Why do some woman get their menstruation twice a month?

Answer:
Normal women will not have two full periods per month.

If a women is not on hormonal birth control, she may get her normal periods which are heavy and last serveral days, and about two weeks later may spot for a few days. This is called ovulation spotting, and can happen when the egg breaks through the corpus luteum cyst. This is considered normal.

If a woman is not on hormonal birth control, and is having what appears to be two heavy periods per month then she should definitely see a gynocologist as that is not normal

If a woman is ON hormal birth control and is having bleeding between periods, this is called breakthrough bleeding. Then her birth control method should be changed, either with the dosage or type.

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Most women's cycles are about 28 days long. Most months are longer than that. At some point every year, most women will have a month in which they start 2 periods.

If you're talking about something more than that, see your doctor.

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