The children of women who smoked while pregnant may be more likely to be obese in their late teenage years, a study showed today.

Researchers found that those who were exposed to cigarette smoke while in the womb had significantly higher quantities of fat than their non-exposed peers once they reached late adolescence.

The exposed teenagers had 33% more intra-abdominal fat and 26% more subcutaneous fat, according to the international team that carried out the study.

Intra-abdominal fat surrounds internal organs, while subcutaneous fat is found directly under the skin.

Zdenka Pausova, one of the study’s two principal investigators, said the findings provide another reason for expectant mothers to avoid smoking.

She said: “We believe that maternal cigarette smoking during pregnancy plays an important role in the fetal programming of obesity.

“Although we do not know the exact mechanisms, we know that nicotine in cigarette smoke, for example, sets into the baby’s body and stays there in higher quantities and for longer than in the mother’s.

“Animal studies suggest that nicotine given prenatally could influence certain parts of the brain, including those that control how much and what we eat and how well we burn calories.”

The scientists studied more than 500 teenagers between the ages of 12 and 18, half of whom were exposed to maternal cigarette smoke. Those who were exposed weighed about 300 grams less at birth than their peers, were breast-fed for a shorter period of time and were exposed more frequently to second-hand smoke in-utero.

Magnetic resonance imaging was used to measure the two types of fat and the teenagers were interviewed by a nutritionist to track their daily energy and nutrient intake and asked to complete questionnaires about their physical activity.

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The Press Association