Hi there! Oh congrats! Feels so good to take thee steps, doesn't it? !! Have you been trying a long time? Letrozole reduces estrogen to stimulate ovulation I believe. It stimulates the ovaries. So, side effects for this might include hot flashes, headaches and breast tenderness (kind of like menopause symptoms). Irritability and some anxiety may also be present. Good times, right? But worth it overall. Ovidrel is the trigger shot. It triggers the release of the egg. They probably told you to watch out for hyperstimulation of the ovaries and blood clots. Anyway, I hope it all works out for you sweetie!