I'm taking Materna, and Omega 3-6-9 capsules WITHOUT mercury.
Fish oils are good for the development of the brain, heart, etc,. I used it later in pregnancy with DS and he's pretty darn smart.
If you decide to use fish oils, make sure you get a supplement without mercury or you may increase the risk of ASD.. I'd rather not get on the debate about Autism but many people believe mercury (from vaccines) are the main cause.. I personally feel its a combination of a lot of things. DS is at greater risk because his father had Asperger's (so I think its genetics).
Sorry rambling...