MsG - hi there, (I'm no expert btw, but just have a keen interest in nutritional medicine) if you are a strict veggie and prefer not to take fish oils, then flaxseed is a good alternative. Again, Higher Nature do one here.
Although it's a good source of some omega-3 fatty acids, it doesn't contain the type of omega-3 fatty acid most often recommended for pregnant women (docosahexaenoic acid, or DHA), which the fish oil provides.
On Vitamin A, or specifically retinol which is the animal source, there's some interesting and confusing research out there.
Vitamin A has antioxidant and protective properties similar to those found in the mineral selenium, which can protect against cell mutation. It is essential for vision, building healthy cells in the gut and brain.
We're advised in this country to stay away from it, mainly because consuming it in extremely large doses can cause disability in the baby. But also deficiency during pregnancy can have devastating effects, and research has shown that for example, many autistic children are lacking in vitamin A.
Obviously this sort of info makes women swing from one extreme to the other, so personally I try to take a balanced view and include it from "safer" seeming sources.
From what I've read, the best sources of vitamin A are breast milk, organ meats, milk fat, and especially fish and cod liver oil, none of which are really prevalent in our diets. But also in eggs, butter and cheese which are obviously easier to include in a pregnancy diet.
The beta carotene version of Vitamin A (or bodies convert beta-carotene in to vitamin A, so again a good sourse if you want to stay away from retinol), is found in dark green leafy veg like spinach, and green and yellow fruits and veg like papaya, mango, pumkin, also carrots.
I'm in my third trimester and have stuck to what I did last time; eating a balanced diet, taking a good pre-natal vitamin (solgar) and a good omega 3 oil (higher nature).
I do know that cheaper and non-organic brand vitamins such as Pregnacare will use lower quality collating agents than more expensive brands like Solgar, which means the contents aren't as well absorbed in the body. Plus the better brands tend to use non-constipating forms of iron, rather than the cheaper iron sulphate you would get in Pregnacare etc. This is good for me as I suffer with getting bunged up in PG!
Hope I've not confused too much on the Vitamin A debate, but can definately say you get what you pay for as MrsMerryHenry said.