Babies born before 39 weeks may have a higher risk of developing ADHD, study finds

Babies born before 39 weeks are more likely to develop symptoms of attention-deficit/hyperactivity disorder (ADHD) later in childhood, a new study finds. But the link between early term birth and ADHD symptoms doesn’t mean your baby definitely will have the disorder.

A team from Rutgers Robert Wood Johnson Medical School looked at babies born between 37 and 41 weeks. Of them, the infants born before 39 weeks (considered “early term”) were more likely to experience ADHD symptoms at age 9. Previous research has shown links between ADHD and children born before 37 weeks.

The study in the Journal of Pediatrics used reports from teachers, parents and doctors. This gave researchers a better glimpse into behavior in multiple settings, which can aid in diagnosis, says Nancy Reichman, PhD, lead author of the study. 

Related: Your kid has ADHD—and these 11 superpowers

Observing correlations between early-term birth and ADHD

Dr. Reichman’s team evaluated reported ADHD symptoms in about 1,400 children from birth to age 9. The kids were part of the Fragile Families and Child Wellbeing study, which randomly sampled births in 75 hospitals in 20 U.S. cities between 1998 and 2000.  

Children who were born between 37 and 38 weeks had higher scores on teacher-rated behavioral scales compared to those who were born between 39 and 41 weeks.

Babies are considered to be born full-term anytime after 37 weeks, whereas delivery prior to 37 weeks is considered preterm.

• At 37 weeks, the pregnancy is considered early-term (technically full-term, but on the early side of it)
• At 41 weeks, the pregnancy is considered late-term
• At 42 weeks, the pregnancy is considered post-term

The big takeaway: The researchers found a correlation between the longer a child stays in the womb and a lower potential risk for ADHD symptoms. Each week of gestational age at term was associated with 6% lower hyperactivity scores and 5% lower ADHD and cognitive problems or inattention scores. 

Being born at 37 to 38 weeks was linked with 23% higher hyperactivity scores and 17% higher ADHD scores when compared to children born at 39 to 41 weeks.

“The findings add to growing evidence supporting current recommendations for delaying elective deliveries to at least 39 weeks and suggest that regular screenings for ADHD symptoms are important for children born at 37 to 38 weeks,” Dr. Reichman says in a statement.

Related: 8 common myths about ADHD debunked

Understanding ADHD

What puts children at a lower gestational age at a higher risk for ADHD? Dr. Reichman tells Motherly that she believes it’s due to brain development. That is, babies who are on the early side of full-term may miss out on late-stage brain development, while those who stay in longer benefit from more development time.

“This increased risk is likely related to the reduced time for brain development when those final weeks in utero are missed, though we also know that developing ADHD has many factors associated with it,” notes Kate Hanselman, a psychiatric-mental health nurse practitioner in Connecticut. She was not affiliated with the research.

Related: ADHD & Autism diagnoses are on the rise—but so is support for kids

What causes ADHD?

The researchers found a correlation, but it’s also important to note that ADHD does not have one specific cause. Family history, genetic predisposition, factors affecting brain development in utero including gestational age and maternal exposures while pregnant, plus environmental exposures in childhood and more can all play a role, Hanselman says.

Dr. Reichman believes the mechanism for developing ADHD may be the same in children born earlier compared to those born later who still go on to develop the disorder. “It is likely a combination of factors [that leads to ADHD],” she says. But the risk may just be less when a child is born at a higher gestational age, Dr. Reichman adds.

“Each week of gestational age is important, at least through 39 weeks,” Dr. Reichman says. 

What should you do if your bundle of joy was born earlier, or is expected to be? Have your child screened regularly, and know what to look for, Dr. Reichman notes.

Symptoms of ADHD

According to the National Institute of Mental Health, symptoms of ADHD can include:

• Inattention, including missing details and making mistakes
• Difficulty sustaining attention 
• Not seeming to listen when spoken to directly
• Difficulty following through on instructions or completion of tasks
• Difficulty organizing tasks and activities
• Avoiding tasks that require sustained mental effort 
• Misplacing objects necessary for tasks or activities
• Being easily distracted 
• Fidgeting and squirming while seated, or leaving seat when expected to stay
• Running, dashing or climbing at inappropriate times
• Difficulty engaging in hobbies or playing quietly
• Be constantly in motion or on the go
• Excessive talking
• Asking questions before being asked or speaking without waiting for a turn
• Interrupting others

ADHD symptoms can appear as early as between 3 and 6 years old. Symptoms can also change over time.

ADHD: What to look for

Parents should know that there are three different presentations of ADHD: inattentiveness, hyperactivity, and a combination of both.

“It’s critical for parents to understand the breakdown of these presentations, as one child’s ADHD symptoms and diagnosis may differ from another,” says Kristin J. Carothers, PhD, a psychologist based in New York and Atlanta. (She contributes to Understood.org, a nonprofit that supports people who learn and think differently.)

To determine if your child has ADHD, reach out to a developmental pediatrician, clinical psychologist, or psychiatrist. They are all trained in ADHD assessment and diagnosis. 

You may want to work with a neuropsychologist to better understand more about executive functioning or the way a child’s ADHD symptoms might impact their learning or social interactions, Dr. Carothers tells Motherly. 

Medication is usually the quickest way to reduce symptoms, but that “doesn’t necessarily mean it’s a one-size-fits-all approach, or something that every child with ADHD requires,” Dr. Carothers notes. 

Related: Meet the first FDA-approved video game to treat kids’ ADHD

Consistent routines and praise for on-task behavior can also work well. Parent Management Training (PMT) can help adults learn skills to help their child, Dr. Carothers explains. 

If a child is also experiencing some underlying anxiety concerns or having difficulty with decision making, they may benefit from cognitive behavioral therapy (CBT), she adds.

If your child was or may be born early or pre-term, it doesn’t mean they will have ADHD, Dr. Hanselman emphasizes. 

“Our medical care and technology to support early-term and preterm babies is excellent today, as is the care to support early-term and preterm kids’ needs as they grow into adults,” Dr. Hanselman adds.