Gynecological conditions like polycystic ovarian syndrome (PCOS), and uterine cysts or polyps, can also bring about alteration in menstrual cycle. However, pregnancy
is still the most common cause of delayed
or missed period
So if there is a history of any unprotected intercourse then pregnancy should be ruled out.
It is very difficult to precisely confirm a diagnosis without examination and investigations and the answer is based on the medical information provided.