Eating too much fish during pregnancy raises childhood obesity risk, study says

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Children whose mothers ate the most fish during pregnancy were up to 22 per cent more likely to be overweight or obese than were children born to women who ate the least, according to a new study. Photo: SCMP Pictures

Published: 8:35am, 16 Feb 2016Updated: 8:35am, 16 Feb 2016

Newborns whose mothers ate fish more than three times a week during pregnancy grew faster in their first two years of life and were more likely to be overweight or obese at 4 and 6 years old than were babies born to mothers who ate little to no fish during pregnancy, a new study says.

In a large study conducted across several countries, researchers found that the weight-related effects of a mother’s high fish consumption was more pronounced when the offspring was female.

Researchers suggested two explanations for their finding: that the Omega-3 fatty acids found plentifully in fish might predispose fetal stem cells to differentiate into fat cells, or that pollutants found in fish disrupt fetal hormones related to metabolism and prompt greater fat storage. But they acknowledged that the possibility that contaminants are to blame for the effect is “speculative,” since the study’s authors had no measure of the persistent organic pollutants in the fish the women ate.

In July 2014, the Food and Drug Administration and the Environmental Protection Agency recommended that pregnant women eat two to three servings (225-340 grams) of fish per week. The agencies’ advisory recommended that pregnant women steer clear of fish known to be contaminated with mercury and choose instead salmon, shrimp, pollock, light canned tuna, tilapia, catfish and cod.

The authors of the new study, published Monday in the journal JAMA Pediatrics, said their findings “are in line with” the EPA and FDA advisory.

The study tracked 26,184 pregnant women and their children, born between 1996 and 2011 in the United States and across Europe. They observed the growth patterns and weight status of the children up to the age of 6 years old. The pregnant women, who answered questionnaires about their food intake, reported they ate anywhere from less than half a serving of fish weekly (in the Netherlands, Belgium and Ireland) to as many as seven servings of fish per week (in Spain and Portugal).