Scientists from Spain, led by Jordi Julvez from the Centre for Research in Environmental Epidemiology, found that increased fish consumption during pregnancy improves the baby's brain health and the effect can be observed in the child in later years.
In the U.S., the Food and Drug Administration advises pregnant women to eat up to 12 ounces, or about 340 grams, of fish every week. This recommendation was issued to encourage women to eat more fsh because it has "important nutrients for developing fetuses, infants who are breastfed, and young children," the FDA advice said. At the same time, the limit was specified to avoid an overconsumption of mercury, which can be found in most fish.
In the present study, the researchers analyzed data from 1,892 pregnant women who participated in a larger study called the Spanish Childhood and Environment Project conducted from 2004 to 2008. They specifically looked at the women's consumption of large fatty fish, small fatty fish and lean fish. The women ate an average of 500 grams of fish every week. Their vitamin D and iodine levels were obtained, and their cord blood tested for the presence of mercury. Additionally, their children were tested at 14 months and 5 years of age to evaluate their neuropsychological development.
The researchers found that the children's test scores improved for every 10 grams of fish added to the average 500 grams the women ate per week. However, this benefit was seen only up to 600 grams of fish consumption; no further benefit was observed for mothers' fish consumption beyond 600 grams.
Interestingly, the more fish the women ate, the more the children's autism-spectrum traits were reduced. Additionally, women who ate an average of 600 grams of fish per week did not show any sign of negative effects from mercury.
These results were observed particularly for pregnant women who ate more lean fish and large fatty fish in their first trimester.
"I think that in general people should follow the current recommendations," Julvez told Reuters. "Nevertheless this study pointed out that maybe some of them, particularly the American ones, should be less stringent."
These results are in line with data from another study showing that an excess consumption of omega-6 fatty acids (from nuts, eggs and vegetable oils) and an insufficient intake of omega-3 fatty acids (from fish) leads to abnormal brain development.
"Consumption of large fatty fish during pregnancy presents moderate child neuropsychological benefits, including improvements in cognitive functioning and some protection from autism-spectrum traits," the researchers concluded.
The study was published online Jan. 5 in the American Journal of Epidemiology.