Evidence from Epidemiologic Studies
A cross-national comparison of infant birthweight for the period 1969–1981 found that Faroe islanders had the highest average birthweight (3610 g) among the 33 countries studied. Olsen and colleagues hypothesized that this difference (5–9% after standardization) might be attributable to the high fish consumption of the Faroe islanders. Additionally, an observational cohort study from Iceland noted that women who consumed cod liver oil in early pregnancy (~14% of the study population) gave birth to heavier babies than women who did not. However, other epidemiologic investigations in this area have yielded conflicting results. For example, a large Danish birth cohort study found increased risk for low birthweight (< 10th percentile for estimated gestational age) among infants born to women who consumed more than 60 g of fish per day. Further analysis found this risk to be confined to consumers of fatty fish and not lean fish. Likewise, in a small Massachussetts cohort, PUFA intake in the highest quartile was associated with a 94 g decrease in birthweight compared with the lowest quartile. These studies left unanswered the question of whether the observed decrease in growth is attributable to the omega-3 fatty acids or to industrial contaminants found in some fish and seafood.
Evidence from Clinical Trials
By contrast, randomized clinical trials of the use of omega-3 fatty acid dietary supplements during pregnancy have demonstrated no effect on birthweight. In Makrides' Cochrane review of marine oil supplementation during pregnancy, five trials, including 2302 women, were combined to assess the outcome of low birthweight (< 2500 g). No difference in low birthweights was noted nor was any difference in mean birthweight or small for gestational age found. Likewise, in two recently published systematic reviews of LC-PUFA supplementation among both high- and low-risk women, Horvath and Szajewska[46,47] found no harmful or beneficial effects on birthweight, low birthweight or recurrent intrauterine growth restriction.
Expert Rev of Obstet Gynecol. 2010;5(1):125-138. © 2010
Cite this: Role of Omega-3 Fatty Acids in Maternal, Fetal, Infant and Child Wellbeing - Medscape - Jan 01, 2010.