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Fish consumption and omega-3 long-chain polyunsaturated fatty acid supplementation during pregnancy

Emily Oken, MD, MPH
Section Editor
Susan M Ramin, MD
Deputy Editor
Vanessa A Barss, MD, FACOG


Fish, including finfish and other seafood, is a healthful food that is low in saturated fat and high in protein. It is the primary dietary source for two n-3 (also called omega-3) long chain polyunsaturated fatty acids (n-3 LCPUFA): docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), which are also available in fish oil supplements. DHA is of particular interest to obstetrical and pediatric providers because of its role in early brain development (see "n-3 long-chain polyunsaturated fatty acids (LCPUFA) for preterm and term infants", section on 'Metabolism and function'). Fish and fish oil consumption likely confers modest protection against preterm birth and, in turn, delivery of low birth weight newborns [1-4]. In addition, both DHA and EPA modulate several biologic pathways, and thus may reduce the risk of gestational diabetes, preeclampsia, and development of atopic disease in offspring [5]; however, these potential benefits remain unproven.

However, fish also may be contaminated by environmental pollutants, such as methylmercury, which have adverse fetal effects [6]. In the United States, any seafood consumption in the last 30 days is the most significant predictor of higher blood mercury concentrations in pregnant and nonpregnant women [7]. Because of the likely health benefits of fish, the US Food and Drug Administration (FDA) and the United States Environmental Protection Agency (EPA) have recommended that women of childbearing age, pregnant women, and breastfeeding mothers should consume 2 to 3 weekly servings of fish, but should preferentially choose fish lower in and should avoid all consumption of some types of fish that are higher in mercury (table 1) [8]. The United Kingdom has proposed similar guidelines [9,10].

This topic will discuss potential obstetrical and fetal/infant benefits and risks of maternal fish consumption during pregnancy. Issues related to the health effects of fish and fish oil consumption in the general population, as well as fish oil dosing and preparations, are reviewed separately. (See "Fish oil and marine omega-3 fatty acids".)

Dietary n-3 LCPUFA supplementation for breast- and formula-fed infants is also reviewed separately. (See "n-3 long-chain polyunsaturated fatty acids (LCPUFA) for preterm and term infants".)


Pregnant and breastfeeding women are encouraged to consume fish because it is a healthful food and a major source of docosahexaenoic acid (DHA), which is important for normal development of the retina and brain and, in turn, normal fetal and infant visual and cognitive function. DHA is preferentially incorporated into the rapidly developing brain during the third trimester of pregnancy and the first two years of infancy, concentrating in brain gray-matter and retinal membranes [11-13]. Fish is an excellent source of DHA, which is also available in fish oil supplements and fortified foods. Infants can convert the shorter-chain n-3 fatty acids found in nuts and seeds to DHA to a greater extent than adults, but it is not known whether such conversion is adequate for the developing brain in the absence of maternal DHA intake [14-16].


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Literature review current through: Feb 2017. | This topic last updated: Feb 22, 2017.
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