A baby monitor transmits sound, and sometimes video images, from one room to another, so you can keep tabs on your little one from any part of the house. Monitors have two parts – a transmitter and a receiver – and are particularly useful with infants who sleep in a room apart from their parents and wake up at night for feeding, changing, or comforting. Monitors are great for naps, too – you can be occupied in another part of your home and hear when your child wakes up and wants you.
For best results, place audio monitors within 10 feet of your baby's crib so they'll pick up every sigh, gurgle, and wail. You can carry the receiver around the house or leave it plugged in by your bed.
Video monitors need to be close enough to get a good image of your baby. Trial and error should help you determine the best distance.
Indispensable as they are, monitors aren't without flaws: Concrete walls can block the signals, cordless phones and wireless systems can interfere with reception. Also, your receiver might be able to pick up audio signals from your neighbors (and theirs from you). Video monitors that don't encrypt their signals can also give other people a peek into your baby's room, so it's wise to choose a model with strong security features (see "What to look for when buying" below).
"At least once a week, we pick up another family's child on our baby monitor," says a mother of one in San Francisco. "We've learned never to discuss anything private when the unit is on."
What to look for when buying
Analog or digital: Analog monitors are less expensive, but the sound quality is usually not as good as that of digital models. Analog signals are transmitted as radio waves, which means anyone in range can listen to the signal. Digital models convert sounds into data, which makes it almost impossible for other people to eavesdrop.
Audio or video: Do you want to watch while your baby sleeps, or just make sure you can hear when he wakes up? Audio-only monitors are less expensive and usually take up less space. Video monitors offer a wide variety of options, including different screen sizes, cameras that pan and zoom, and even night-vision images for nighttime viewing.
Security: Look for monitors that use DECT technology (that's digitally enhanced cordless telecommunications) to encrypt the audio signals between the transmitter and the receiver. For video monitors, digital models offer better security. Some models have a "digital lock" to encrypt the images.
Frequency: The most basic models use 49 megahertz. The next step up is 900 megahertz, which delivers longer range but also might be subject to interference from older cordless phones that use the same frequency. To address this, many baby monitors have shifted to 2.4 gigahertz. Newer cordless phones have adopted the same frequency, however, and wi-fi systems also use 2.4 GHz, so interference can still pose a problem. The 1.9 gigahertz band offers the best security because it's the only one that supports DECT technology.
Size: The smaller the receiver, the more easily you can carry it around the house.
Low-battery indicator: If the batteries run out of juice, you might not hear your little one calling out for you or singing all the words to "I'm a Little Teapot." Get a monitor that lets you know when to change the batteries with an alarm or flashing lights.
Sound-activated light: If you're vacuuming, calming another child, or watching TV, you might miss your baby's whimpers. But a unit that lights up when it detects noise allows you to glance at the monitor and know instantly that something's going on.
Multiple receivers: Some models have two receivers. This may be handy if you want to leave one in your room and carry the other around the house or out back. With certain brands, you can buy additional receivers.
Multiple transmitters: One mother was thrilled to find a multi-room system with three transmitters that let her monitor up to three kids' rooms and two walkie-talkie receivers. They can scan all three rooms or only one room, and each receiver has a light-up display. However, all these gadgets in one house might interfere with each other's signals.
Other features: With so many models on the shelves, there are plenty of cool options. Some monitors can keep track of the temperature in your baby's room, send out an alert if the baby hasn't moved recently, or connect to the Internet so you can check on your child online or with a mobile phone.
Important safety notes
If the baby monitor has a cord, make sure it's well out of your baby's reach – not within 3 feet of the crib, says the Consumer Product Safety Commission (CPSC). Babies have strangled on these cords and died.
Also, to prevent accidental shocks, never place a baby monitor in or around water.
What it's going to cost you
Audio monitors start at about $20 for basic models. More advanced designs, with better security, multiple receivers, and longer range can cost as much as $100. Video monitors start at about $75 and can go as high as $300, depending on range and image quality.
