Baby monitors are an extra set of ears--and in some cases, eyes--that allow you to keep tabs on your sleeping baby when you're not in the same room. There are two basic types: audio and video.

Audio monitors operate within a selected radio frequency band to send sound from the baby's room to a receiver. Video monitors use a small wall- or table-mounted camera that transmits images to a TV-set-like monitor.

Still another way to keep tabs on baby is with movement sensors, under-the-mattress pads that alert you when his or her movement completely stops for more than 20 seconds. While some parents may find movement sensors reassuring, bear in mind that they're not medical devices and shouldn't be used in place of prescribed heart or breathing monitors to detect conditions such as sleep apnea. Nor should you rely on them to prevent Sudden Infant Death Syndrome (SIDS), the cause of which is still unknown.

A baby monitor's challenge is to transmit recognizable sound over a distance with minimal interference from other wireless devices.


SHOPPING SECRETS

Decide how much you want to monitor. The latest generation of baby monitors claims to allow the constant surveillance of baby's every whimper, breath, and movement. For some parents, that may be comforting. For others, such nonstop monitoring is apt to be nerve-racking. So keep in mind that a monitor isn't a must-have. If you live in a small house or apartment or feel as though you'd like a break when your baby is sleeping--which is legitimate--it's OK to go monitorless.

Consider your home and lifestyle. In many situations you may appreciate a monitor with both sounds and lights so you can also "see" your baby's cries. If you'll be taking business calls during naptime, you may want to be able to turn the sound down very low and rely on the lights. A video monitor can also serve the same purpose, but it's very expensive and not very portable. Similarly, if you live in a large house, you may want a monitor with two receivers rather than just one--although that can be a convenience in a small home as well. And, in general, look for monitors with features that make them easy to move about, such as a compact parent unit that clips onto your belt. (Try it on before buying, if possible; we found the antennas tend to poke the wearer.)

Mind the frequency. None of the baby monitors Consumer Reports tested was immune from static. The closer your monitor's frequency is to that of another device, such as a cordless phone, the more likely you'll hear static or cross talk. You may reduce interference if your monitor lets you switch to a different channel within its frequency band.

Consider your phone. Choose a monitor that operates in a different frequency band than your cordless phone. Most newer cordless phones are either 2.4 gigahertz or 900 megahertz. If you have a 900 MHz cordless phone and a 900 MHz monitor, they can interfere with each other.

Check the range. Pick a model with an appropriate signal range for your home. Some home-construction materials, such as concrete and metal, can reduce the range, however.

Learn the return policy. Since you often can't test monitors before you buy them (there usually aren't display models available, and conditions in the store may be very different from those in your home), learn the return policy of the store or Web site where you're buying or registering. You'll want to be able to take back a monitor if you're unhappy with it for any reason. (Common problems include static and interference from cordless phones or answering machines, even the ambient sounds of an air conditioner or a neighbor's barking dog.)


WHAT'S AVAILABLE

The major brands, in alphabetical order, are Evenflo, The First Years, Fisher-Price, Graco, Safety 1st, SBC/Phillips, Summer Infant, and Unisar/BebeSounds.


FEATURES TO CONSIDER

Battery for the child unit. The child units tested typically can be plugged into the wall for power, but four also can use either 9-volt, AAA, or AA alkaline batteries. The parent units also have this option. The battery option is useful in the event of a power failure and also allows you to take the unit where there are no outlets, such as outdoors.

Compact parent unit. The smallest parent units are about the size of a fat wallet. You can use the integral belt clip to free your hands, but the antenna may poke you.

Extra parent unit. This unit can stay in, say, your bedroom while the other is carried about the house.

Low-battery indicator. A light or tone warns of the need to recharge or replace batteries in the parent unit.

Rechargeable batteries included. This money-saving feature is provided with some parent units. You can buy rechargeable or alkaline batteries for other parent units.

NICE BUT NOT NECESSARY

Intercom. Pushing a button and speaking into the parent unit lets you reassure your baby that you're on your way.

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Copyright © 2002-2006 Consumers Union of U.S., Inc. All of the above text is provided by Consumers Union. GuideBuy disclaims any liability for the content provided above.