Listening to a baby coo, or even watching her fret in the family nursery, has become practically a pastime among young parents, a trend that experts say has grown over the past 15 years.
There are the babies' toys, a gigantic industry with more than $5 billion in annual sales. Then there are the baby toys for adults, including the monitors, the lullaby machines and other gadgets and gizmos that comfort and cater to babies and those who love them.
On the serious side, innovations will bring wearable computers for infants who, for example, need to have their vital life signs monitored constantly.
But the hot items right now are the gadgets that dominate the baby shower: the constant ears and unblinking eyes that keep parents in touch with a sleeping baby, even as parents relax in the family room, do chores or entertain on the patio.
"We watch to see if the baby is resting and comfortable," said Beth Van Winkle, proud mom of Fritz, who is 7 months old. "And one of the joys is that you can check without awakening him."
The Van Winkles and others do their watching by way of the latest device, a home network that lets you hear and see the baby on multiple monitors. Mom and Dad can watch the baby independently, then confer to compare impressions chatting over the network.
This is one of the latest wrinkles in the nursery monitor, a gadget that has been increasing in use for more than 15 years, said Jerry Perez, executive vice president for marketing and design at Fisher-Price, the children's products company.
"Though we don't break out the figures for infant monitors as a sector of our children's products, I can say that such products for infants is among the fastest-growing businesses for us," Perez said.
It's a young parents' game, basically, with first-time parents most likely to want them, the experts say.
"Most of us get our monitors and other equipment as baby shower gifts," said Jamie Hubbard, mother of 3-month-old Molly.
Chuck and Jamie Hubbard got plenty of electronic gadgetry in a baby shower, but later they added a dual TV monitor system.
"After a few weeks of just listening to the baby, we realized seeing her was better, more comforting," the new mother said, "because you can actually see the baby's behavior and see body language."
Some moms check in mostly by listening.
"The Fisher-Price Sounds N Lights monitor is about our most popular," said Stephanie Holloway, the baby tech specialist at Babies "R" Us.
Selling for less than $50, Sounds N Lights allows up to two monitors for listening in. It also displays the baby sounds in lights.
At the other end of the spectrum, high rollers can pay $469 at the Sharper Image for a 2.4-gigahertz monitor in color, sight and sound. The camera and monitors are in cool-looking chrome and black.
The significance of having the 2.4-GHz monitor rather than the lower spectrum 900-megahertz devices is that the higher-spectrum machine is less likely to encounter interference or "cross-talk" from other things such as portable telephones - either in the house or in the neighborhood.
Also, compared to the 100-foot range of less-expensive devices, the Sharper Image machine has a range off 100 yards.
"If you live in the country, or live rather simply without a bunch of competing equipment in the house, the cheaper 900-MHz things might do just fine," said Holloway of Babies "R" Us.
A less expensive 2.4-GHz alternative is the Safety 1st Child View TV system, for $149, which uses infrared lighting to convey pictures, thus helping Mom and Dad pry into baby's business without awakening him.
Though it is not made specifically for the infant and baby market, computer technology offers another option. A webcam, such as the x10 camera, can also act as a monitor - relaying pictures to personal computers, television sets and VCRs, all wirelessly (www.x10.com/products/x10vk45a.htm).
Suppose Baby seems fretful in the sound and pictures on the monitors - then what? In some systems Mom and Dad can confer on a home network and come up with an action plan.
If they are too occupied to pick up the baby for a little tenderness and consolation, they can do it remotely through the magic of technology. Some monitors are two-way, enabling Mom and Dad to sing a lullaby or press a button and play a prerecorded lullaby.
An example of this technology is the Fisher-Price Soothing Dreams machine, for $49.95.
Other systems provide a soothing vibration through the feet that many babies find especially calming.
For the youngest infants, devices such as Mommy Bear ($19.99) can provide either prerecorded sounds of a parent's voice or the sounds of the maternal heartbeat - a kind of placid return to the womb.
Finally, for kids with medical problems, there are special systems, including some that may become commercially available.
Engineers at Georgia Tech have been working with doctors at Emory University in Atlanta to adapt battlefield technology to the monitoring of baby health.
Efforts to translate the so-called Smart Shirt for troops into a baby jacket monitor have been inconclusive.
"The technology is terrific," said Dr. Gary Freed, an Emory pediatrician. "But there are still user-friendliness issues to be worked out."