I found this... Flax is high in Essential Fatty Acids, which are important for infant development. This article discusses flax oil, but ground flax is also beneficial. The first link, and the info that I have printed come from a site selling flax oil, so I double checked their info against a non-biased site, and they seem to be right on.
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Mom, taking care of your baby during pregnancy and immediately following birth by ingesting an adequate amount of a special fats called omega-3 fatty acids will help your child grow up to be healthier adult. Conversely, without adequate amounts of this special fat, your baby may suffer virtually irreversible health problems during childhood and as an adult.
Low Levels of Special Fat During Pregnancy
Lead to Adult Blood Pressure Problems
In the March 2001 issue of Nature Medicine, researchers suggest for the first time that an essential nutrient, alpha-linolenic acid (ALA), when supplied in the early developmental period, can affect blood pressure later in life. A member of the omega-3 fatty acid family, ALA can be converted in the human body to other members of this family such as docosahexaenoic acid (DHA).
Meanwhile, additional research shows us that this same nutrient is essential to normal visual and neurological development and that it's deficit during pregnancy and in the first few months following birth can result in subtle behavioral disorders as well as possibly increased mortality during the perinatal period (from the 20th week of gestation through the 28th day of newborn life).
In the Nature Medicine study, the researchers found that the offspring of a specific breed of rat, with little predisposition for high blood pressure, suffered elevated blood pressure later in life if they experienced a deficiency of omega-3 fatty acids during the perinatal period. Their blood pressure remained elevated even when they were given the nutrient as adults.
In the experiment, which involved various dietary regimens, some animals were raised on a diet deficient in omega-3 fatty acids and others on a diet with an adequate supply of the fatty acids in the form of ALA in order to promote normal brain DHA levels. Later, some of the animals were switched to an ALA-rich diet, while others continued to be denied the important nutrient.
The researchers found that even as adults with equal brain levels of DHA, animals whose mothers were fed an ALA-rich diet during the earliest pregnancy stages of the study had the lowest levels of blood pressure. Animals given ALA later on as adults had intermediate high blood pressure, but animals deprived of ALA altogether had markedly higher levels.
The body uses ALA to manufacture DHA, which is found at high concentrations during the perinatal period in the brain and retina. The animals deprived of ALA and therefore DHA during pregnancy also tended to drink less water and consume more sodium, indicating an aberration in their cellular water/sodium sensors, which influence water-mineral balances and, consequently, blood pressure. These aberrations appear to be permanent, based on this preliminary research...
...Flaxseed is the richest source of omega-3 fatty acids.
We also urge women of childbearing age to supplement their diets with oceanic-derived omega-3 fatty acids. But, we urge women of childbearing age to avoid fish oil capsules and seafood that could be polluted with industrial chemicals or pesticides. Thus, women should avoid excess intake of tuna; although a rich source of omega-3 fatty acids, tuna tends to accumulate methylmercury, a potential fetal toxin. Swordfish tends to accumulate PCBs and methylmercury. And, with all due respect to Rudin and Felix, their recommendation for consuming bluefish is a poor one, since this species, found along the East Coast, is one of the most contaminated commercially available fishes. Best choices would be Pacific salmon (preferably wild harvested) once or twice a week, with tuna limited to once weekly.
In summary, be sure to consume one to three tablespoons daily of flaxseed oil and one to two servings of omega-3 fatty acid-rich seafood weekly or their equivalent in the form of a dietary supplement.
discontinue flax if pregnant? 
