Clinical Update: Recommendations Regarding Fish Consumption in Pregnancy


We tell pregnant women to avoid aged cheeses and sushi.  Then we tell them, for fear of toxoplasmosis, that they cannot replace the kitty litter.  We tolerate neither alcohol nor smoking during pregnancy.  And, in light of a new study that links caffeine consumption with increased rates of miscarriage, we also have pregnant women panicked about imbibing anything stronger than chamomile tea.  Have we become too militaristic with the guidelines we enforce for our pregnant patients? 

Dr. Charles Lockwood at Yale New Haven Hospital addresses this question in his December editorial in Contemporary OB/Gyn entitled “Rising Mercury:  What to tell pregnant women about eating fish”.  He wonders if perhaps medical professionals have shortchanged the general reproductive populace by so severely restricting recommendations surrounding fish consumption in pregnancy. 

Since 1994, the US Food and Drug Administration and the Environmental Protection Agency have issued upper limits for the amount of fish which can safely be consumed by pregnant women, women who are breastfeeding, and children.  These limits were established in the wake of evidence that linked brain damage with the toxic levels of mercury contained in certain types of fish meat.  But what, Lockwood posits, of the potentially brain-boosting effects of the Omega 3 fatty acids so richly supplied by these fish sources?  It is possible that pregnant women who consume suboptimal amounts of these natural cognitive nutrients may actually slow the development of embryonic brains. 

As it stands, the FDA recommends a weekly allowance of up to 12 ounces of low-mercury fish, or about two fish meals a week.  High-mercury fish are to be avoided altogether.  King mackerel, shark, swordfish, tilefish, and some kinds of tuna are included in this off-limits category. 

The latest pro-con fish controversy followed the publication of the AVON Longitudinal Study of Parents and Children.  This study tracked 11, 875 pregnant women over the course of eight years.  As Lockwood writes, “There were essentially no differences between the offspring of low- and high-volume fish consumers.  However, when the offspring of no fish consumers and high fish consumers were compared, the former group had an increased risk of being at the bottom quartile of verbal IQ scores.”  Based on this information, “The Maternal Nutrition Group”, a consortium of doctors, nutritionists, and most notably, members of the seafood industry, stated that recommendations regarding fish intake in pregnancy should be set at a minimum of 12 ounces.  The group believes that the long-term, high-numbers AVON study painted the FDA’s rigid guidelines around mercury exposure in pregnancy as overblown hype.

So, where does this leave nurses who simply want to know what to tell their pregnant patient? Lockwood continues to abide by the FDA regulations.  He notes that aside from questionable special interests, the AVON study is confounded by other significant variables.  For example, pregnant women who consume greater quantities of healthy fish also tend to be more educated, live in higher quality housing, breastfeed, and abstain from smoking.  All of these IQ-enhancing factors could have potentially skewed AVON data.

When it comes to fish consumption in pregnancy, we as healthcare providers should stick to the party line.  Abiding by the FDA upper limits regarding the type and amount of fish to be consumed in pregnancy may be overly cautious, but for now, it’s the best advice we can give our patients.



Lockwood, CJ. (2007). Editorial: Rising Mercury:  What to tell pregnant women about eating fish. Contemporary OB/Gyn.      

Copyright 2008- American Society of Registered Nurses (ASRN.ORG)-All Rights Reserved


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