While books often portray the menstrual cycle as a perfect 28 days, in real life there is much variation, both from woman to woman and for the individual woman over her life span. Medically, normal cycle length (the time between the first day of bleeding in one cycle and the first day of bleeding in the next) is anywhere from 21 to 35 days. In the first one to two years of menstruation it is quite frequent for menses to be irregular. After that time a woman, and especially one who is keeping track of her onot perishah (times of separation) knows approximately when to expect her period. Uterine bleeding outside the normal cycle times for most women, or markedly different from the usual pattern of a particular woman, is known as menstrual irregularity.
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All health and health-related information contained within Nishmat's Women's Health & Halacha Web site is intended to be general in nature and should not be used as a substitute for consulting with your health care professional. The advice is intended to offer a basis for individuals to discuss their medical condition with their health care provider but not individual advice. Although every effort is made to ensure that the material within Nishmat's Women's Health & Halacha Web site is accurate and timely, it is provided for the convenience of the Web site user but should not be considered official. Advice for actual medical practice should be obtained from a licensed health care professional.