NEW YORK (Reuters Health) - A mother's drug use may have far-reaching consequences, eventually affecting the self-esteem of her grandchildren, new research suggests.

In a study of three generations of urban, minority families, researchers found that children whose grandmothers had a history of drug abuse tended to have poorer self-esteem than their peers.

The connection appeared to be explained by the second generation. That is, women whose mothers abused drugs had a more troubled relationship with their own children.

"This study suggests that mothers' drug problems are not just near-term risks for their children, but also pose long-term risks for their children's future functioning as parents and thereby for their grandchildren," the study authors report in the journal Pediatrics.

Dr. Judith S. Brook of New York University School of Medicine led the research.

The findings are based on interviews with 149 New York City children ages 7 to 12, their mothers and grandmothers. The researchers found that when grandmothers had a history of drug abuse, their daughters tended to have more conflicts with and negative feelings toward their own children.

Their children, in turn, had lower feelings of self-worth compared with their peers.

The findings suggest that poor parenting skills are being passed down through the generations of drug-affected families, according to Brook's team.

This implies that addressing "future grandmothers'" drug problems could have positive effects on multiple generations, they conclude.

"Improving grandmothers' parenting skills and preventing or intervening to reduce grandmothers' drug use," the researchers write, "may well have effects on their own behavior, their children's behavior, and the development of their grandchildren."