If I have been taking the contraceptive pill for a few years and for the past few months my period has been arriving on Thursdays instead of Wednesdays.

It is common for menstrual cycles to vary slightly, even when taking birth control pills. If your period is more than 3-4 days late and you are usually very regular, it may be a good idea to take a pregnancy test. Changes in physical activity, stress, and other factors can also affect the timing of your period. It's generally not a cause for concern if your period is occasionally late or skipped.