Omega-3 fatty acids during pregnancy
The body needs some fats to function normally. Fats are important sources of energy, and they help the body process certain vitamins, including vitamins A, D, E and K. U.S. dietary guidelines recommend that fats make up between 20 and 35 percent of an adult’s daily calories (1).
All adults, including pregnant women, should obtain their fat calories mainly from unsaturated fats. An unsaturated fat is one that is liquid at room temperature, like vegetable and fish oils. Omega-3 fatty acids are unsaturated fats.
Adults should limit their intake of saturated fats and trans-fats. Saturated fats are solid fats that are found in butter, meat and full-fat dairy products. Trans-fats are solid fats created from vegetable oils. They are found in pastries, cookies, chips and other processed foods. Saturated fats and trans-fats can contribute to heart disease and other health problems, while omega-3 fatty acids and some other unsaturated fats may help prevent them.
All fats, however, should be consumed in moderation because they contain more calories per gram than protein and carbohydrates. For example, carbohydrates and proteins have 4 calories per gram. Fats have 9 calories per gram.
What are omega-3 fatty acids?
Omega-3 fatty acids are a group of polyunsaturated fatty acids. The term polyunsaturated refers to a chemical structure that includes more than one double bond. The double bonds cause the fatty acids to melt easily, which is why they are liquid at room temperature. The numeral “3” refers to the position of the first double bond in the chemical structure.
There are three major omega-3 fatty acids:
- Alpha-linolenic acid (ALA)
- Eicosaentaenoic acid (EPA)
- Docosahexaenoic acid (DHA)
ALA is the parent omega-3 and cannot be produced by the body. It must be obtained through food. The body converts small amounts of ALA into EPA and then into DHA, but this process is not efficient. The best way to get enough EPA and DHA is to eat foods rich in these important nutrients.
What do omega-3s do in the body?
Omega-3 fatty acids help promote heart health by regulating blood clotting and heart rhythm and controlling inflammation. DHA is important during pregnancy because it supports the baby’s brain and eye development. During the third trimester, when rapid brain growth occurs, the baby requires 30 to 45 milligrams of DHA a day to support brain growth (2). DHA continues to support brain function throughout life, possibly helping to transmit nerve impulses from one brain cell to the next (3).
What foods contain omega-3 fatty acids?
Foods that are rich in ALA include (3):
- Canola oil
- Some leafy green vegetables, like spinach and salad greens
The main food sources of DHA and EPA are fatty fish (such as salmon, herring, sardines and fresh-water trout) and organ meats (such as calf’s liver). Omega-3s also are found in certain fortified foods (such as milk, juice, bread and yogurt) and in supplements containing fish oil or algae oil.
How much DHA does a pregnant woman need every day?
Experts recommend that pregnant and breastfeeding women consume at least 200 milligrams of DHA every day (2). Most pregnant and breastfeeding women in the United States consume only about 60 to 80 milligrams a day (4).
Women can get the recommended amount of DHA by eating two servings of fish, including fatty fish, per week (2). Fish are good sources of DHA because of what they eat in the wild. Farm-raised fish may not contain DHA unless they are fed foods rich in DHA.
Pregnant women should avoid fish that can be high in mercury, like shark, swordfish, king mackerel and tilefish (5). High levels of mercury can harm the baby’s developing central nervous system. Women can safely eat up to 12 ounces of fish that have small amounts of mercury (5). These fish include wild fish that are good sources of DHA (and EPA), including salmon, herring, sardines and fresh-water trout. Women also can get DHA from albacore (white) tuna, but should limit themselves to 6 ounces or less a week because albacore tuna can contain more mercury than canned light tuna (5).
Women who do not want to eat fish can look for other sources of DHA, such as fortified foods. They also can take a daily supplement that contains at least 200 milligrams of DHA. Several prenatal vitamins contain DHA, either from fish oil or other sources. A pregnant woman, however, should always check with her health care provider before taking any supplements.
How can taking DHA during pregnancy affect infant development?
Some studies suggest that babies of women with higher DHA consumption during pregnancy (from eating fish or taking supplements) may have better mental, visual, social and motor development than babies of women with lower DHA consumption (2).
- A Norwegian study found that 4-year-old children of women who received DHA supplements during pregnancy and lactation scored higher on tests of intelligence than babies of unsupplemented women (6).
- A study in Great Britain found that women who didn’t eat any fish during pregnancy were 48 percent more likely than women who ate at least 12 ounces of fish a week to have a child with low verbal IQ scores (7). However, it is unclear whether the benefits of eating more than 12 ounces of fish a week (which exceeds the current U.S. recommendations) outweighs the potential risks of higher levels of mercury exposure.
One recent study also found that children of women who took fish oil supplements during pregnancy were less likely to have developed asthma by age 16, possibly due to the effect of omega-3s on the immune system (8).
Do infants benefit from DHA after birth?
Rapid brain growth continues after birth. Breastfeeding women pass on DHA to their infants in breast milk. Breastfeeding women should consume at least 200 milligrams of DHA each day to support the baby’s brain growth (2).
Many infant formulas contain DHA and other omega-3s. Studies show that premature infants (those born before 37 completed weeks of pregnancy) benefit from the addition of omega-3s in formula with improvements in visual function and mental development (9, 10). The addition of omega-3s to formula also may benefit term infants. The American Dietetic Association recommends that full-term and premature infants who are not breastfed be fed a formula containing DHA and other omega-3s for at least the first year of life (10).
What are the health benefits of omega-3 fatty acids for adults?
Studies show that omega-3s, specifically DHA and EPA, help maintain heart health. DHA and EPA help reduce risk factors for heart disease. They lower the levels of risky fatty substances, such as LDL-cholesterol and triglycerides, in the blood and help prevent clogged arteries. Omega-3s also help regulate heart rhythm, reducing the risk of rhythm disturbances that can lead to sudden death and slightly lower blood pressure (3). The American Heart Association recommends that adults eat fish, particularly fatty fish, at least twice a week for its potential heart benefits (11).
DHA also is important to brain health throughout life. Researchers are looking into whether it could play a role in the prevention or treatment of Alzheimer’s disease and other forms of dementia (3).
Does the March of Dimes support grants on the effects of omega-3s on maternal and infant health?
The March of Dimes has supported research that suggests that maternal intake of fatty fish or omega-3 supplements may prolong pregnancy and help reduce the risk of premature delivery (12). A 2008 study supported in part by the March of Dimes reported that higher maternal fish intake during pregnancy and breastfeeding may improve attainment of developmental milestones at ages 6 and 18 months (13).
A current grantee is seeking to determine whether giving dietary supplements containing DHA during pregnancy and breastfeeding results in increased birthweights and improved scores on tests of infant development in developing countries. The study’s findings could lead to a cost-effective way to improve infant growth and development in countries where many children have poor growth in the early years of life. Another grantee is seeking to determine whether substituting omega-3s from fish oil for other fats usually used in intravenous feedings in infants with intestinal birth defects or intestinal complications from premature birth helps prevent liver disease, a common life-threatening complication in these babies.
- U.S. Departments of Health and Human Services and Agriculture. The Report of the Dietary Guidelines Advisory Committee on Dietary Guidelines for Americans, 2005.
- Koletzko, B., et al., for the Perinatal Lipid Intake Working Group. Consensus Statement: Dietary Fat Intakes for Pregnant and Lactating Women. British Journal of Nutrition, volume 98, 2007, pages 873-877.
- Office of Dietary Supplements, National Institutes of Health. Omega-3 Fatty Acids and Health. Last updated, 10/28/05, accessed 3/30/09.
- American Dietetic Association. DHA: A Good Fat. Nutrition Fact Sheet, accessed 3/30/09.
- U.S. Department of Health and Human Services and U.S. Environmental Protection Agency. What You Need to Know About Mercury in Fish and Shellfish. Accessed 4/2/09.
- Helland, I.B., et al. Maternal Supplementation with Very-Long-Chain n-3 Fatty Acids During Pregnancy and Lactation Augments Children’s IQ at 4 Years of Age. Pediatrics, volume 111, number 1, January 2003, pages e39-e44.
- Hibbeln, J.R., et al. Maternal Seafood Consumption in Pregnancy and Neurodevelopmental Outcomes in Childhood (ALSPAC Study): An Observational Cohort Study. The Lancet, volume 369, February 17, 2007, pages 578-585.
- Olsen, S.F. Fish Oil Intake Compared to Olive Oil Intake in Late Pregnancy and Asthma in the Offspring: 16 Years of Registry-Based Follow-Up from a Randomized Trial. American Journal of Clinical Nutrition, volume 88, 2008, pages 167-175.
- Makrides, M. Outcomes for Mothers and Their Babies: Do n-3 Long-Chain Polyunsaturated Fatty Acids and Seafoods Make a Difference? Journal of the American Dietetic Association, volume 108, number 10, October 2008, pages 1622-1626.
- American Dietetic Association. Position of the American Dietetic Association and Dietitians of Canada: Dietary Fatty Acids. Journal of the American Dietetic Association, volume 107, number 9, September 2007, pages 1599-1611.
- American Heart Association. Fish and Omega-3 Fatty Acids: AHA Recommendations. Accessed 3/30/09.
- Olsen, S.F., et al. Duration of Pregnancy in Relation to Seafood Intake During Early and Mid Pregnancy: Prospective Cohort. European Journal of Epidemiology, volume 21, 2006, pages 749-758.
- Oken, E., et al. Associations of Maternal Fish Intake During Pregnancy and Breastfeeding Duration with Attainment of Developmental Milestones in Early Childhood: A Study from the Danish National Birth Cohort. American Journal of Clinical Nutrition, volume 88, 2008, pages 789-796.
Funding for this article was provided in part by Martek. The March of Dimes does not endorse specific brands or products.