to minimise this. Monitors that use DECT (digital enhanced cordless communication) are more private and offer less interference as the frequency isn't as common as other devices in the home. They may also work across wider distances. Wi-Fi monitors can also be more private if you configure your privacy settings properly.

Movement monitor

To sound an alarm when there is no movement after a certain length of time. Something to consider in light of SIDS (sudden infant death syndrome).

Infrared camera

Keep in mind that while baby monitor cameras generally transmit a clear picture with good colour during daylight, in dim and dark lighting the image shows up as black and white, and can have poor contrast.

Camera viewing angle

Where will the camera need to be positioned? Cameras lacking wide viewing angles mean you may not get your baby entirely in shot. Some cameras can be controlled remotely with a pan and zoom functions so you can keep better track of what's going on.

Lullaby mode

Some monitors let you play a tune into the room to gently send baby off to sleep.

Sound indicator lights

The sound indicators will light up to alert you when bub cries. They allow you to 'see' the noise your baby makes rather than hear it. This is particularly useful if you're talking on the phone, have visitors or you're in a noisy room, or if you or other carers have hearing difficulties.

Battery operation

If the monitor is only powered by the mains, you can't use it in areas that are unplugged – for example, if you're hanging out the laundry or gardening.

Baby room temperature monitor

Some models allow you to set an upper and lower temperature limit and the monitor will sound an alarm when the room temperature goes above or below them.

Two-way communication

For when you can't immediately respond to your baby's call. Allows you to soothe bub from another room, and even communicate with someone else who's in the room with your little one.

Other features on some baby monitors

  • Low battery indicator.
  • Carer unit belt clip.
  • A night light.
  • Volume control.
  • SD card slot to record sound and video.

Wi-Fi baby monitors

These can be viewed anywhere with an internet connection, as long as the baby monitor is in Wi-Fi range with a good signal and the carer unit is in Wi-Fi or 3G range. Some have smartphone compatibility, so you can download an app and monitor your child remotely, and so can family and friends all over the world. If you're going to view your monitor over the internet, make sure the connection is secure and that the firmware is up-to-date (see Baby monitor privacy and security issues).

How far you can use the Wi-Fi signal on the carer unit depends on the strength of your Wi-Fi. Once Wi-Fi is lost, the 3G signal will kick in for the carer unit. However, be wary of areas in the house where both Wi-Fi and 3G signals may be poor – you wouldn't want the signal to drop out without you noticing.

Make your own baby monitor

You can turn two smartphones (or tablets) into a baby monitoring system by downloading a suitable app to each device. There are plenty of apps around to choose from, and because they only cost a few dollars they may be worth a try if you have a spare smartphone lying around. The 'child' unit uses the device's built-in microphone and camera to check baby's sound and movements, while the 'parent' unit lets you keep an eye and ear on them from wherever you are. One downside is that picture quality in dark lighting conditions can be very poor unless you turn on the phone's light which could disturb baby's sleep. And, like all internet-enabled devices, it won't work if your connection goes down.

Cordless phones as baby monitors

Some cordless phones can be used as baby monitors. This allows you to put the handset in bub's room and set it to monitor sounds, which will be transmitted to the base unit.

Baby monitor privacy and security issues

Audio baby monitors operating on public transmission frequencies mean that anyone with a receiver (such as a two-way radio, walkie-talkie, another baby monitor etc) could listen in to conversations you have near the baby monitor. If you're using a Wi-Fi enabled baby monitor, set it up with a secure login password known only to you (separate to your local Wi-Fi 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 remotely yelling at babies via unsecured Wi-Fi baby monitors, or accessing open webcam feeds that haven't been protected with a unique password. Make sure your Wi-Fi 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.

SIDS and baby monitors

There's no evidence that using a baby monitor will prevent SIDS.

Cost

Baby monitors in our latest test ranged in price from $70 to $400.