Found this via Best Evidence in Brief:

A recent paper  in the Education Researcher has found that children’s preschool mathematical knowledge and, even more so, their early mathematical progress, are significant predictors of later achievement.

The study looked at the mathematics achievement of children from age 4½ to 15. The researchers found substantial, statistically significant associations between preschool mathematical ability and adolescent mathematics achievement, even after controlling for general cognitive developmental levels and a host of relevant demographic, parental, and child variables. Furthermore, they tested the association between early gains in mathematical skills (between age 4.5 and first grade/Year 1) and later achievement. These gains in early mathematical knowledge were even more predictive of age 15 mathematics achievement than preschool knowledge.

The study used data from the National Institute of Child Health and Human Development (NICHD) Study of Early Child Care and Youth Development (SECCYD). The full sample of the NICHD SECCYD data set includes 1,364 children born in 1991 in 10 urban and rural areas across the United States.