In answer to the first part of your question, we do have CMV negative donors read to use for treatment at Manchester Fertility. CMV (cytomegalovirus) is a common virus which has no health risks to you but if you were to catch this during pregnancy does have some risk to the unborn child.  You are correct you could conceive naturally with a CMV positive man but when you are having treatment at a fertility clinic we try and reduce the risk to you and your potential child to an absolute minimum. Here we endeavour to match CMV status of the sperm donor and the recipient.