What about DHA supplementation?

Supplementation with n-3 fatty acids during pregnancy (particularly docosahexaenoic acid or DHA) has received considerable attention recently.

To date, there is no general consensus that maternal supplementation with n-6 and n-3 fatty acids has any beneficial effects to the infant. Various studies have shown an increase in gestation (about 4 days) for women who received supplemental n-3 fatty acids from fish oil, and an improvement in infant visual and cognitive development. Associations have also been identified between n-3 fatty acids, serotonin transporter genotype, and postpartum depression, indicating supplementation could decrease the risk of postpartum depression. (McMillen et al, 2008; Shapiro et al, 2012; Jensen 2006; Szajewska et al, 2006)

However, there is not enough evidence to determine thatn-3 fatty acid requirements are increased during pregnancy and an increase in n-3 fatty acid consumption may contribute to increased methylmercury intake. Thus, the recommended intake level for essential fatty acids is the same for pregnant women and non-pregnant women. In the US, essential fatty acid deficiency is very rare. (IOM, 2002)

DHA is primarily found in fish and other animal products. It can also be synthesized from alpha linolenic acid; flaxseed, canola, and soybean oils are high in alpha linolenic acid.