My wife started taking Sprintec 3 weeks ago. She started her white pills today but as of yet she has not had a period. Is it common in Sprintec to miss your first period or start late or should I be heading to the store for a pregnancy test? thanks

P.S. If she is on her 4th week i.e. the placebo pills and has not had her period then can we have unprotected sex or are we rolling the dice here?