Overall, there is an ongoing debate as to whether it is more beneficial for boys and girls to be “redshirted” (a sports term in which college freshman are held back from participation to allow a year to gain strength).
Relatively younger children perform 4 to 12 percentiles less well in third and fourth grade and 2 to 9 percentile worse in seventh and eighth.
Relatively older students are 7.7 percent more likely to take the SAT or ACT, and are 11.6 percent more likely to enroll in four-year colleges or universities.
Relative age (how old the child is in comparison to his classmates) is more important that absolute age (how many days the child has been alive) in shaping performance academically.
The most recent 2008 national survey of preschool-aged children found that a higher percentage of boys than girls (9 percent vs. 4 percent) had parents who planned to delay their entry into kindgarten.
There is relatively little research that separates the academic achievement of boys and girls who are redshirted, but many experts speculate that the high rates of bored, disengaged, and ADHD-diagnosed boys may be related to the different patters of maturation for boys and girls.
Sources: K. Bedard (2006). “The persistence of early childhood maturity: International evidence of long-run age effects”; E. Weil (2007). “When should a kid start kindergarten”; National Center for Education Statistics (2007). “Parents’ reports of the school readiness of young children from the National Household Education Surveys Program of 2007”; L. Sax (2008). “Boys and elementary school”.