I am 19 weeks pregnant and have been taking the Boots Mum to Be vitamin supplement which contains fish oils since before conceiving. I have recently been reading about the levels of mercury and PCBs in fish (particularly farmed fish, salmon etc and tuna which I love although am trying to stick to the recommended weekly portions of these) and i am now starting to worry that what i thought were healthy supplements, must be tainted with pcbs and mercury. Anyone have any information on this?