Hi, It is sometimes normal for periods to be late or delayed or missed. This can be as a result of one or more of the following reasons (listed below), and most times patient tend to have their periods return after a few weeks. i) Stress ii) New medication that can affect the hormones or lead to irregular periods like sertraline iii) Started or discontinued the pill, or the implant or the coil iv) Recent emergency contraceptive use v) Recent termination vi) Hormonal imbalance vii) Unprotected sexual intercourse, pregnancy viii) Sexually transmitted infection and so on. The above are the commonest reasons. Well done for taking the pregnancy test, I would suggest repeating this after 2 weeks and 4 weeks from missed period, if still not had your periods. Then arrange a review by your family physician if all the above are not the trigger for your missed period, and if you are still concerned about having a missed period. Take care. Hope I have answered your question. Let me know if I can assist you further. Regards, Dr. Joy Anosike, General & Family Physician