Family Planning Plus

You should be fine. Though we recommend taking your pill around the same time (within a three hour time period) every day, being only four hours late should not affect the pill’s ability to prevent pregnancy. Since you are on the pill now, your period doesn’t really have any effect on your fertility since you are no longer ovulating. However, missing pills does affect your fertility. Missing a pill by more than 24 hours may cause a drop in your hormone level which could allow you to ovulate.  

The pill works continually as long as you are taking a pill every day (even during your sugar or placebo pills. By taking hormone pills for three weeks straight, you build up enough hormones in your body to last you through your placebo pill week (the last week of pills) and you remain protected against pregnancy during that week. It is important, however, to remember to take the first hormone pill of your new pack the very next day after finishing the previous pack.