Wiktionary
n. The recurring cycle of physiological changes in the females of some animal species that is associated with reproductive fertility; especially the cycle in a human woman.
WordNet
n. a recurring cycle (beginning at menarche and ending at menopause) in which the endometrial lining of the uterus prepares for pregnancy; if pregnancy does not occur the lining is shed at menstruation; "the average menstrual cycle is 28 days"
Wikipedia
The menstrual cycle is the regular natural change that occurs in the female reproductive system like the uterus and ovaries that make pregnancy possible. The cycle is required for the production of ovocytes, and for the preparation of the uterus for pregnancy. Up to 80% of women report having some symptoms during the one to two weeks prior to menstruation. Common symptoms include acne, tender breasts, bloating, feeling tired, irritability and mood changes. These symptoms interfere with normal life and therefore qualify as premenstrual syndrome in 20 to 30% of women. In 3 to 8%, they are severe.
The first period usually begins between twelve and fifteen years of age, a point in time known as menarche. They may occasionally start as early as eight, and this onset may still be normal. The average age of the first period is generally later in the developing world and earlier in developed world. The typical length of time between the first day of one period and the first day of the next is 21 to 45 days in young women and 21 to 35 days in adults (an average of 28 days). Menstruation stops occurring after menopause which usually occurs between 45 and 55 years of age. Bleeding usually lasts around 2 to 7 days.
The menstrual cycle is governed by hormonal changes. These changes can be altered by using hormonal birth control to prevent pregnancy. Each cycle can be divided into three phases based on events in the ovary (ovarian cycle) or in the uterus (uterine cycle). The ovarian cycle consists of the follicular phase, ovulation, and luteal phase whereas the uterine cycle is divided into menstruation, proliferative phase, and secretory phase.
Stimulated by gradually increasing amounts of estrogen in the follicular phase, discharges of blood (menses) flow stop, and the lining of the uterus thickens. Follicles in the ovary begin developing under the influence of a complex interplay of hormones, and after several days one or occasionally two become dominant (non-dominant follicles shrink and die). Approximately mid-cycle, 24–36 hours after the luteinizing hormone (LH) surges, the dominant follicle releases an ovocyte, in an event called ovulation. After ovulation, the ovocyte only lives for 24 hours or less without fertilization while the remains of the dominant follicle in the ovary become a corpus luteum; this body has a primary function of producing large amounts of progesterone. Under the influence of progesterone, the uterine lining changes to prepare for potential implantation of an embryo to establish a pregnancy. If implantation does not occur within approximately two weeks, the corpus luteum will involute, causing a sharp drop in levels of both progesterone and estrogen. The hormone drop causes the uterus to shed its lining in a process termed menstruation. Menstruation also occurs in some other animals including shrews, bats, and other primates such as apes and monkeys.
Usage examples of "menstrual cycle".
One or more eggs are lost by ovulation at each menstrual cycle, and far more eggs simply die (termed atresia).
You may find your menstrual cycle moves slowly to synchronise with the Moon.
She tried to think why she had been going to make him wait another couple of weeks, at least, maybe even a whole menstrual cycle.
Both medical and psychological writers on the subject are in agreement that Carrie White's exceptionally late and traumatic commencement of the menstrual cycle might well have provided the trigger for her latent talent.
All this is a long way from lance-constable Angua, even a long way from the female menstrual cycle.
One young woman wrote a good deal about the moon and her menstrual cycle.
The way of this is prepared by hormones present during the menstrual cycle.
I'm sorry, but my business cannot always be ruled by the whim of the doctors at the Women's Clinic or the vagaries of your menstrual cycle.