In 2014, the Food and Drug Administration (FDA) and the Environmental Protection Agency (EPA) advised that pregnant women should eat 8 to 12 ounces of a variety of fish each week from choices that are lower in mercury, while also recommending the fishes to avoid such as shark, swordfish, king mackerel and tilefish due to high levels of mercury.
The nutritional value of fish is important during growth and development before birth, in early infancy for breastfed infants, and in childhood. Researchers also have it that eating fish during pregnancy can contribute to healthy brain development in the fetus by providing omega-3 oils.
However, results from the latest study yielded little evidence of harm in newborns whose mothers consumed low amounts of fish and who had low exposure to mercury. This is contained in a study led by Kim Yolton, PhD, from the Cincinnati Children's Hospital Medical Center in Ohio, published in the journal Neurotoxicology and Teratology.
The researchers measured gestational mercury exposure through maternal blood and infant umbilical cord blood. They also collected information on maternal fish intake and estimated consumption of polyunsaturated fatty acid based on type and amount of fish the pregnant women ate.
Although infants with higher prenatal mercury exposure showed asymmetric reflexes, after the researchers took fish consumption into account, they found that the infants whose mothers consumed more fish displayed better attention.
According to Yolton on their findings, 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. Also according to a research published online by JAMA Pediatrics, mothers who eat a lot of fish during pregnancy may be putting their child at risk of rapid growth and obesity.
It has been reported that babies exposed to mercury in the womb can have brain damage and hearing and vision problems.
According to the World Health Organization (WHO), mercury may have toxic effects on the nervous, digestive and immune systems, and also on the lungs, kidneys, skin and eyes.
According to the FDA, nearly all fish contain at least traces of mercury because as they feed, they absorb it. Mercury typically builds up more in certain types of fish, particularly in larger fish with longer life spans.