Lead author David Kerr, assistant professor of psychology at Oregon State University, and colleagues assessed more than 200 at-risk boys annually from the age of 12 to 31 in how their crime, tobacco, alcohol and marijuana use changed over time.
"These decreases were in addition to the general tendency of boys to engage less in these types of behaviors as they approach and enter adulthood," Kerr said in a statement. "Controlling for the aging process, fatherhood was an independent factor in predicting decreases in crime, alcohol and tobacco use."
However, the study, published in the Journal of Marriage and Family, also found men who were well into their 20s and early 30s when they became fathers showed greater decreases in crime and alcohol use, compared to those who had their first child in their teens or early 20s.
Men who had children at a more developmentally expected time could have been more able or willing to embrace fatherhood and shed negative lifestyle choices, Kerr said.
"This research suggests that fatherhood can be a transformative experience, even for men engaging in high risk behavior," Kerr said. "This presents a unique window of opportunity for intervention because new fathers might be especially willing and ready to hear a more positive message and make behavioral changes."