In that room, white furniture contrasted with the dark walls. A round crib, placed in the center of the nursery, put the focus on the baby. Henry hung black-and-white photos of a newborn on one wall and a canvas word mural designed by artist Dee Cunningham on another.

Cunningham urges parents to think about art that will be appropriate for children as they grow older. "You don't want to invest all this money in something you're going to change in five years," she says.

Her work includes underwater murals and an elaborate African safari scene depicting lounging lions and a charging rhino.

Blum, who writes a decorating blog, notes that birds have been popular items in nursery decor for the past few years, but she sees the trend moving toward woodland animals. Trees are always in style, she says.

Plants and animals aren't the only options, though. Smith says she likes to put letters and words on the walls. One easy way to do this, she notes, is to frame pages from children's books.

Another way to add color on a budget is to frame fabric patterns. "It's a good way to bring in a fabric you love without paying $600 to $1,000 on bedding for a crib," Smith says.

Designers say parents also can save money by moving furniture from other rooms to the nursery or buying pieces that can be moved out later. For instance, an antique armoire or bookcase can be decorated with stencils to complement a nursery or a dresser can be converted to a changing table.

Blum advises buying a neutral-colored glider so it can be moved to another room of the house when longer needed to rock the baby.

But one piece parents should not skimp on is the crib, designers note. Safety standards have changed, and even cribs only a few years old might not meet the new requirements. And in Maryland, crib bumpers are no longer allowed.

As the nursery trends change, interior designers are watching to see how Kate and Kim decorate their babies' rooms.

"Clients do enjoy borrowing elements from the nurseries of their favorite celebrities," Blum says. "I'm sure once the royal nursery is shared with the world, I will have many requests."

5 trends for nursery design

Color: Gray, black, linen accentuated by bright or neon colors

Ceilings: Crystal chandeliers, murals, 3-D images

Furniture: Repurposed dressers, armoires, gliders or rockers

Cribs: Oval or round

Wall art: Murals, framed fabric, word art, framed pages from children's books