Childhood obesity is linked to one of the healthiest foods pregnant women can eat

Take it easy on these.
Take it easy on these.
Image: AP Photo/Gemunu Amarasinghe
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The US Food and Drug Administration recommends that pregnant women eat two or three servings of fish per week, thanks to the animal’s high concentrations of protein, vitamins, and omega-3 fatty acids. Previous studies of women in Europe have found that moderate fish consumption leads to lower risk of pre-term birth and higher birth weights for babies.

But in this case, perhaps, more isn’t necessarily better. A sweeping new study has found that children of women who ate more than three servings of fish per week were more likely to be overweight or obese in childhood.

An international team of researchers looked at more than 26,000 pairs of mothers and children in Europe and the US state of Massachusetts over 15 years. Most mothers were nonsmoking women over 29 with normal body mass index (BMI) before pregnancy. The results were published this week in the Journal of the American Medical Association Pediatrics.

Fish consumption varied widely between individuals and countries, with women in Belgium eating just one-half serving of fish per week and women in Spain consuming an average of 4.45 servings. Women with high fish intake also tended to be older than other mothers in the study.

When researchers looked at their babies’ weight through childhood, they found that offspring of heavy fish eaters were just slightly heavier than their peers until age 2. At that point, while the BMIs of children exposed to low and moderate levels of fish in the womb dropped off as expected, those whose mothers ate lots of fish stayed consistently high through age six. The effect was greater in girls than in boys.

The team hypothesized that endocrine-disrupting chemicals found in fish as a result of environmental pollution could be one explanation, while cautioning that this was speculative. Certain pollutants carried in fish meat have been linked to weight gain in animals.

The findings don’t conflict with the most recent dietary guidelines drafted by the FDA in 2014. Expectant mothers have long been warned to stay away from certain types of fish, such as swordfish, known to contain high levels of mercury. The presence of other environmental contaminants just means that even when it comes to healthy eating in pregnancy, there can be too much of a good thing.