What foods should be avoided during pregnancy?

From the Guidelines

Pregnant women should avoid high-mercury fish, raw or undercooked meats, poultry, eggs, and seafood, as well as unpasteurized dairy products and juices to minimize the risk of foodborne illnesses and protect both maternal and fetal health. The American Heart Association recommends that pregnant women consume fish, especially oily fish, at least twice a week, but avoid fish with high levels of mercury, such as shark, swordfish, king mackerel, and tilefish 1. According to the guidelines, pregnant women can eat up to 12 ounces (2 average meals) per week of a variety of fish and shellfish that are lower in mercury, such as canned light tuna, salmon, pollock, and catfish.

Key foods to avoid during pregnancy include:

• High-mercury fish such as shark, swordfish, king mackerel, and tilefish
• Raw or undercooked meats, poultry, eggs, and seafood due to the risk of harmful bacteria like Salmonella and Listeria
• Unpasteurized dairy products and juices due to bacterial contamination risks
• Raw sprouts, unwashed produce, and deli meats or hot dogs (unless heated until steaming) due to listeriosis risks
• Excessive caffeine (limit to 200mg daily) and alcohol (completely avoid)

These restrictions help prevent foodborne illnesses that can cross the placenta and potentially harm the developing fetus, whose immune system isn't fully developed, as noted in various guidelines 1. Following these guidelines reduces the risk of complications like miscarriage, premature birth, and developmental issues.

From the Research

Foods to Avoid During Pregnancy

There are limited studies available that directly address foods to avoid during pregnancy. However, some studies provide information on the safety and efficacy of supplements and the potential risks associated with certain nutrients.

• The study 2 found that high seafood consumption was an independent risk factor for high maternal mercury levels, while vitamin supplementation was a protective factor.
• Another study 3 found that prenatal vitamins may contain toxic elements such as lead, inorganic arsenic, cadmium, aluminum, nickel, titanium, and thallium, which can be harmful to the mother and offspring.
• The study 4 recommends that prenatal supplements should contain a wide range of vitamins and minerals, but notes that very high or low levels of certain nutrients should be avoided.
• The study 5 suggests that optimal mineral supplementation can significantly reduce the risk of pregnancy complications and infant health problems, but notes that dietary intake of minerals is often below the Recommended Dietary Allowance (RDA) in the U.S.
• The study 6 discusses the roles of critical nutrients in pregnancy and the available evidence on the use of supplements to reduce risks and improve maternal and fetal outcomes, but does not specifically address foods to avoid during pregnancy.

Nutrients to Limit or Avoid

Based on the available studies, the following nutrients may be harmful to pregnant women in excessive amounts:

• Mercury, which can be found in high levels in seafood 2
• Lead, which can be found in prenatal vitamins 3
• Inorganic arsenic, which can be found in prenatal vitamins 3
• Cadmium, which can be found in prenatal vitamins 3
• Aluminum, nickel, titanium, and thallium, which can be found in prenatal vitamins 3