Could you tell me what are some leads to of an irregular menstrual cycle?

Irregular period: An irregular periods is likely to be caused by hormones being off. This could be from stress, excess soy intake or a thyroid or prolactin issue, or gaining or losing weight. Less likely would be a pelvic infection or a polyp or fibroid in the uterus. If this is the first time and you have no pain then you can watch a month and see if it goes back to normal.