Early signs at pregnancy and birth may predict the development of attention deficit hyperactivity disorder (ADHD) in children, a new study has revealed.

Experts from Ireland's RCSI University of Medicine and Health Sciences identified 17 factors that are particularly strong in identifying children with a higher likelihood of developing ADHD.

ADHD is the most common neurodevelopmental disorder in childhood characterized by impulsive behavior, difficulty in paying attention and hyperactivity. The chronic condition that affects millions of children worldwide often continues into adulthood.

In the U.S., 11% of children between the ages of two and 17 have been diagnosed with the condition, while 7.2% of children worldwide live with it.

Based on the signs, there are three types of ADHD:


According to American Psychiatric Association's diagnostic tool, a child with at least six of the following nine behaviors have inattentive ADHD:

  • Difficulty in paying attention to details or making careless mistakes
  • Trouble remaining focused on tasks and activities
  • Having a short attention span and getting easily distracted
  • Trouble following instructions
  • Difficulty with organizing tasks and activities
  • Avoiding tasks that are tedious or time-consuming
  • Losing things frequently
  • Easily distracted by outside stimuli
  • Forgetful in daily activities


When a child has six of the nine symptoms and those symptoms pose problems in daily activity, they are diagnosed with hyperactive ADHD.

  • Frequent fidgeting, tapping hands or feet, or squirming
  • Difficulty sitting still when expected to remain seated
  • Running or climbing when it is not appropriate
  • Trouble playing in calm or quiet surroundings
  • Excessive physical movement
  • Excessive talking
  • Speaking out answers before questions are completed
  • Difficulty to wait for their turn
  • Interrupting conversations or games

Combined ADHD

Children who show behaviors from both inattentive and hyperactive/impulsive categories are diagnosed with combined ADHD.

The exact cause and risk factors for ADHD are unknown. However, studies have shown that genetics plays an important role in developing the condition. Other factors that can cause ADHD:

  • Brain injury
  • Premature birth
  • Low birth weight
  • Prenatal exposure to alcohol or nicotine
  • Exposure to environmental toxins such as lead during pregnancy and childhood

"We know that certain events during our time in the womb can have long-lasting consequences for our health. But not many studies have tried to quantify just how useful prenatal information could be in predicting childhood ADHD symptoms. We focused on readily available information about pregnancies and births, the kind that would be in antenatal records," co-lead researcher Dr. Niamh Dooley, from the RCSI Department of Psychiatry, said in a news release.

The researchers evaluated data from around 10,000 children in the U.S. based on 40 factors that were known at the time of birth such as the sex of the child, the parents' age, complications during the pregnancy or delivery and the baby's exposure to factors such as cigarette smoke.

Out of all these factors available at the time of birth, 17 were found to be particularly good at predicting the number of ADHD symptoms in childhood. The findings of the research were published in the journal Development and Psychopathology.

"Factors that stood out in the study as being useful in predicting ADHD symptoms in childhood included being male, as well as exposure to factors when in the womb such as cigarette smoke, recreational drugs, and the mother having urinary tract infections or low levels of iron," the researchers noted.

Although the study couldn't predict ADHD based on birth information alone, the findings are useful in identifying "which children are most in need of support, particularly when combined with other factors like genetics or family history and the early life environment."

Attention deficit hyperactivity disorder (ADHD)
Attention deficit hyperactivity disorder (ADHD) L21MediaStudio / Pixabay