We've all heard that eating two to three servings of fish a week is good for pregnant women, thanks to their high concentration of omega-3 fatty acids and proteins. But, like many things, too much of a good thing can be bad for you. While previous studies have found that moderate amounts of fish consumption lowers the risk of pre-term birth and low birth weights, an expansive new international study published in the Journal of American Medical Association Pediatrics has found that pregnant women who ate more than three servings of fish a week, gave birth to babies who were more likely to struggle with childhood obesity.
Researchers looked at over 26,000 pairs of mothers and children in both Europe and the state of Massachusetts over the course of 15 years. And in case you were wondering, most of the moms were nonsmokers in good health with a normal body mass index over 29. After following the mother-child pairs, they discovered that children of the moms that ate more fish during pregnancy were just slightly heavier than their peers until about age two.
After age two, they found that the children of moms who were low to moderate fish eaters (1-3 servings a week) stayed about the same weight as their peers, while children of those who consumed significantly more fish (4 servings or more a week) had higher BMI values until about age six. It also seemed to impact girls more than boys.
This leads researchers to speculate that the change may be due to endocrine-disrupting chemicals that are often found in fish due to environmental pollutants.
According to study author Leda Chatzi, "It is possible that at higher levels of fish consumption, the potential adverse effects of contaminants mask or outweigh the benefits of omega-3 fatty acids." However, since they weren't able to distinguish the results by types of fish eaten or the water sources from where the fish came, the results remain "speculative."
Luckily for us, the findings are in line with the current U.S. Food and Drug Administration recommendation for pregnant women eat two to three servings of fish a week, but no more than that.