The pressure to redshirt is particularly high at private elementary schools in Los Angeles, where September cutoffs help to quietly encourage the practice, said Fiona Whitney, author of "The Whitney Guide," private-school guidebooks. By comparison, many other districts -- including Los Angeles Unified -- have December cutoffs.
Most top-notch schools are "very interested in having kids that will fit in," said Whitney, who also counsels parents on education matters and is a proponent of redshirting.
While children of both genders are held back, boys are more likely to start kindergarten a year late than girls, studies show.
"They tend to be impulsive or cry when things don't work; that can be really wearing," Graue said of boys. "Also there's this phobia that you don't have a teary-eyed boy. You want that kid who is confident and strong, who can lead the whole world."
As a result of interviewing many parents over the years, Graue has also come to suspect that there is another factor affecting what they want for their children: the parents' own childhood experiences.
"You might have the dad who was always the smallest and didn't get picked first in kickball," Graue said. When it's time for those people to have their own kids, you'll see "the parents who want their kid to be on varsity. It has more to do with what you want the child to accomplish. Especially with sports."