Maternal dietary intake of omega 3 fatty acids and birth defects

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-ABSTRACT It is well established that low levels of dietary folic acid are associated with an increased risk of neural tube defects. However, no other dietary nutrient has been clearly associated with birth defects. We propose to use the National Birth Defects Prevention Study (NBDPS) to assess the association between maternal diets low in omega 3 fatty acids and birth defects. The NBDPS, one of the largest population based studies of birth defects, interviewed 40,029 US mothers who delivered infants between 1997 and 2011. It includes 50 clinically well defined birth defect phenotypes. Dietary information was collected using a 58-item food frequency questionnaire developed by Willett and colleagues for The Nurses Health Study. In a preliminary analysis of NBDPS data for approximately 20,000 pregnancies, 31 percent of mothers reported eating little or no fish (a leading source of omega 3 fatty acids). This analysis examined 22 birth defects and observed that mothers who consumed as little as 1-3 servings of fish per month had a lower risk of having offspring with 5 of these birth defects. In addition, a small case control study found that mothers who consume diets high in fish have a reduced risk of heart defects. We are requesting support to undertake analyses of the final NBDPS database of 40,009 pregnancies. We will assess associations between three different levels of fish consumption (1-3 servings per month, 1 serving per week and 2 or more servings per week) and 50 different birth defect phenotypes. We will also assess associations between three other measures of maternal intake of omega 3 fatty acids and 50 birth defects, including two measures of plant sources of dietary omega 3 fatty acids. This project entails 1) coding of responses for up to 4,000 dietary supplements, 2) main analyses of 200 adjusted odds ratios and 95% confidence intervals, 3) testing multiple regression models to evaluate confounding and 4) analyses of sensitivity and bias. Including the 2 sensitivity analyses and the analyses of misclassification bias, we will calculate 650 adjusted odds ratios and 95% confidence intervals. The observation many women eat little or no fish, suggests that the percent of birth defects that may be explained by low fish consumption in the US could be relatively high compared to countries where fish consumption is higher. However, many women prefer not to eat fish because of concerns about the environmental contaminants that bio-accumulate in them. Hence it is important to not only understand the effect of fish consumption on birth defects but to also understand the effect of dietary intake of omega 3 fatty acids from plant sources on birth defects. We hypothesize that intake of plants rich in omega 3 fatty acids may also be protective against birth defects and could therefore serve as an alternative source of protective omega 3 fatty acids.