In today's Health Matters, spanking may pose serious risks to a child's long-term development.

Two Canadian child development experts analyzed two decades of research on children and spanking. They found physical punishment to be associated with higher levels of aggression against parents, sibling, peers and spouses.

While studies show spanking has declined in the U.S. since the 1970s, many parents still believe it's an acceptable form of punishment.

Study authors are urging physicians to help parents learn nonviolent effective approaches to discipline. Findings appear in the "Canadian Medical Association Journal."