i had unprotected intercourse wid my partner on da 1st day of my periods i.e on 18th dec. my periods were due on 18th of dis month as i have a 30 day cycle. but now my periods have been delayed by 5 days. wat can be da possible reason. is there any chance dat i am pregnant? i had taken a home pregnancy test on 1st jan and it had come negative. plz help!