By ANAHAD O’CONNOR

When Chris Garbrandt’s 6-month-old son, Will, started crawling last October, she realized the stairs in her split-level home in Nashport, Ohio, were an obvious hazard.

But as she was getting ready to go to the store to buy a stair gate, Will crawled away from his 9-year-old sister’s bedroom and headed for the staircase.

“In a flash, I heard the tumble: thunk, thunk, thunk,” she said. “I turned around, and I saw him falling down the stairs and looking like a rag doll just going all the way down. As a parent, that will forever be etched in my mind, watching him fall down those stairs and feeling so helpless. It was terrifying.”

Fortunately, Will survived with only bruises and a gash. But his experience is one that happens in tens of thousands of homes every year. A new study in the medical journal Pediatrics found that from 1999 to 2008, an estimated 932,000 children under the age of 5 — or nearly 100,000 children each year — were taken to hospitals for injuries they sustained on a staircase, usually at home. Averaged over a year, the numbers mean that every six minutes, a young child is treated in an emergency room for a stair-related injury.

“What that tells us is that we have much more that we need to do to make the home environment safer for children,” said Dr. Gary A. Smith, lead author of the study and director of the Center for Injury Research and Policy at Nationwide Children’s Hospital in Columbus, Ohio. “Children under 5 spend most of their time in the home, and even the best parent in the world can’t watch their child 100 percent of the time. It just simply isn’t possible.”

Part of the problem is that most household staircases aren’t designed with child safety in mind. Two-thirds of homes can’t accommodate a wall-mounted stair gate at the top of the stairs. About one-third can’t accommodate a pressurized gate at the bottom,

Household staircases are a hazard for Americans at both ends of the age spectrum. Falls down steps are a major source of injury and even death among older adults in the United States. But the new report is the first nationwide study to look at the extent of the problem among small children.

Dr. Smith’s interest in the subject grew in part from earlier research on mobile baby walkers, which before the mid-1990s were responsible for most childhood accidents on household stairs. Walker injuries declined sharply after new safety standards were imposed in 1997 and manufacturers began selling stationary activity centers without wheels. But the researchers wanted to see if stairs were still a major source of injuries among small children, even as baby walkers have disappeared.

The latest findings are based on data collected between 1999 and 2008 from hospital emergency rooms across the country. Of the roughly 932,000 children under 5 who were hurt on staircases, babies 12 months or younger were at highest risk, accounting for 32 percent of the injuries. In fact, stairs were the No. 1 cause of injury for 1-year-old children in the United States.

Children were several times as likely to be hospitalized with a serious injury if they were in the arms of an adult during the fall. Among stair-injured children 12 months or younger, 25 percent of them were being carried by an adult at the time of the accident.

“I knew that this was something that occurred, but I had no idea that it was that common,” Dr. Smith said.

It’s not clear how many of the children died as a result of a stair-related accident because the database lacked complete data on fatalities, Dr. Smith said. Overall, soft-tissue injuries like sprains, bruises and hematomas were the most common result of staircase falls, accounting for 35 percent of the injuries. Lacerations made up 26 percent of the injuries, followed by closed head injuries, at 20 percent.

Dr. Smith said the findings should prompt parents of small children to look closely at their staircases. Many are made with large, decorative banisters that are so thick most adults would not be able to wrap their fingers and thumbs all the way around.

“That allows only what’s called a pinch grip,” he said. “You won’t be able to hold on as firmly if you lose your balance. If that’s the case, you need to install a railing that you can wrap your hand all the way around.”

He also stressed that parents should never rely on a pressure-mounted gate at the top of a staircase, since they loosen over time and are not as secure as wall-mounted gates. But many homes are designed in such a way that they cannot accommodate mounted stair gates, or the steps are made with defects that make them uneven, making falls – among children as well as adults – far more likely. New homes, he said, should be built with stair gates installed as part of the original construction, with ways that they can be detached.

“We live in a world that is designed by adults largely for the convenience of adults,” he said. “Child safety is very often an afterthought.”