There is not much that interferes with a pregnancy test kit, so that's good news. Most prescription and OTC drugs do not affect test results, nor will birth control pills. However, some fertility drugs do contain hCG and can cause a false positive pregnancy test. Clomid, among the most popular ovulation-induction fertility medications, does not contain hCG, so no worries there. Tip: If you are taking fertility medications, ask your doctor if or how they will interfere with using a home pregnancy test (or an ovulation test, for that matter, as clomid can cause some problems with OPKs). Happy testing!