N.G.
It doesn't make a difference. Lots of the vitamin/pharma companies have 'gimmicks' to make theirs 'better' like the dha which, admittedly, is good for baby, but they get plenty of that in their formula after they are born, and get just as much benefit from that, if not more. They just switch up the formulas because every pregnant woman tolerates them differently- for example, when I was pregnant, all of the prenatals had a funny smell to them that was so intolerable that I couldn't take them at all. If I smell them NOW, I can't smell a thing! But then, just to put them in my mouth made me gag. I took flintstones vitamins and the doctor said that was absolutely fine, and both of my daughters were close to nine pounds, and healthy as can be.
I say take whatever is cheaper. I also like to ask for samples- they are free, can't beat that.