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Early life factors, such as birth weight, maternal smoking and fathers’ weight, can all predispose a young child to obesity, suggest two European studies.

 

In the first study, conducted in 2374 Greek children aged 1 to 5 years, parents were asked a series of questions about their health and lifestyle, while data were gathered on infant feeding and body weight. The researchers at Harokopio University in Athens found that infants with an abnormally high birth weight (i.e. large for gestational age) were 4.5 times more likely to be overweight at 6 months of age than infants whose birth weight was in the normal range. Risk of overweight was also increased when infants were formula-fed rather than breast-fed, or when mothers were inactive or smoked during pregnancy. Infants with overweight fathers were also more prone to become obese. The researchers called for obesity prevention to be targeted at those children with significant background predictors, such as lack of breast-feeding and parental obesity or smoking.

 

It would seem that maternal smoking and overweight have a long-lasting effect on children’s obesity risk, according to the second study involving a cohort of 6535 Swedish men. Researchers at the Karolinska Institute in Stockholm attempted to correlate factors such as maternal smoking , education and body mass index (BMI) around the time of pregnancy with obesity risk in sons at the age of 18. Mothers’ BMI and smoking were the strongest predictors of their sons’ obesity risk. Where mothers were non-smokers, birth size was an important driver of later obesity in sons.

 

The emphasis on maternal smoking in both of these studies is supported by a recent meta-analysis which considered evidence from 14 observational studies (total sample size = 84,563). Children whose mothers smoked during pregnancy were around 1.5 times more likely to become obese later in life compared with children whose mothers did not smoke during pregnancy. The mechanisms underlying the relationship between maternal smoking and child obesity are unclear.