Stress: Mental stress due to worry or too much on ones plate or quality of ones life if poor.If you simply worried that you could become pregnant from kissing, then that worry is enough to delay a period.
Physical changes: Only ones i know of that stop a period or make them a lot fewer is if a girl becomes very athletic and competitive in sports where she is in training all the time and has built up muscles. Lots of female athletes do not have a period, and some still do. Depends on how much of the physical stress is going on.
Lastly, females with cycles who spend the most time together whether friends at school, co workers or family members like Mom and sis, will find a strange thing of science happens to them. All the females period slowly change their time to coming earlier or later so that eventually all the women are getting their period at the same time. I can't say why this is but it is so. I have worked with females who asked if one of us had a pad or tampon cus theirs started at work and one by one, each of us admitted to having our period at the same time. People just don't tend to talk of awkward things like this but it is entirely a natural thing.
Well, there is one more reason for not having a period, and that would be if one was pregnant. [ Dragonflymagic's advice column | Ask Dragonflymagic A Question ]
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