The following is from an article in progress. It pretty much covers all the antifungals. Ketoconazole is associated animal teratogenicity and should not be used in first trimester, but there is some work on use of ketoconazole for treatment of hypercortisolism of Cushing's if the fetus is a female in the 3d trimester. Fluconazole has been asociated with human malformation. Itraconazole is the least likely to harm since it has no effect on steroid hormones, but still should not be used.
All manufacturers advise against use during lactation.
Nystatin is OK in pregnancy and lactation. Check with your OBGs locally to see if they are less scared than we are. I have had two patients that inadvertantly taken ketoconizole during pregnancy over the past ten years. On each occaision the manufaqcturer sent me a comprehensive list of their experience with pregnancy and ketoconizole. My two patients did well with normal unaffected children.