When it comes to social skills, language and cognitive development, children whose mothers or grandmothers gave birth in their teens lag behind their peers, according to the findings of a new study using Canadian data.

Previous studies have established that children born to adolescent mothers are less ready for school and have poorer educational outcomes than kids born to older mothers, according to the report by Elizabeth Wall-Wieler of Stanford University in California and colleagues at the University of Manitoba. Teenage motherhood has such a significant impact on childhood development that it can affect the woman’s grandchildren decades later.

Compared with children whose grandmothers were 20 or older at the birth of their first child, a greater percentage of children whose grandmothers had been teen moms were not ready for school, the study found.

The relationship persisted even when a child’s mother was not an a teen mom.

“I was surprised to find that if a child had a mother who was not an adolescent, but whose grandmother had her first child before age 20, was less ready for school than a child whose mother and grandmother had both been at least 20 when they had their first child,” study author Elizabeth Wall-Wieler told CTVNews.ca in an email.

Children whose grandmothers were teen moms but whose mothers were older, had 39 per cent greater odds of not being ready for school compared with kids whose moms and grandmothers were both at least 20 at the birth of their first child, according to the report.

These youngsters lagged behind in physical well-being, social competence, language and cognitive development, the report authors said.

The mechanisms underlying this are unclear, the authors said, but the results have policy implications for school readiness as well as calculating the costs and consequences of adolescent motherhood.

It recommended that interventions to improve outcomes for kids born to teen moms be extended to the grandchildren of adolescent mothers.

The study was inspired by Wall-Wieler’s previous research into teenage pregnancy, including several studies that looked at factors influencing early childhood development.

“Based on previous studies, I knew that children of adolescent mothers were less likely to be ready for school, and among adolescent mothers, it was more likely that their mothers were also adolescent mothers,” she explained.

The authors used data from the Manitoba population research data repository to identify 11,326 children born in Manitoba in 2000 through 2006 whose mothers were born in 1979 through 1997.

Kids born in these years took the Early Development Instrument, a 103-item questionnaire administered by kindergarten teachers to assess five areas of development.

The researchers were able to link information from the data repository, EDI scores and Canadian census data.

Results were adjusted to account for differences in birth year and location, income quintile and child’s health at birth.

Although Wall-Wieler said this is believed to be the first study to examine the multigenerational effects of teenage motherhood on school readiness, she noted that the research shows an area of opportunity for evaluating which children may be at risk for falling behind in school.

“When identifying children who may benefit from additional resources to ensure they have they are ready to start school when they enter kindergarten, we should look beyond risk factors in the child’s immediate family and environments,” said Wall-Wieler.

The study was funded by the University of Manitoba.