The normal menstrual cycle is the cyclical shedding of the endometrium, while menstruation is the vaginal cyclical bleeding experienced by women monthly as a result of the shedding of the endometrium. The endometrium is the inner lining of the uterus or womb. There in between 2 menstruation is the menstrual cycle.
In normal women the menstrual cycle is important to prepare the womb for union of the sperm and egg, implantation and nurturing the embryo. The first time a woman experiences her period is menarche while the time it stops in a women is menopause.
At menarche, the menstrual cycle may not be regular. However, as the woman gets older she will begin to have a regular menstrual cycle. The menstrual cycle occurs every 21 to 35 days, while your period (bleeding) lasts for about 2 to 7 days. Women who experience more than normal bleeding have menorrhagia (heavy menstrual bleeding). However, some women do not experience bleeding at all. This is amenorrhea.
Some factors that can cause irregular menstrual cycle are emotional anxiety from academic or pregnancy fears, major weight loss or weight gain, and chronic diseases in women.
During your menstruation, it is estimated that the amount of blood loss is usually less than about 80 mL. Bleeding for more than 7 days, soaking through pads/tampons quickly, or passing large clots repeatedly is suggestive of heavy menstrual bleeding. The amount of sanitary pad change in a day is often used by your doctor to estimate the amount of blood loss.
What causes menstruation in a woman?
Menstruation happens when pregnancy does not occur and estrogen and progesterone levels fall, so the uterine lining (endometrium) sheds.
The hormones and brain-ovary signals below work together to control the menstrual cycle.
- Decreased estrogen
- Decreased progesterone
- Hypothalamus
- Pituitary gland
- Luteinizing hormone (LH)
- Follicle stimulating hormone (FSH)
- Prostaglandins
- Gonadotropin releasing hormone (GnRH)
The hypothalamus produces GnRH hormone which stimulates the pituitary gland to produce LH and FSH. The FSH and LH hormone will then stimulate the ovaries to produce estrogen or progesterone. However, the level of estrogen and progesterone a control over the amount of FSH and LH that is produced by the pituitary.
What is menstrual cycle?
Prior to your period, you will experience some Premenstrual symptoms (PMS). These symptoms are headache, depression, abdominal bloating, abdominal cramps in women. The first day of your menstruation is the first day of your menstrual cycle. You will begin to shed the inner lining of the uterus.
At this point, the level of estrogen is low. This will stimulate the the pituitary gland to produce FSH and small amounts of LH. This FSH will stimulate the growth of the ovarian follicles. As the follicles grows they produce estrogen.
Within the follicles there are 2 types of cells. The theca and granulosa cells. Both cells are vital in the production of estrogen under hormonal influence of LH and FSH. The LH acts on the theca cells to produce androgens from cholesterol while the granulosa cells converts androgen to estrogen. Therefore, both LH and FSH are vital for adequate level of estrogen in an normal menstrual cycle.
The estrogen levels will continue to rise to a level when it will inhibit the production of FSH (negative feedback). This process will result in reduction of FSH production with resultant selection of one fast growing follicle. This is the dominant follicle. The other follicles regress and gets smaller. This happens around the first week of your menstrual cycle.
The growing follicle keeps producing estrogen, which helps build up the lining of your womb in response of ovulation that will soon occur. The rising estrogen will become rapid at about 36 to 48 hours before ovulation. This rapid increase will stimulate the pituitary to cause a surge in LH production and small FSH production. This is the LH surge.
Why is the LH surge important?
Ovulation usually occurs within about 12–36 hours after the LH surge. This is important in women who are planning to get pregnant. The ovulation kit women use is based on this principle. It detects the LH surge and tells the most fertile period in a woman.
Also, the LH with prostaglandins are important for ovulation. Through prostaglandins inflammatory like response there is expulsion of the egg due to smooth muscle contraction.
What happen next?
The ruptured follicle gets filed with blood and the theca and granulosa cells gets replaced with lipid filled cells called corpus luteum. The corpus luteum produces predominantly progesterone and small estrogen.
Therefore, before ovulation there is estrogen dominance while after ovulation there is progesterone dominance. Both hormones are important for preparing the endometrium for implantation.
If there is union of the sperm and egg, hCG level is raised and the corpus luteum will maintain pregnancy through production of its hormones.
If the sperm does not fertilize the ovum then there the corpus luteum will breakdown. Production of progesterone and estrogen is therefore reduced.
This reduction of these hormones will lead to breakdown and shedding of the endometrium. This will start another menstruation and menstrual cycle.
When is my ovulation period?
The lifespan of the sperm is about 5 days. However, the ovum lifespan of the egg is estimated to be 12 to 24 hours. In a woman with a 28 day cycle her ovulation period is on day 14 of the cycle. However, menstrual cycle is not regular for many women. And sometimes if regular, The menstrual cycle is either more or less than 28 days
Your first day of your last period (LMP) is used to calculate your ovulation period, but if your cycle is regular, you often ovulate about 14 days before your next period. To get pregnant, it is important to have regular sex at this period.
This complete guide to ovulation will help you
Ovulation Cycle, Test, Signs And Symptoms
The ovulation calculator can also be used to determine your fertile periods.
When is my menstrual cycle normal?
It is important for every woman to understand their menstrual cycle. These are features of a normal cycle.
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The duration of your period is between 2 to 7 days
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The frequency of period is about 21 to 35 days
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Small clots can happen, but very large clots or clots that keep coming (especially with flooding/soaking pads) can be a sign of heavy bleeding.
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The pain felt is not more than 48 hours after onset of your period and your normal activities are not affected
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There are no severe change in your mood and behavior.
When is my menstrual cycle abnormal?
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When your period suddenly becomes much shorter than your usual pattern
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Presence of large clots that keep coming
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When your period flow more than 7 days
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Bleeding in between periods or after sex
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Change in your mood that affects your activity.
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Presence of swelling in your abdomen (sometimes from fibroids) that can cause prolonged menstrual flow
If you experience any of this during your menstruation then inform your doctor, and do a pregnancy test if there is any chance you could be pregnant.
What are the causes of abnormal menstruation?
- Fibroids
- Endometriosis
- Adenomyosis
- Endometrial polyps
- Infection
- Polycystic ovaries (PCOS)
Now its your turn. Let us know if you experience a normal menstrual cycle or not. Share your experience below.
Dr Akatakpo Dunn is a Nigerian medical doctor, sonologist and Medical Director of Verah Clinic & Maternity in Warri, Nigeria. He holds an MBBS from the University of Nigeria, Nsukka, a Postgraduate Diploma in Diagnostic Ultrasound (India) and a Professional Diploma in Obstetrics & Gynaecology (RCPI). Through Medplux, he explains women’s health, pregnancy, fertility and ultrasound in clear, practical language so readers can make informed decisions with their own doctors.
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