Tue Jan 20, 2015 12:07pm EST

Kids' math and reading skills when they start kindergarten can vary greatly based on their social and economic status, according to a new study.
“We knew economic circumstances have an impact on early child development, but it was surprising just how big the reading and math ability gaps really are between children in different socioeconomic status groups by kindergarten entry,” said lead author Kandyce Larson of the American Academy of Pediatrics in Elk Grove Village, Illinois.
Larson and her colleagues studied math and reading test scores for more than 6,000 U.S. kids entering kindergarten in 2006 or 2007.
The researchers used the kids’ household income, parental occupation and education to divide them into five socioeconomic groups.
Kids in the lowest socioeconomic group scored in an average 34th percentile on the reading test, compared to an average 67th percentile for kids in the highest socioeconomic group, according to results in Pediatrics.
Average math percentiles were 33 in the lowest socieconomic group, compared to 70 in the highest group.
Compared to kids in the higher socioeconomic bracket, those in the lowest tended to have younger mothers, lower average family reading scores, fewer books in the home, and were less likely to have rules about bedtime, food and chores.
These types of home-life factors explained about half of the differences in the kindergarteners' reading and math ability, the researchers write.
“Families with higher incomes are able to provide a cognitively stimulating environment for their children as they can purchase educational toys, books, and offer variety in the child’s life such as bringing them to museums, as well as purchasing better quality food which will also help their development,” said Orla Doyle, a lecturer in the school of economics at the University College Dublin Geary Institute for Public Policy.
“However, income is also a marker for underlying characteristics within the family,” said Doyle, who was not involved with the new study. “Parents with higher incomes typically have more desirable (traits) such as higher IQ, motivation, persistence, and consciousness,” she told Reuters Health by email.
Almost all the parents in the highest socioeconomic group expected their four-year-old child to earn a college degree someday, while only 57 percent of parents in the lowest group expected the same.
Parents who plan to send their children to college may establish early routines and practices to reach that goal, Larson said.
She pointed out that access to high-quality preschools, books and home computers is not equal across the socioeconomic spectrum. Neither is knowledge about the importance of early reading.
“The good news," Larson wrote in an email, is that modifiable factors, like parent reading and preschool attendance, may improve children's outcomes.
The first five years of life are a critical period for brain development, she said.
“Studies show that cognitive functioning at school entry predicts future educational attainment and health and well-being into adulthood,” Larson said. “This is why it is so important that we intervene early to optimize developmental capacity for all children.”
Interventions targeted at improving the home environment for low socioeconomic families, starting as early as pregnancy, have been effective, Doyle said.
“Home visiting programs target low socioeconomic families and provide regular home visits delivered by trained professionals, and aim to educate parents about child development and promote positive parenting skills,” she said.
Larson cautioned that several other factors may also contribute to the gap in cognitive ability, but were not measured in this study.
For example, she said, low-income parents may experience obstacles, such as inflexible work schedules that interfere with family routines and participation in childhood programs.
They also did not have information on parental intellectual ability, she noted.