Researchers examined data from 12 previous studies with a total of
1,787 participants and found that even among these high-risk babies,
the odds of ADHD increased as babies spent fewer months in the womb
and were born at even tinier sizes.
“There is robust evidence that very preterm or very low birth weight
individuals have an increased risk of ADHD,” said senior study
author Dr. Carlos Renato Moreira-Maia of the Federal University of
Rio Grande do Sul in Porto Alegre, Brazil.
It’s possible that the stress of the early birth or premature
development of vital organs and systems in the body might lead to
inflammation and hormonal changes that contribute to ADHD,
Moreira-Maia said by email.
Many factors including mothers’ medical histories as well as
smoking, eating and drinking habits during pregnancy can influence
the odds of preterm birth or an underweight infant, and these things
might also contribute to ADHD in kids, Moreira-Maia added.
“The reasons for increased vulnerability to ADHD in preterm/low
birth weight individuals remain unknown,” Moreira-Maia said.
Pregnancy normally lasts about 40 weeks, and babies born after 37
weeks are considered full term. The study focused on the most
vulnerable preterm infants, delivered before 32 weeks' gestation or
weighing less than 1,500 grams (3.3 pounds) at birth.
In the weeks immediately after birth, preemies often have difficulty
breathing and digesting food. They can also encounter longer-term
challenges such as impaired vision, hearing and cognitive skills, as
well as social and behavioral problems.
For the current study, researchers looked at data on healthy babies
who were born weighing at least 2,500 grams (5.5 pounds) or arrived
after 37 weeks' gestation and they also considered smaller, earlier
arrivals.
Compared with these healthy babies, infants born at less than 32
weeks' gestation or weighing less than 1,500 grams (3.3 pounds) were
more than twice as likely to develop ADHD, researchers report in
Pediatrics.
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When babies were born at less than 28 weeks' gestation or weighing
less than 1,000 grams (2.2 pounds) their odds of ADHD were more than
four times higher than healthy infants, the study also found.
One limitation of these results is that all but one of the smaller
studies in the analysis was done in a high-income country, which
means the results may not reflect what might happen in lower-income
nations, the authors note.
Even so, the findings offer fresh evidence of the connection between
an ADHD diagnosis and starting life too early or weighing too
little, said Joel Nigg, author of an accompanying commentary and
director of the ADHD and Attention Disorders Program at Oregon
Health and Science University in Portland.
Women, in high-income countries where malnutrition isn’t a concern
can help to minimize their odds of having a preterm or underweight
baby by doing several things during pregnancy, Nigg advised. These
include eating well, gaining a healthy amount of weight, not
smoking, avoiding stress and getting enough sleep.
When they do have preemies or underweight babies, women may still be
able to minimize the chances of ADHD by breastfeeding infants as
long as possible and making sure babies get plenty of calories, Nigg
said.
“If you have a low birth weight or pre-term baby, follow medical
advice,” Nigg said by email. “But the first principle is nutrition,
nutrition, nutrition.”
SOURCES: http://bit.ly/2kdFay6 and http://bit.ly/2CXClZL Pediatrics,
online December 18, 2017.
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