CRETE, Greece, Feb. 16 (UPI) -- While it is healthy for pregnant women to eat fish during pregnancy, a long-term study suggests eating too much fish may increase the chance for children to be overweight or obese.
A 15-year study in European countries and the United States showed children of women who ate more than three servings of fish per week grew faster and were more likely to be overweight or obese by age 4 or 6.
In a 2014 update to its recommendations, the U.S. Food and Drug Administration maintained that pregnant women should have two to three servings, or between eight and 12 ounces, of fish per week, but that they should be eating varieties of fish known to be lower in mercury while avoiding some altogether.
The recommendation is based on studies that show omega-3 fatty acids are important to fetal brain development, though mercury and other environmental pollutants found in some fish can have negative effects on developmental processes during pregnancy.
"Childhood overweight and obesity is considered a major public health issue," researchers wrote in the study, published in JAMA Pediatrics. "Rapid weight gain in infancy has consistently been associated with a subsequent elevated risk of obesity in childhood and later in adulthood."
Researchers at the University of Crete reviewed studies conducted in Belgium, France, Greece, Ireland, Italy, the Netherlands, Norway, Poland, Portugal, Spain, and Massachusetts with 26,184 pregnant women and their children, following up with them at 2-year intervals until the children were 6 years old.
Median fish intake among the women ranged from 0.5 times per week in Belgium to 4.45 times per week in Spain. Globally, women who ate fish more than three times per week gave birth to children with a higher BMI from birth to age 6 than those who ate three or less servings per week.
At age 4, children of women who ate more than three servings of fish were 14 percent more likely to be overweight or obese than those whose mothers ate less, with the likelihood increasing to 22 percent by age 6. The children of women who ate more than three servings per week were 22 percent more likely to grow faster than those whose mothers ate less.
The effects were also shown to be stronger in girls than in boys.
The researchers write that future research in healthy populations should consider specific compounds or pollutants in fish causing the higher incidence of obesity and interventions that target fish intake or supplement use.