A recent study found children with ADHD were more likely to have experienced insufficient oxygen supply when they were born. They could have not gotten enough oxygen either before, during or after birth.
Several factors can cause this, such as pre-eclampsia, problems with the placenta or respiratory distress. The link to ADHD was not very large for the babies born at term. It was a little higher for premature babies.
"Attend all prenatal appointments."
The study, led by Darios Getahun, MD, PhD, from the Department of Research and Evaluation at Kaiser Permanente Southern California in Pasadena, looked at certain pregnancy health conditions and the risk of children developing attention deficit hyperactivity disorder (ADHD).
The researchers looked at 308,634 children between the ages of 5 and 11 and then investigated their mother's medical records for different pregnancy complications.
They focused on "ischemic-hypoxic conditions" during pregnancy, which refers to situations in which not enough oxygen is reaching all the tissues of an unborn baby. A total of 13,613 of the children, or 4.3 percent of the total, had been diagnosed with ADHD and were taking two or more prescriptions related to ADHD.
For the study comparisons, the researchers matched each child with ADHD to five children of the same age without ADHD. The primary differences in demographics between the groups were that the children with ADHD were more likely to be boys and to be African-American than the children without ADHD.
The researchers found that the mothers of children with ADHD were more likely to have had a pregnancy condition that could have limited oxygen to the baby than mothers of the children without ADHD.
The increase in risk was small. Children with ADHD born between 34 and 36 weeks of pregnancy were about 20 percent more likely to have had moms with these oxygen-limiting pregnancy conditions.
Children with ADHD born at term (37 to 42 weeks) were only 10 percent more likely to have moms with these pregnancy conditions.
Preemies, however, were more likely to have been born in the midst of these pregnancy conditions. The children with ADHD who were born between 28 and 33 weeks were 60 percent more likely to have had moms with these pregnancy conditions.
The specific pregnancy or birth conditions that were most associated with ADHD in the children were pre-eclampsia, respiratory distress syndrome in the newborn and "birth asphyxia."
Birth asphyxia means the baby did not get enough oxygen before, during or after being born. There are various ways this could happen. The mother could have low blood pressure or the umbilical cord could be compressed, decreasing blood flow.
It's also possible that problems with the placenta might lead to birth asphyxia. Sometimes low oxygen levels in the mother's blood from heart or respiratory problems or from anesthesia could contribute to birth asphyxia.
The study was published December 10 in the journal Pediatrics. The research was funded by Kaiser Permanente Direct Community Benefit Funds. The authors declared no conflicts of interest.