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Fish consumption and docosahexaenoic acid (DHA) supplementation in pregnancy

Emily Oken, MD, MPH
Section Editor
Vincenzo Berghella, MD
Deputy Editor
Vanessa A Barss, MD, FACOG


Fish, including finfish and shellfish, is a healthful food that is low in saturated fat and high in protein. It is also the primary dietary source for two n-3 (also called omega-3) long-chain polyunsaturated fatty acids (n-3 PUFA): eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). EPA is a precursor of DHA and metabolized to DHA in the liver.

Maternal n-3 PUFA intake is necessary for optimal visual and cognitive development in offspring, and may also have other benefits when taken in pregnancy. However, fish consumption also exposes women to methylmercury and other environmental contaminants, toxins that cannot be completely avoided when fish are consumed. The beneficial effects of DHA and other nutrients in fish may outweigh the potential harmful effects of small amounts of methylmercury, especially when fish low in mercury and high in DHA are consumed [1,2].

DHA and EPA are also available as supplements and in fortified foods. These products are an alternative source of n-3 PUFA for women who cannot or choose not to consume fish, but may not have identical effects.

This topic will discuss potential obstetrical and fetal/infant benefits and risks of maternal consumption of fish and DHA supplements during pregnancy. Issues related to the health effects of fish and these supplements in the general population are reviewed separately (see "Fish oil and marine omega-3 fatty acids"). n-3 PUFA supplementation for breast- and formula-fed infants is also reviewed separately. (See "Long-chain polyunsaturated fatty acids (LCPUFA) for preterm and term infants".)


Potential neurodevelopmental effects — DHA is preferentially incorporated into the rapidly developing brain during the last trimester of pregnancy and the first two years of infancy, concentrating in brain gray-matter and retinal membranes [3,4]. Although infants can convert shorter-chain n-3 fatty acids to DHA to a greater extent than adults, it is not known whether such conversion is adequate for the developing brain in the absence of adequate maternal DHA intake [5-7].

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Literature review current through: Nov 2017. | This topic last updated: Jun 06, 2017.
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