CNN)The American Academy of Pediatrics has hardened its stance against spanking children as a form of parental discipline.
In a new policy statement, published in the journal Pediatrics on Monday, the pediatricians' group recommends that adults caring for children use "healthy forms of discipline" -- such as positive reinforcement of appropriate behaviors, setting limits and setting expectations -- and not use spanking, hitting, slapping, threatening, insulting, humiliating or shaming.
The policy statement updates guidance published in 1998 that recommended "parents be encouraged and assisted in developing methods other than spanking in response to undesired behavior."
"In the 20 years since that policy was first published, there's been a great deal of additional research, and we're now much stronger in saying that parents should never hit their child and never use verbal insults that would humiliate or shame the child," said Dr. Robert Sege, first author of the policy statement and a pediatrician at the Floating Hospital for Children at Tufts Medical Center in Boston.
"This is much stronger than the previous advice," he said. "The new policy encourages pediatricians to discuss the data about different kinds of discipline with parents so, of course, they can make their own decisions in how they chose to raise their children."
The policy statement describes corporal punishment as "noninjurious, open-handed hitting with the intention of modifying child behavior" and indicates that spanking is considered a form of such physical punishment.
The statement goes on to describe how several studies have found associations between spanking and aggressive child behavior, depressive symptoms in adolescence and less gray matter in children's brains, among other outcomes.
How to discipline without spanking
The statement encourages pediatricians to counsel the parents of their patients when they may want guidance about the use of spanking. Sege said there are other forms of discipline that parents can employ, no matter their child's age.
For instance, for children younger than 1 who might be misbehaving, "the best thing to do is just pick them up and move them somewhere else, distract them, change the subject -- and that's usually all they need and they can handle it," he said. "Your average 6-month-old child doesn't have the ability to learn the rules. They will eventually."
For toddlers and preschoolers, Sege recommended using the time-out method, which involves a child sitting quietly by him- or herself.
"What we talk to parents about is paying attention to your child's good behavior and paying less attention when they're misbehaving," Sege said.
"Kids like attention, they crave that, and if they misbehave, we recommend something called a time-out," he said. "If they're 2 years old, you have to ignore them for two entire minutes."
For older children, Sege said, typically allowing the natural consequence of misbehavior play out can be effective.
"So if they run out in the street, you don't want the natural consequence to be that they get run over by a car. But a natural consequence might be that they have to hold your hand when they're in the street or they can't go out on their own past a busy street until you've observed them always looking both ways," Sege said.
In other words, holding Mom's or Dad's hand becomes the consequence.
All in all, "the loving relationship between a child and their parents is the most important relationship that there is," Sege said.
"Parents can use that relationship to teach their children right from wrong without inserting violence, shame and humiliation into that relationship," he said. "As a result, children are more likely to grow up feeling secure and positive, knowing how to regulate their own behavior."
The science on spanking and child development
The policy statement is consistent with what research has found on the relationship between corporal punishment and adverse outcomes among children, said Rebecca Ryan, a developmental psychologist and associate professor at Georgetown University who was not involved in the statement.
Yet Ryan, who has studied the use of corporal punishment, noted that only a correlational relationship has been found, not a causal one.
"Nobody has randomly assigned children to receive different types of parenting or different types of discipline strategies, per se. ... So it's difficult for anybody to say spanking a child causes that child later on to be more aggressive, even though there are theories to suggest that could be why the correlation exists," Ryan said.
"Although all the evidence is correlational, there's little correlational evidence that it's an effective strategy, and if it were effective,
Since research shows only a correlational relationship, some question whether children who are more aggressive or misbehave more are subsequently spanked more -- and could that be why corporal punishment has been linked with higher levels of behavioral problems among children?
"There probably is reverse causation, but one of the things that some of the longitudinal research suggests is that when you look at kids over time -- so controlling for baseline rates of misbehavior -- children who are disciplined with corporal punishment versus those who are not, who have the same kinds of behavior problems, show increases in behavior problems over time in a way that children who aren't disciplined that way don't," Ryan said.
"So yes, there is probably some truth to the idea that kids who are predisposed to misbehavior for whatever reason are more likely to be spanked by parents who use that form of discipline than kids who are less likely to misbehave for whatever reason," she said. "But it's also true that spanking is correlated with an increase in behavior problems over time among children with similar levels of misbehavior relative to nonphysical forms of discipline."