Fish contains nutrients that are essential for pregnant women as they promote healthy fetal development. These vital nutrients include omega-3 fatty acids, protein, vitamins, and minerals such as iron.
But some fish can be dangerous to pregnant women as they contain high levels of mercury.
If you regularly eat fish high in mercury, the substance over time can accumulate in your bloodstream. Too much mercury in your bloodstream could damage your baby's developing brain and nervous system.
Mercury can be an odorless, invisible, poisonous vapor. It’s released when spilled or when something containing it breaks. It’s also released through industrial processes, like burning waste or coal in power plants.
Mercury released into the environment becomes a serious threat when it settles into oceans and waterways, cautioned the National Resources Defense Council. There, it builds up in the fish that we eat.
Once mercury enters a waterway, it is absorbed by a naturally occurring bacteria and converted to methylmercury.
Methylmercury is a neurotoxin found in most fish in at least small amounts. In high amounts, methylmercury can be toxic to the nervous system.
There are four types of fish that should be avoided by pregnant or breastfeeding women due to their high levels of mercury levels. These are king mackerel, shark, swordfish, and tilefish from the Gulf of Mexico.
These fish can have mercury concentrations that are 10,000 times higher than those of their surrounding habitat, reported NRDC.
Canned light tuna on average may appear safe but some testing has shown that mercury levels can vary from can to can, advised the Mayo Clinic.
People risk ingesting dangerous levels of mercury when they eat such contaminated fish. Since mercury is odorless, invisible and accumulates in the meat of the fish, it can't be avoided by trimming off the skin or other parts.
Babies exposed to mercury in the womb are at risk for brain damage, as well as hearing and vision problems.
During the first several years of life, children’s brains are still developing and rapidly absorbing nutrients. Even in low doses, mercury can affect their development, delay walking and talking, shorten attention span and cause learning disabilities.
Less frequent, high-dose prenatal and infant exposures to mercury can be much worse. These can cause blindness, cerebral palsy, deafness and mental retardation.
The bottom line? According to the Mayo Clinic, eating average amounts of seafood containing low levels of mercury during pregnancy hasn't been shown to cause problems.
As long as you avoid fish known to have high levels of mercury, fish can still be a regular part of a healthy-eating plan during pregnancy.
Sources:
"Mercury Levels in Fish - American Pregnancy Association." American Pregnancy Association. 30 Apr. 2012. Web. 10 Mar. 2015.
http://americanpregnancy.org/pregnancy-health/mercury-levels-in-fish
"NRDC: Mercury Contamination in Fish - Learn About Mercury and Its Effects." NRDC: Mercury Contamination in Fish - Learn About Mercury and Its Effects. Web. 10 Mar. 2015.
http://www.nrdc.org/health/effects/mercury/effects.asp
"Pregnancy Week by Week." Pregnancy and Fish: What's Safe to Eat? Web. 10 Mar. 2015.
http://www.mayoclinic.org/healthy-living/pregnancy-week-by-week/in-depth/pregnancy-and-fish/art-20044185
"Staying Safe." Mercury and Pregnancy. Web. 10 Mar. 2015.
http://www.marchofdimes.org/pregnancy/mercury.aspx#
Reviewed March 12, 2015
by Michele Blacksberg RN
Edited by Jody Smith