A study published in this week's Pediatrics finds that infants who experienced oxygen deprivation in utero are at an increased risk of developing attention-deficit (hyperactivity) disorder in childhood.
Prenatal exposure to oxygen deprivation conditions, known as ischemic-hypoxic conditions, can result from birth asphyxia, neonatal respiratory distress syndrome and preeclampsia.
Researchers went through the medical records of nearly 82,000 children between the ages of 5 and 11 and found that children who had experienced those conditions were 16% more likely to be diagnosed with ADHD later in childhood.
According to the Centers for Disease Control, 8.4% of children between the ages of 3 and 7 have been diagnosed with ADHD, and boys are more likely than girls to have it. Annually, the CDC estimates ADHD-related illness in children to cost between $36 billion and $52.4 billion.
Dr. Darios Getahun, lead author of the study, said that although there may not be any interventions aside from monitoring a mother and her child through pregnancy, knowing these factors can better assist physicians in tracking and diagnosing ADHD in children.
Getahun, who works with the Kaiser Permanente Department of Research and Evaluation, added, "The study leads us to suggest that those children that are exposed, they are at risk. And it's important to closely monitor these children as early diagnosis and treatment is most important."
When looking at specific factors, children who had exposure to neonatal respiratory distress syndrome had a 47% greater risk of developing ADHD, followed by children whose mothers had preeclampsia, or high blood pressure during pregnancy, with a 34% greater risk. Children who had been exposed to birth asphyxia - when a baby doesn't receive enough oxygen at birth - carried a 26% greater risk of developing ADHD.
Researchers also found that the risk of ADHD was increased if the risk factors were present and the birth was preterm.
However, Getahun and researchers were quick to also note that the percentage of ADHD cases attributed to ischemic-hypoxic conditions is small -- just about 3% - and said that rather on focusing on preventing such conditions, these factors were a tool.
"Our findings could have important clinical implications. They could help physicians identify newborns at risk that could benefit from surveillance and early diagnosis, when treatment is more effective," Getahun said. "We suggest future research to focus on pre- and postnatal conditions and the associations with adverse outcomes, such as ADHD."