TUESDAY, Sept. 4, 2012 (HealthDay News) -- New research suggests how smoking during pregnancy may increase a child's risk of obesity during adolescence.
Children born to mothers who smoked while pregnant show structural changes in their brains, which make them more partial to fatty foods and prone to subsequent weight problems, the study found.
"The fact that prenatal smoking is associated with a high risk of obesity in offspring has been known, but the potential mechanism that may lead to this risk was not fully understood," said study author Dr. Zdenka Pausova, a scientist at the Hospital for Sick Children in Toronto. "Our study suggests that maternal smoking may cause structural changes in the part of the brain that processes reward and may increase preference for fatty food."
Still, more study is needed to validate the findings, she said. Not all mothers who smoke are destined to have obese children, she added. Smoking during pregnancy is one of many factors that may tip the scales in favor of teenage obesity.
The new study, published online Sept. 3 in the Archives of General Psychiatry, included 378 adolescents aged 13 to 19. Of these, 180 kids had mothers who smoked more than one cigarette a day during the second trimester of pregnancy. The average was 11 cigarettes a day.
As expected, babies born to mothers who smoked weighed less at birth. They also tended to be breast-fed for shorter periods of time, and were more likely to weigh more as teens than their peers whose moms did not smoke while pregnant.
What's more, scans showed that teens whose mothers were smokers during pregnancy had a significantly lower volume in the reward center of the brain, the amygdala.
When the researchers assessed the participants' dietary fat intake, they found an inverse correlation between amygdala volume and fat consumption, meaning the more fat consumed, the lower the amygdala volume.
Dr. Lorena Siqueira, director of adolescent medicine at Miami Children's Hospital, said the new findings provide one more reason that mothers-to-be should not smoke. "We have known that smoking during pregnancy increases the risk for low birth weight babies and preterm delivery," she said.
Calling the findings "fascinating, but preliminary," she said that maternal smoking history may not be the sole reason why some teens crave fatty foods. "This needs to be looked at more as a lot of what we are seeing may be due to access to salty, fatty foods that we all have a taste for."
Patricia Folan, director of the Center for Tobacco Control at North Shore-Long Island Jewish Health System in Great Neck, N.Y., said this new information may help experts tailor quit-smoking messages toward some pregnant women.
"We often counsel these women and tell them that smoking during pregnancy may increase their risk for a low birth weight baby, but they may not appreciate this," Folan said. Risk of adolescent obesity may resonate more for some women. "We know if we personalize the message, it can help motivate them to make a quit attempt," she said.
About 10 percent of pregnant women in the United States and Canada smoke, according to background information in the study.
It's never too late to quit smoking when pregnant, Folan said. "The pregnancy will be improved and you will be more likely to deliver at term without the health risks associated with preterm birth," she said.
More tools are available today to help people quit smoking than ever before, she said. "Talk to your doctor about which method will be best for you," she added.
While the study found an apparent link between maternal smoking and fatty food cravings in teens, it didn't prove the existence of a cause-and-effect relationship.
The American Cancer Society provides information on how to quit smoking for good.