Worried About Period not Starting

Patient: I had to start my birth control pills a week late (3 weeks ago), and now it’s been 3 days after my normal period would start. I’m having all the symptoms including sore breasts and lower back pain, but no menstrual bleeding. I guess I should also add I had unprotected sex 2 weeks ago. Could my period be late because of the birth control or because there’s a chance I might be pregnant?

Symptoms: Lower back pain, sore breasts, no menstrual bleeding

Doctor: Hello,Ideally, birth control pills have to be started from day 2 of the cycle. So that it can achieve its effectivene ss by the time ovulation is due and can thus prevent ovulation. But as you have started a week late, then there may be chances of ovulation in this cycle if the birth control would have not reached adequate levels by 14-16 day of cycle. So if you have had unprotected intercourse 2 weeks ago and have missed period by 3 days , then it is better to rule out pregnancy with a urine pregnancy test on the 7 day post missed period.If the pregnancy is ruled out then the symptoms of sore breasts, low back ache mood swings can be attributed to premenstrual syndrome and your withdrawal bleed would start in few days on completing the pack or once you are on the sugar pills.I hope I have answered your query in detail, wishing you good health,regards,