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Smoking Moms Raise Diabetes Risk for Kids

Habit may alter fetal metabolism for life

FRIDAY, Jan. 4, 2002 (HealthDayNews) -- There's now more reason than ever for expectant moms to go cold turkey on cigarettes.

New research suggests that children born to mothers who smoked during pregnancy are more likely to become obese and develop Type II diabetes later in life.

And while an expert in maternal and fetal health cautions the findings must be confirmed in future studies, he says it should remind expectant mothers of the harm smoking already poses to a fetus.

In tomorrow's issue of the British Medical Journal, researchers at the Karolinska Institute in Stockholm studied data collected from 17,000 British births that took place between March 3 and 9, 1958. The midwives present at the birth recorded whether the mother had smoked after the fourth month, which is a reliable indicator that a woman will continue to smoke throughout her pregnancy.

The children born were given medical exams at ages 7 and 16, and the mother's smoking habits were again recorded in 1974. Finally, a follow-up when the children were 33 listed whether they had developed Type II diabetes.

Scott M. Montgomery, who led the study, found that 602 people -- roughly 10 percent of the children who stayed in the study until they were 33 -- became obese.

Fifteen men and 13 women whose mothers had smoked more than 10 cigarettes a day during their pregnancy developed Type II diabetes by the time they turned 33, a fourfold increase compared to children whose mothers hadn't smoked. The children who grew up and started smoking by the age of 16 faced a threefold increase in their risk of diabetes.

"It makes sense in an evolutionary perspective," says Montgomery. If a mother smokes, he says, it interferes with the blood supply to the placenta that nourishes the growing fetus.

"If a fetus is led to believe that it's growing up in a time of famine -- which is exactly what would happen if a mother smoked -- it's going to prepare the child's body to conserve energy," he says.

"When that child is born, its metabolism has set up to conserve a lot of energy, which of course in today's high-calorie, low-exercise world is entirely inappropriate," he says. "This combination of being set up to conserve fat, and then being bombarded by calories throughout life is a much greater risk for obesity and Type II diabetes."

Montgomery says these findings could provide clues to the causes of obesity, insulin resistance and Type II diabetes, and he stresses this is another argument against smoking while pregnant.

"It's a terrible act of selfishness," he says. "You may be setting your baby up to suffer from quite significant chronic diseases which may not actually show themselves until the child himself is an adult."

Keith M. Godfrey, a clinical scientist of maternal, fetal and neonatal physiology at the University of Southampton in England, is familiar with the study.

"These findings necessarily have to be regarded as preliminary and in need of replication, but nonetheless are interesting and reinforce the message that smoking during pregnancy should always be strongly discouraged," he says.

He says other studies had not examined the effect of maternal smoking on diabetes and obesity, looking instead for markers such as impaired blood sugar tolerance or raised blood pressure in the offspring. Godfrey notes other research has shown maternal smoking has a negative impact on bone growth and development in children.

What To Do: For more information about the dangers of smoking while pregnant, read the Women and Smoking - A Report of the Surgeon General 2001, from the Centers for Disease Control and Prevention, visit the American Lung Association or check out the BabyZone.

SOURCES: Interviews with Scott M. Montgomery, Ph.D., principal research fellow, Karolinska Institute, Stockholm, Sweden; Keith M. Godfrey, Ph.D., clinical scientist, honorary consultant, Medical Research Council Environmental Epidemiology Unit, University of Southampton, Southampton, England; Jan. 5, 2002, British Medical Journal
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