Is Childhood Obesity Largely Driven by Maternal BMI and Smoking Behaviour?

Countless factors have been implicated in the increase in childhood obesity that has occurred in the past decades. These include increasing sedentariness and  overconsumption of calories. However, data on this is far less consistent or convincing that one would assume.

Lately, considerable interest has focussed on biological factors directly related to fetal and early prenatal development that may set the stage for subsequent weight due to “metabolic programming”.

This notion finds further support in a study by Sheila Williams and colleagues from the University of Otago, Dunedin, New Zealand, published in Pediatric Obesity.

The researchers analysed data from two cohort studies: the Dunedin Multidisciplinary Health and Development Study (DMHDS), that included 974 kids born in 1972–1973 and the Family Lifestyle, Activity, Movement and Eating Study (FLAME), that included 241 kids born in 2001–2002.

Over the 29 years that lie betweeen the two cohorts, kids became significantly heavier as did their moms, whereby the increased BMI of the mothers “accounted” for a substantial proportion of the increase in kids’ weights.

Similarly, although overall rates of maternal smoking reduced by about 15%, kids of mothers who smoked during pregnancy were heavier by age 7 than the kids of moms who didn’t.

Thus, maternal BMI and smoking behaviours turned out to be the most significant predictors of childhood weight gain (while changes in behavioural factors, including sleep and television viewing, appeared to have little effect).

But, as the authors hasten to point out, such studies cannot prove or disprove causal relationships. Nevertheless, these findings are certainly consistent with the notion that maternal influences during fetal development or in early childhood may well predispose offspring to greater weight gain, thereby accounting for a substantial proportion of the childhood obesity epidemic.

@DrSharma
Edmonton, AB

Williams SM, Taylor RW, & Taylor BJ (2013). Secular changes in BMI and the associations between risk factors and BMI in children born 29 years apart. Pediatric obesity, 8 (1), 21-30 PMID: 23001951

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