<s>[INST] Hi doctor, We had sexual intercourse using a condom, but my fiance's period has been delayed by five days. We did a pregnancy test, which was negative. What is the reason for delayed periods? [/INST] Hi. How are you doing? Pregnancy need not be the only reason for no periods. If you have used proper protection and the urine test for pregnancy is negative, then you do not have to worry about pregnancy. Any young lady will take about 19 to 21 years of age to have a mature brain-ovary hormone axis, so till then, once in a while, you may miss your periods. Next month it will be fine. As you have ruled out pregnancy, I suggest taking any of the oral birth control pills, contraceptive pills, or 21 pills packet like tablet Novelon, Dear 21, Ovral G, Duoluton L, or Intimacy plus 3. Take one tablet twice a day for ten days and throw away the 21st pill, no matter what the cause is, she will get her periods within 7 to 10 days. Consult your specialist doctor, discuss with him or her and start taking the medicine after their consent. For more information consult an obstetrician and gynaecologist online --> </s>