June 28, 2010 -- Mothers who smoke while pregnant increase the risk that their child will develop psychological problems, a new study finds.
And a related study found that babies exposed to secondhand smoke from fathers or other people may be at increased risk of developing weight problems, even if mothers are nonsmokers.
Both studies appear online in advance of publication in the July issue of the journal Pediatrics.
Researchers from the United Kingdom and Brazil, using data on 509 Brazilian and 6,735 British families, say there is reason to believe that mothers who smoke may expose their fetuses to harmful substances that may affect the behavior and conduct of children in later years.
“There was some evidence that maternal smoking in pregnancy is associated with greater conduct/externalizing problems [aggressive behavior, rule-breaking behavior] in the offspring at the age of 4,” the authors write.
Mary-Jo Brion, PhD, of the University of Bristol, tells WebMD by email that babies exposed to smoke may be prone to rule breaking, such as lying, cheating, bullying, and disobedience.
Maternal smoking seems to be more strongly associated with child problems than is paternal smoking.
No association was found between maternal smoking and childhood development of attention deficit hyperactivity disorder.
“To some extent it is somewhat surprising that ... maternal smoking may also directly impact child behaviors from exposing the fetus to tobacco in utero,” she tells WebMD. “This study suggests that adverse effects on offspring may extend as far as putting children at increased risk of having behavioral problems.”
She says the investigators had “complete information” on mothers, fathers, and their children.
One of the authors of the second study, Mary Schooling, PhD, of the University of Hong Kong, tells WebMD by email that scientists investigated 6,790 children with nonsmoking mothers, of whom 2,165, or 32%, had fathers who smoked. More than half of the fathers smoked daily and 626 occasionally. And 2,674 children were exposed to secondhand smoke from other sources in infancy or before birth.