性器官-女性性器官
The Sex Organs - The Female Sex Organs

月经周期

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什么是月经周期？
妇女从青春期开始具有生殖能力，然后到了近50岁时会失去这种能力。然而，即使在她的生育年龄期，只有在每月一次两侧卵巢之一排卵的时候，她才能怀孕。这个按月循环的事件和其他有规律的身体变化一起，构成了女性的生殖周期。女性生殖周期最显而易见的外部征兆就是月经（按月流血）。因为这个原因，生殖周期也可以称为月经周期。当然，后一个术语好于前一个术语，因为包括不生育的几乎所有的妇女（包括不生育妇女）具体体验得到并且对它很熟悉。

第一次和最后一次月经
女孩的第一次月经（希腊：menarche，初潮）通常在11-13岁之间发生。无论如何，第二次月经可能远比刚刚来潮的初潮要好得多。在青春期，月经周期相当不规则。只有到了后来，相对准确的月经周期才能够建立。成年妇女的月经周期维持在28-35天之间。尽管如此，若干次不规则的月经周期总是有可能的和十分正常的。随着妇女渐渐衰老，不规则的月经周期又会出现。最后，到了绝经期，妇女的月经将完全停止

The Menstrual Cycle

What is the menstrual cycle?
A woman becomes capable of reproduction during puberty and then loses this capacity in her early fifties. However, even in her fertile years she can conceive only during a certain time once a month when one of her ovaries releases an egg. The monthly recurrence of this event, together with other regular body changes, constitute the female reproductive cycle. Its most obvious external sign is menstruation (monthly bleeding). For this reason, the reproductive cycle may also be called menstrual cycle. Indeed, this latter term has the advantage of referring to a concrete experience which is familiar to practically all women, including those who do not reproduce.

First and last menstruation
A girl's first menstruation (gr.: menarche) usually occurs between the ages of 11 and 13. However, the second menstruation may very well be much farther away than just another month. During adolescence, menstrual cycles are rather irregular. It is only later that some definite pattern is established. In a mature woman, menstrual cycles usually last between 28 and 35 days. Still, some irregularity is always possible and quite normal. The irregularity increases again as the woman grows older. Finally, after menopause, her menstruations cease altogether.