Image ADAPTATION Harrison Friedman with his parents, Jacqueline Brown and Gavin Friedman, grips a slippery chair. Credit... Stephanie Diani for The New York Times

Nevertheless, some people try. Ms. Brown and Mr. Friedman  who of course were thrilled to have a child, like all the later-in-life parents interviewed for this article  were also determined not to let Harrison “take control of the house,” Ms. Brown said. They went ahead with putting in flat-front lacquered maple cabinets in the kitchen, even though they soon had to watch a professional babyproofer drill 300 holes in them for safety latches. (Ms. Brown still cringes.) They put up silk Shantung draperies in Harrison’s bedroom, knowing that they might well end up stained, as they soon did  with yogurt. And they held onto the molded-wood chairs, which were not an easy transition from the highchair. “They have a very sleek bottom,” Ms. Brown explained. “He slides off it.”

OTHERS, like Debra Cherney, 49, and Hartley Bernstein, 56, were more resigned to giving up control. They were possibly even happier than most late parents at the birth of their twins, a boy and a girl named Cole and Brooke, in 2003, having lost their daughter Raine to respiratory failure in 2001. When the twins became mobile, the couple realized that they would need to create a designated play space in their prewar Park Avenue apartment. Still, the room they sacrificed  the formal dining room  was tough.

“I’m pretty sensitive aesthetically, and it does something for me when I look at a pretty room,” Ms. Cherney said. “Looking at what the room used to be was the visual equivalent of listening to Bach or Mozart. Now it’s the visual equivalent of listening to Barney.”

She felt the full impact when she and Mr. Bernstein put their 18th-century mahogany dining table and chair set in storage. “When I bought the table I was envisioning these beautiful, lovely dinners with fine china,” she said. “Once you have kids and once you give up those things, it was like, ‘Who was I kidding?’ I remember thinking this room will look nice again  in about 18 years.”

Image SOFT SURROUND Sandra McLean and Bob Stratton put down cork flooring, giving Vin (with skateboard) and Fia soft landing places. Credit... Evan Sung for The New York Times

The issue of safety, too, can pose vexing choices for parents in thrall to design. Even before Kipp Cheng and his partner of 15 years, Mark Jarecke, arrived home with their son, Beckett, last March, they could see that many of the furnishings in their Maplewood, N.J., colonial house, including a set of four Barcelona chairs and a glass-top Noguchi coffee table, were accidents waiting to happen. But they weren’t eager to act.