When switching from a one combination birth control pill to a new combination birth control pill, is there a chance of getting pregnant the first week? I started the new birth control pill the Sunday of my old birth control pill's placebo week and I had unprotected sex with my boyfriend that Thursday. My doctor didn't tell me anything about the risk of pregnancy while switching pills so I assumed I should be fine. My mistake is that I should have clarified this with my doctor before having sex. I normally take my birth control pill around the same time everyday but sometimes I'm an hour or so, no more than 3 hours. I was on my old birth control pill for a year before switching. Should I be concerned about pregnancy?