More parents are delaying their child's entry into kindergarten so that the child will be older than his or her peers.(Getty Images)

More parents are putting off a child's kindergarten entry so he or she will be a little older than the classmates. It's a phenomenon known as redshirting.

"The reasons parents choose to redshirt their child vary, depending on the child's emotional, social and academic readiness to join school," Dana Vela, president of Sunrise Preschools, in Arizona, said in an interview with ABCNews.com.

"It has always been in practice, but it has gotten more attention recently and people are talking more about it," said Vela, a mother of three and a preschool teacher for 25 years.

Parents might think their child is not emotionally ready to leave home, or not socially or academically adept. Some parents are even delaying schooling to give their children a competitive advantage in sports, or to delay admission age to college.

A joint study by the University of Virginia and Stanford University released in 2013 established a relationship between red shirting and socio-economic status and ethnicity. "We find that between 4 and 5.5 percent of children delay kindergarten, a lower number than typically reported… We find substantial variation in practices across schools, with schools serving larger proportions of white and high-income children having far higher rates of delayed entry," noted the report, "The Extent, Patterns, and Implications of Kindergarten 'Redshirting,'" issued in April 2013.

According to a report issued by the National Center for Education Statistics in spring 2011, the scores for kindergarten entry were higher for delayed-entry kindergartners and on-time kindergartners than for repeating kindergartners.

"Even though most school districts want the child to be at least at the age of five, the cut-off date for joining differs according to school district and state," said Vela.

There are mixed results on whether redshirting is helpful for the child in the long run. A study conducted by the National Bureau of Economic Research in 2011 said that starting kindergarten one year late "substantially reduces the probability of repeating the third grade, and meaningfully increases in tenth grade math and reading scores. Effects are highest for low income students and males." Alternately, estimates suggest that entering kindergarten early may also have detrimental effect on future outcomes.

Redshirting poses challenges not only to children but to teachers and parents.

"The teacher is mostly impacted by it. They are dealing with children of ages ranging between four and a half and six and a half. This is a large developmental gap when trying to get through the state standard curricula," said Vela.

"The student will develop a persona that they are always bigger, better, and have the upper hand, which might be challenging in their future," she said.

Tracy Gibb, a mother, blogger of Less than Perfect, deliberately redshirted her son because she thought he was emotionally immature. Her son, now 13, has a best friend one year younger than he is.

"When he complains about his friend, I always try to remind him that he is one year younger than him and that he was doing the same things last year," Gibb told ABCNews.com.

Gibb still thinks she made the right choice not only because her son was "emotionally immature," but also because she did not want him to join high school or college at a very young age. "If he's older, he won't be easily manipulated into drug use and malpractices like this. He might feel more confident dealing with older students," she said.

Just as Gibb made a choice depending on her son's emotional needs, Vela recommends that parents do the same.

"Parents make that decision for all kinds of different reasons. We can test a child academically but we can never test their emotional readiness. They sometimes are not ready to leave home at the age of five and the separation anxiety will impact them for a long time. You also find children who are ready to leave home at an even younger age. So it's really up to the parent to decide for their child," said Vela.