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Fish and Seafood During Pregnancy
Reviewed By Medical Advisory Board

Sushi

Certain types of cooked sushi such as eel and California rolls are safe to eat when pregnant.

The FDA reports the greatest risk of seafood-borne illnesses is from raw or undercooked shellfish, particularly clams, oysters and mussels from contaminated waters. Bacteria such as Salmonella, Staphylococcus aureus, and viral infections (including hepatitis A) have all been found in raw seafood.

 

However, raw fish should also be avoided during pregnancy because it may contain parasites such as flukes or worms. Cooking and freezing are the most effective methods for killing the parasite larvae found in fish. The USFDA recommends cooking the fish to 140F. The fish should appear opaque and flaky when done. Freezing the fish at - 10F for at least 168 hours (7 days) will also kill most larvae [6]

Mercury in Fish and Seafood

Fish and seafood can be an important part of a balanced diet for pregnant women and those of childbearing age who may become pregnant. Indeed low consumption of fish was found to be a strong risk factor for preterm delivery and low birth weight in one study [7]. In addition maternal consumption of low levels of seafood may have a detrimental effect on child development [8]. Nonetheless, some large long-lived fish contain high levels of a form of mercury called methyl mercury that may potentially harm an unborn baby's developing nervous system.

Small fish absorb methylmercury from water as they feed on aquatic organisms. The longer the fish lives the more methylmercury the fish accumulates in its body. Large, long-lived, larger fish that feed on other fish (high in the food chain) accumulate the highest levels of methylmercury . In the United States the limit for methyl mercury in commercial marine and freshwater fish is 1.0 parts per million (ppm). In Canada the limit for total mercury content is 0.5 (ppm) [1,2]. Although the mercury levels found in most commonly consumed fish and seafood are well below these limits, the mercury levels found in several predator species frequently exceed 1.0 ppm
 

Food and Drug Administration (FDA) Recommendations

The FDA advises that pregnant women, women who may become pregnant, nursing mothers, and young children should avoid eating shark, swordfish, king mackerel and tilefish due to high levels of mercury in these fish [1] (Table 1).

The FDA also recommends that pregnant women can safely eat an average of 12 ounces of other types of COOKED fish each week You may eat up to 6 ounces (one average meal) of albacore tuna per week. Emphasis is placed on choosing a variety of  fish low in mercury such as shrimp, canned light tuna, salmon, pollock, and catfish. [1].So, when choosing your two meals of fish and shellfish, you may eat up to 6 ounces (one average meal) of albacore tuna per week.

If no local advisories about the safety of fish caught by family and friends are  available, eat up to 6 ounces (one average meal) per week of fish you catch from local waters, but don't consume any other fish during that week."[1]

Further State Recommendations
(in addition to FDA recommedations):

Washington State Department of Health [4]

Advises women of who are or may become pregnant, nursing mothers and young children to: 
Do not eat - shark, swordfish, tilefish, king mackerel, or tuna steaks.
For Healthy Fish Choices that are low in mercury and other contaminants and high in health benefits see the Healthy Fish Guide  http://www.doh.wa.gov/ehp/oehas/fish/fishchart.htm

Wisconsin Department of Natural Resources [5]

The Environmental Working Group lists other types of fish that may be contaminated by mercury, as well as by PCBs, include bluefish and striped bass, and freshwater fish (such as salmon, pike, trout, walleye) from contaminated lakes and rivers.
Their expanded list is available online: Brain Food: What Women Should Know About Mercury Contamination in Fish (PDF file)

 

Mercury Levels in Seafood Species[3]

The tables below show the average amount of mercury found in samples of fish and shellfish along with the lowest and highest amounts found in samples of each fish or shellfish

TABLE 1. Large Fish That Can Contain High Levels of Methylmercury[1,3]

SPECIES MEAN (PPM) RANGE (PPM)
Tilefish (Gulf of Mexico) 1.450 0.650 -3.730
Swordfish 0.995 ND - 3.220
Shark 0.979 ND - 4.540
King mackerel 0.73 0.230 - 1.670

PPM=parts per million
ND=Not detectable  - mercury concentration below detection level (Level of Detection (LOD)=0.01ppm)


TABLE 2. Fish or Shellfish That May at Times Contain High Levels of Mercury [3]
 
SPECIES MEAN (PPM) RANGE (PPM)
Orange Roughy 0.571 0.265 - 1.120
Marlin 0.485 0.100 - 0.920
Mackerel Spanish (Gulf of Mexico) 0.454 0.07 - 1.56
Grouper (All species) 0.448 0.006 - 1.205
Tuna all (Fresh or frozen) 0.391 0 - 1.816
Sablefish 0.361 0.090-1.052
Bass (Chilean) 0.354 ND - 2.180
Tuna (canned, Albacore) 0.350 ND - 0.853
Halibut 0.241 ND -1.520
Monkfish 0.181 0.106 - 0.289
Lobster Northern (Species unknown)       0.166

       ND - 0.451

Snapper 0.166 ND - 1.366
Bass
(Sea bass/ Striped Bass/ Rockfish)
0.152 ND - 0.960
Perch (freshwater) 0.150 ND - 0.325

PPM=parts per million
ND=Not detectable  - mercury concentration below detection level (Level of Detection (LOD)=0.01ppm)
 

TABLE 3. Fish and Shellfish With Much Lower Levels of Mercury [3]

In general, pregnant women  can eat up to 12 ounces per week of Fish and Seafood with Much Lower Levels of Mercury.

Pocket size this table
 
SPECIES MEAN (PPM) RANGE (PPM)
Tuna (canned. light) 0.128 ND - 0.889
Perch Ocean 0.121 ND - 0.578
Cod 0.111 ND - 0.989
Carp 0.110 ND - 0.271
Lobster Northern (American)    0.107 ND - 0.230
Herring 0.084 ND - 0.560
Trout Freshwater 0.071 ND - 0.678
Crab  (Blue, King, and Snow) 0.065 ND - 0.610
Haddock (Atlantic) 0.055 ND - 0.197
Crawfish 0.033 ND - 0.051
Pollock 0.031 ND - 0.780
Catfish 0.025 ND - 0.314
Squid 0.023 ND - 0.070
Salmon (Fresh or frozen) 0.022 ND - 0.190
Anchovies 0.017 ND - 0.049
Tilapia 0.013 ND - 0.084
Oysters 0.012 ND - 0.250
Clam 0.009 ND - 0.028
Shrimp 0.009 ND - 0.050
Salmon (Canned) 0.008 ND - 0.086
Scallop 0.003 ND - 0.033

PPM=parts per million
ND=Not detectable  - mercury concentration below detection level (Level of Detection (LOD)=0.01ppm)

REFERENCES
1. Center for Food Safety and Applied Nutrition, U.S. Food and Drug Administration An What You Need to Know About Mercury in Fish and Shellfish. 2004 EPA and FDA Advice For: Women Who Might Become Pregnant Women Who are Pregnant Nursing Mothers Young Children Accessed:8/23//06
2. Food Safety Facts on Mercury and Fish Consumption.
Canadian Food Inspection Agency  Accessed:10/4//02
3. Mercury Levels in Commercial Fish and Shellfish (1990-2010)
U.S. Food and Drug Administration Accessed:11/28//12
4. Fish Facts for Healthy Nutrition
Washington State Department of Health Accessed:3/12/10
5. Choose Wisely- a healthy guide for eating fish in Wisconsin, 2012(PDF file) Wisconsin Department of Natural Resources
Accessesed:11/28/12
6.USFDA. 8/21/1987. Food preparation - raw, marinated or partially cooked fishery products. In: "Retail Food Protection Program Information Manual", part 6, chapter 1, number 2-403. Center for Food Safety and Applied Nutrition, Retail Food Protection Branch.
7. Olsen SF and Secher NJ. Low consumption of seafood in early pregnancy as a risk factor for preterm delivery: prospective cohort study. BMJ. 2002 Feb 23;324(7335):447. PUBMED
8.Hibbeln JR. et al.,  Maternal seafood consumption in pregnancy and neurodevelopmental outcomes in childhood (ALSPAC study): an observational cohort study. 2007 17;369(9561):578-85. PUBMED


Update: 11/24/2012

Suggested Reading
Seafood WATCH
Fish4Health.net
 

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