Hi there, as mombojombo stated, you are very early in your pregnancy and many women still even drink before they find out they're pregnant at 4-5 weeks. It's uncommon for any negative side effects to occur to the fetus, but not unheard of. Definitely inform your OB about everything you ingested that could cause possible developmental harm so that the information can be documented and in the event that something occurs later in pregnancy, they can rule out anything they need to. I, personally, wouldn't worry too much about this, so as long as the medication wasn't used in an abusive way.
Hi, you are early in pregnancy hon. While I wouldn't take any more now that you know you are pregnant, I'm confident taking it for a day won't have caused harm. You can tell your doc at your first appointment but don't worry. Congratulations!!