If you want a baby who will grow up to become a star student, this might help: wait at least two years before giving your child a sibling.

A study out of the University of Notre Dame has found that when siblings are spaced more than two years apart, the older child fares better at reading and math.

The younger siblings, it should be noted, did not experience similar positive academic gains. However, they also didn't seem to suffer negative academic effects when born well after their siblings.

The researchers -- economist Kasey Buckles and graduate student Elizabeth Munnich -- say part of the reason for their findings could be the amount of attention older children receive in their formative years when the arrival of a little sister or brother is delayed.

"Our results indicate that spacing could be an important channel through which parents can improve child outcomes," the researchers write.

The study will be published in an upcoming issue of the Journal of Human Resources, but it is already making the rounds on the blogosphere.

The researchers point out that numerous studies have examined how the number of siblings in a family or their gender makeup influence educational attainment, IQ scores and future employment.

However, little attention has been devoted to the spacing of siblings.

The pair used data from the 1979 U.S. National Longitudinal Survey of Youth, which includes more than 12,000 respondents, and compared it to test scores from the Peabody Individual Achievement Test, which measures academic achievement in children ages five to 18.

The study noted that a one-year increase in spacing boosts test scores by 0.17 standard deviation (SD), or three times the effect of increasing annual family income by $1,000. In contrast, spacing of less than two years is associated with a 0.58 SD decrease in math scores and a 0.65 SD decrease in reading scores.