My husband and I would like to start trying for a baby soon, but I know that many of the skincare products I use have warnings that they may cause harm to a fetus. What I am most worried about is my Retin-A ointment and the 4% HQ product I use to help treat sun damage. I'll stop using both of these when we start trying to conceive, but should I stop using these even before that? How long do these typically "stay in your system"? Thanks!