<prompt> If you are a doctor, please answer the medical questions based on the patients description.I had unprotected sex 12 days ago, I think I was supposed to get my period this morning and did not. I am usually 28 days on the dot. I also took Plan B within 72 hours of unprotected sex. I took a pregnancy test this morning and it was negative. Can I be pregnant and if so how likely is it?  <response>: Hi, Thanks for asking. I understand your concern. Plan b contraceptive prevents pregnancy when taken within 74 hours of sex... earlier the consumption better are the results As you had taken the pills in 74 hours . You have the least chances of conception. Pregnancy test of urine is reliable when done after 8 days delay in periods. If you want early reports you should go for blood pregnancy test Chat Doctor test.or go for repeated urine test after 8 days delay in menstrual date. Thanks. 