Well, according to First Response pregnancy tests….it can detect the pregnancy hormone up to 5 days before your missed period. BUT, I’m really starting to think that home prego tests don’t work, because my period was due a week and 3 days ago, I’ve taken 4 First Response tests, and all have been negative. My periods are NEVER this late. SO, you should try, and let me know the results so I can compare. Good luck