A new study suggests that pregnant women should continue to eat fish during pregnancy, with negative health effects of low-level exposure to mercury potentially outweighed by the beneficial effects of fish consumption.
Carried out by a team of researchers from Cincinnati Children's Hospital Medical Center and published online in the journal Neurotoxicology and Teratology, the study looked at the effect of the brain and nervous system on behavior – referred to as neurobehavior — of 344 5-week old infants, and a possible association with their exposure to mercury during pregnancy.
Neurobehavior was measured using a standard neurobehavioral scale, and mercury exposure using blood samples from the mother and umbilical cord blood samples from the child.
Researchers also gathered information from the mothers on how much fish they consumed during pregnancy, and estimated their polyunsaturated fatty acid intake — beneficial fats found in fish — based on type and amount of fish consumed.
From the data collected the researchers found that although 84 percent of mothers reported eating fish during pregnancy, in general participants had a low fish consumption and therefore low exposure to mercury, only consuming around two ounces of fish on average per week while pregnant.
However when looking at the children whose mothers had eaten more fish, therefore exposing children to a higher level of mercury, although these children did show unequal reflexes, they also showed better attention and needed less special handling than those exposed to lower levels of mercury.
Commenting on the findings, senior author Kim Yolton emphasized, "The better neurobehavioral performance observed in infants with higher mercury biomarkers should not be interpreted as a beneficial effect of mercury exposure, which is clearly neurotoxic. It likely reflects the benefits of polyunsaturated fatty acid intake that also comes from fish and has been shown to benefit attention, memory, and other areas of development in children."
Yolton concluded that, "The important thing for women to remember is that fish offers excellent nutritional qualities that can benefit a developing baby or young child. Moms just need to be thoughtful about which fish they eat or provide to their child."
Another recent study, published in January in Stem Cells, also found that eating fish whilst pregnant had beneficial health effects, providing expectant mothers with a rich source of omega-3 — balancing out the often over consumed omega-6 — which can have a positive effect on their child's development.
The latest advice from the US Food and Drug Administration (FDA) and Environmental Protection Agency (EPA) encourages pregnant women to consume eight to 12 ounces of low-mercury fish per week per week. They do however suggest avoiding fish with the highest mercury levels, including tilefish, shark, swordfish, and mackerel.