I missed a pill (the 4th one in the first week to be exact), and I took it about 12 hours after I was meant to. Followed the instructions in the yasmin information sheet (just to take it when you remember, and continue taking the pills as normal). It said you don't need to use backup contraception unless you miss more than one pill. I had sex 4 days later but decided to take plan b just in case, what is the chance I could be pregnant? Too early to take a hpt.