Piling on the pounds during pregnancy can lead to overweight children and might be contributing to rising obesity rates, research suggests.
A mother’s weight gain directly affects the obesity risk of her children, a study involving more than 40,000 women and their 91,000 offspring has confirmed.
For each kilogram of weight gained during pregnancy, a child’s body mass index (BMI) at age 12 increased by 0.02 kg/m2, the study found.
Children of mothers who put on the most weight had a BMI that was 0.43 higher, on average, than those whose mothers gained the least weight.
This could account for “several hundred thousand annual cases of pediatric overweight or obesity worldwide”, said the researchers.
It is believed that previous research highlighting the trend could have been swayed by shared influences affecting mother and child, such as socio-economic background and genes.
Therefore the US scientists looked at mothers with two or more children, matching birth records to school reports that included every child’s body mass index (BMI) at the age of 12.
Comparing siblings with the same home environment and distribution of obesity genes helped to isolate the effects of pregnancy weight gain, they said.
Lead researcher Dr David Ludwig, director of the New Balance Foundation Obesity Prevention Centre at Boston Children’s Hospital, said: “From the public health perspective, excessive weight gain during pregnancy may have a potentially significant influence on propagation of the obesity epidemic.
“Pregnancy presents an attractive target for obesity prevention programs because women tend to be particularly motivated to change behavior during this time.”
Writing in the online journal Public Library of Science Medicine, the authors conclude that high pregnancy weight gain increases a child’s risk of obesity by 8 per cent.
BMI measurements are obtained by dividing weight in kilogram by height in meters squared. A BMI of 18.5 to 24.9 is considered normal, 25 to 29.9 overweight and 30 and above obese.
They authors noted: “The 0.43 kg/m2 increase in BMI could represent a significant component of the estimated 2 kg/m2 increase in mean childhood BMI in the US since the 1970s