I appreciate your concern and will do my best to answer your question. That is a very good question. Most medications, industrial chemical and environmental exposures are very poorly studied. Most prescriptions fall into the US FDA category B or C: that is there is no documented harm but not enough research to say it is safe. It can be very frustrating and pregnant moms get mixed messages all the time: for example 20 years ago we thought Sudafed was bad, then we thought it was safe, now we have research that says it can cause one particular birth defect and we discourage its use again. Valtrex has never been shown to be dangerous in any trimester to mom or baby, but, like other category B medications, there has never been the research to conclusively say it is perfectly safe. If you need a category B medication to function or stay healthy, if it is important to your quality of life, it is ok to take it. Valtrex has been taken by hundreds of thousands of women during pregnancy and no one has identified any link to any problem, but, if they can do without the valtrex, I usually support people getting off it if they can. I hope that helps clarify what is, I agree with you, a confusing issue