A recently released scientific study of the eating trends of women of childbearing age indicates pregnant women are avoiding the types of seafood known to harbor the most mercury and are choosing instead to enjoy other, safer varieties. Over-exposure to mercury can cause devastating birth defects so public awareness campaigns have spread the message in many ways in recent years. This latest report indicates women are not only getting the message, but they are also heeding the warning.

The US Environmental Protection Agency (EPA) published the report using data collected by the National Health and Nutrition Examination Survey (NHANES). The EPA report focuses on all US women of childbearing age and their consumption of seafood specifically. The survey covered the years 1999 through 2010. The final report was published in July of 2013.

For the report, the general term “seafood” is defined as all salt- and freshwater finfish and shellfish normally consumed by humans. Blood samples from the women participating in the survey were analyzed for levels of mercury, which is found in trace amounts in most seafood but is concentrated at levels high enough to cause concern in some species, including king mackerel, shark, swordfish, and tilefish.

Pregnant women are at higher risk from mercury exposure in the seafood they eat because mercury can cause problems to the brain and nervous system of a developing fetus. Children exposed to excess levels of mercury in the womb are at increased risk of developing problems in these areas:

  • Attention
  • Cognitive thinking
  • Coordination
  • Fine motor skills
  • Hearing
  • Language and speech
  • Memory
  • Muscle strength
  • Peripheral vision
  • Sensation, especially around the mouth and in the hands and feet
  • Visual spatial skills

The EPA report indicates expectant moms in the US are continuing to enjoy seafood at rates that didn’t vary much over the years but they are making safer choices about the kinds of seafood they eat. Seafood is an important source for vitamins and minerals and many varieties are especially abundant in omega-3 fatty acids.

Blood levels of mercury in pregnant women are the best indicator of the trend away from mercury-rich seafood during pregnancy. Two important indicators of that trend are:

  • 34 percent drop in mercury in the blood at any level between 1999 and 2010
  • 65 percent drop in mercury at levels high enough to cause alarm

The rate of seafood consumption and blood levels of mercury in the general population of women of childbearing years (all women, pregnant or not) did not vary much, indicating women are still eating the seafood known to harbor high levels of mercury. The good news seems to be that, when pregnant, women are making safer choices about the seafood they continue to enjoy.

Source: “Trends in Blood Mercury Concentrations and Fish Consumption Among U.S. Women of Childbearing Age / NHANES, 1999-2010 / Final Report (.pdf).” EPA. US Environmental Protection Agency. Jul 2013. Web. Jan 16, 2014.