What are these taken for? Are you taking them?
DHA supplements are important during pregnancy (and after) because most of us don't get enough DHA in our regular diet. DHA is important in brain development of your fetus and can also be related to birth weight. You do not, however, just want to take any fish oil supplement when you're pregnant--there are no regulations regarding mercury in those particular supplements. So if you DO take a fish oil supplement, you want to make sure that it has been cleared of mercury and lead--I know there's a specific brand that is recommended, but I can't think of it off the top of my head. A DHA supplement is the way to go, which is derived from what fish actually eat--which is the original source of DHA anyway. You can buy the Expecta supplements at Target, or many prenatal vitamins already have it in them now.
ETA: Flaxseed meal and oil is another good non-fish source of DHA...I put ground flaxseed meal on my oatmeal in the morning, or even on salads sometimes.
There was a NYTimes article recently that discussed this. Aparently DHA might not be beneficial in pregnancy as previously thought.
I don't think it's a bad thing to take regardless. However, I am not supposed to take it during pg b/c of a blood clotting disorder.