An interviewer assed their behavior at the age of 3 years, and then again when they were 5, by examining a caregiver-reported Child Behavior checklist
. The interviewer taught the caregivers how to complete the checklist.
The researchers found that the exposed children had a higher risk of developing some behavior problems. They factored out potential confounders, such as exposure to marijuana, alcohol, and tobacco, as well as a number of environmental risks.