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Fish and Pregnancy: Health Benefits vs. Mercury Risks

Fish and Pregnancy: Health Benefits vs. Mercury Risks

Can consuming fish harm your fertility, pregnancy or baby? Many women are very concerned that fish is too contaminated to consume due to environmental pollution. Can these contaminants harm your chances of having a healthy pregnancy and baby? Is eating fish in pregnancy and during lactation safe? According to the Harvard School of Public Health (HSPH), the benefits of eating fish outweigh the health risks.

Fish is very nutritious, providing a lean source of protein, omega-3 essential fatty acids and a variety of vitamins and minerals to the diet. All of these play an important role in fertility, pregnancy and lactation. We urge couples to eat fish as part of a whole food nutrient dense natural fertility diet. The health benefits of consuming fish are an important part of pregnancy preparation!

In 2006 the HSPH examined a wide range of studies comparing health benefits of consuming fish weekly versus the major health risk of mercury, PCBs and dioxin contamination in adults, infants, and young children.

“Overall, for major health outcomes among adults, the benefits of eating fish greatly outweigh the risks,” said Dariush Mozaffarian, lead author of the study and an instructor in epidemiology at HSPH and in medicine at Brigham and Women’s Hospital. “Somehow this evidence has been lost on the public.”

The report by the HSPH, published in the Journal of the American Medical Association concluded that eating just 3 ounces of farmed salmon, or 6 ounces of mackerel a week reduced the risk of death from coronary heart disease by 36 percent and that the intake of fish or fish oil reduces total mortality, deaths from any causes, by 17 percent.

Fish Is Beneficial For Making a Baby


Fish supplies important omega-3 essential fatty acids to our diet. Omega-3 fats contain two acids that are crucial to good health: DHA (docosahexaenoic acid) and EPA (eicosapentaenoic acid). These two acids have been shown to be extremely healthy for the body. Low levels of DHA and EPA have been linked to depression and other mental health issues. DHA is essential for proper brain development, while EPA supports healthy behavior and mood.

  • These fatty acids aid in the production of hormones and reduce inflammation.
  • Omega-3s have a significant impact on the viability and health of sperm. When there are not enough fatty acids present, cholesterol replaces the needed fatty acids in the sperm membrane. This prevents sperm from proper maturation. This, in turn, helps create more free radicals, which damage any healthy sperm that may be present.
  • DHA is necessary in high concentrations for proper brain function, including proper development and cognitive function. DHA is an important component for a healthy central nervous system.
  • A 2003 study published in Pediatrics showed that mothers who took cod liver oil every day in pregnancy and 3 months postpartum while breastfeeding had more intelligent children than mothers who did not.
  • Supports proper formation of your baby’s nervous system, brain, eyes, and heart.
  • Having a sufficient level of DHA and EPA in your system is thought to help prevent miscarriage and premature delivery.
  • DHA and EPA together in pregnancy has been shown to lengthen gestation time.
  • Helps prevent postpartum depression.
  • Omega-3s are passed through breast milk to baby.


Fish is a great source of protein, essential for sustaining energy levels and a healthy pregnancy. Proteins are required for building and repair of our body tissue. This includes a growing baby in its mother’s womb.

Vitamins and Minerals

Fish is an excellent source of vitamin D, vitamin A, and B vitamins. It is also a rich source of zinc, potassium, calcium, iron, and magnesium.

Why You Should Avoid Certain Fish: Environmental Pollution

Certain fish should be avoided by women trying to become pregnant, are pregnant and/or breastfeeding a baby, but why? Environmental pollution is the number one reason why. The toxic culprits you should try to avoid are mercury, PCBs and dioxin.

The number one way that mercury makes its way into our freshwater systems and oceans is from emissions of coal-burning power plants and as waste water in chlorine production plants that use mercury to extract chlorine from salt.

  • Affects the development and function of the brain and nervous system.
  • Affects the development of the brain and nervous system in a developing fetus and young breastfed child.
  • Can be passed through the placenta and breast milk.

PCBs (Polychlorinated biphenyls)
PCBs are a broad family of human-made organic chemicals known as chlorinated hydrocarbons. They were manufactured in the United States from 1928 through 1979. Although they are no longer commercially produced in the U.S., they are still present in those products and materials that exist from that time. PCBs leach into our water systems, affecting the health of anything that lives in water.

  • Know to disrupt the hormonal system (endocrine disruptor).
  • Affects estrogen, androgens, and thyroid hormones.
  • Damaging to the liver, immune system, nervous system.
  • Linked to causing low birth weight and premature birth in humans.
  • Linked to a cause of cancer.

Dioxin is a group of highly toxic chemicals that are a byproduct of industrial processing using chlorine to manufacture herbicides and pesticides, and process pulp and bleach paper products (including the raw materials for feminine care products) as well as incinerate waste. Dioxin is considered a Persistent Organic Pollutant, POP for short, that slowly over time accumulates in our bodies. Dioxin leaches into water from a variety of sources.

  • Linked to causing cancer.
  • May alter gene expression by damaging DNA.
  • Shown to cause excessive endometrial growth and endometriosis.
  • Alters cell growth.
  • Alters metabolism.

Choose Fish Wisely!

Attribution: Bretwood Higman,

All of the above contaminants have been found present in many varieties of fish species and other foods we consume. The run-off from a variety of sources of human-made pollutants travel down our streams and into the ocean. As the contaminants travel up the food chain, toxin levels increase and are concentrated. Remember, we as humans are at the top of the food chain, which means by the time we consume meat, we are often eating the most concentrated amounts of environmental toxins accumulated by other animals. The FDA has established guidelines for eating fish for children, pregnant and lactating mothers, and women who wish to become pregnant. Fish are tested for mercury, PCBs and dioxin contamination. They are rated as low risk, high risk, and highest risk for mercury contamination.

Fish consumption guidelines are as follows:

  • 12 ounces of low risk fish may be consumed weekly
  • 3, 6-ounce servings of high risk fish may be consumed monthly
  • Avoid consuming fish in the highest risk category

Avoid large deep-water fish such as ahi tuna, swordfish, shark and Chilean sea bass due to their potential concentrations of mercury, and focus on fish such as wild Alaskan salmon, sardines, cod, and Alaskan halibut. Also, when choosing salmon, avoid north Atlantic farmed salmon and choose wild salmon instead. Farmed salmon contains antibiotics and toxic food dyes. Click here to see a full Consumer Guide to Mercury in Fish and Seafood to help you make healthy fish choices. I keep this guide with me in my purse so that when I go out to eat or I am at the grocery store I can make a healthy fish purchase.

Not only is extremely important to make smart choices in the fish we consume, but it is extremely important to make smart choices to live sustainably on this planet we call home. Environmental pollution is a major contributing factor to infertility problems, not just for humans, but for all living species worldwide. Be smart in how you live and what you choose to consume. Yes, reduce, reuse, and recycle… and avoid purchasing products that contain human-made toxic chemicals whenever possible! You will help save your fertility health and the fertility health of future generations!


Dr. Christine Traxler M.D., OB/GYN
Dr. Christine Traxler M.D., OB/GYN

Dr. Traxler is a University-trained obstetrician/gynecologist, working with patients in Minnesota for over 20 years. She is a professional medical writer; having authored multiple books on pregnancy and childbirth; textbooks and coursework for medical students and other healthcare providers; and has written over 1000 articles on medical, health, and wellness topics.  Dr. Traxler attended the University of Minnesota College of Biological Sciences and University of Minnesota Medical School,  earning a degree in biochemistry with summa cum laude honors in 1981,  and receiving her Medical Doctorate degree (MD) in 1986.

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    I was told that for infertility, a woman should take 2,000 mg of Omega 3’s daily. This seems high, and also I have a history of low blood platelets and Thallasemia Minor, also the high cost of this fish oil product. How much mg of Omega 3 a day do you recommend for infertility? Thanks, Kathryn

    • Dear Kathryn,

      The amount of omega 3s varies from supplement to supplement – given that infertility is such a broad topic and each fertility health issue has a variety of causes, we are unaware that there is a general standard recommended dietary allowance (RDA) of omega 3s, including EPA and DHA, for infertility.

      It is going to be best to follow the guidance of your healthcare provider.

      If interested in learning more about how omegas benefit fertility, the article Omega-3, Essential Supplement for Fertility and Pregnancy may be helpful. Besides a healthy Fertility Diet which includes fish and organ meats, we feel there is no better way to provide the body with healthy DHA and EPA, plus naturally occurring vitamin A and D3, than with a high quality cod liver oil supplement.

      Best wishes!