A new study reveals that women who consumed fish 12 times per week and had higher mercury levels than women in the United States had no increase in autism symptoms in their children.
Previous studies have shown a possible link between mercury levels during pregnancy and an increased rate of autism. As a result, the Food and Drug Administration has made recommendations to limit the consumption of fish. A study released on July 23, 2013 investigated over a 30 year period autism symptoms in the children of women who had mercury levels six to eight times higher than women in the US and Europe. No link was found between the elevated mercury levels and autism in their children.
Mercury is released into the ocean from both volcanic eruptions and as fall-out from coal powered energy plants. The latter is a bigger problem in countries with looser emissions regulations. The mercury is absorbed by the fish, and is then passed on to the mother.
Fish contain nutrients that are extremely beneficial both for the expectant mother and the fetus. Omega-3 oils in fish are essential for proper brain development for the fetus. Fish oil supplementation may be helpful, but purity may vary from brand to brand, and it is generally accepted that obtaining omega oils from fish is the better choice. The new study results mean that the health benefits from eating fish will outweigh any potential harm.
Despite these new studies, the official recommendations from the FDA remain unchanged pending a full evaluation.
The March of Dimes has a list of other foods that should be avoided during pregnancy. These include consuming raw fish including uncooked shrimp and shellfish, products with uncooked eggs such as cookie dough, improperly cooked meats including deli meats, unpasteurized dairy products, and raw alfalfa sprouts. Coffee intake should be limited to 200 mg per day, which is roughly equivalent to a cup of espresso or a 12 ounce cup of coffee. Canned tuna is cooked during processing, so it is considered to be safe.
It is recommended that you discuss with your doctor these recent findings before changing your dietary habits.
 Edwin van Wijngaarden, Philip W. Davidson, Tristram H. Smith, Katie Evans, Kelley Yost, Tanzy Love, Sally W. Thurston, Gene E. Watson, Grazyna Zareba, Christine M. Burns, Conrad F. Shamlaye, Gary J. Myers. Autism Spectrum Disorder Phenotypes and Prenatal Exposure to Methylmercury. Epidemiology, 2013