A period, or menstruation, is the shedding of the endometrium - the lining of the uterus (womb). Menstruation is also known as menses. Menses are part of normal sexual health for women during reproductive age.
Menstruation that includes bleeding from the vagina is found mainly among humans and similar animals, such as primates.
In humans, a period is a shedding of endometrial tissue from the womb that is released through the vagina.
Women have a period approximately every 28 days; however, there is some variation in this cycle, ranging from a 24-day to a 35-day cycle. A period is part of the woman's menstrual cycle.
Dr. Paula Hillard, professor of obstetrics & gynecology and pediatrics at the University of Cincinnati College of Medicine, said: "The menstrual cycle is a window into the general health and well-being of women and not just a reproductive event."
Contents of this article:
Fast facts on menstruation
Here are some key points about menstruation. More detail and supporting information is in the main article.
- Periods normally start between the ages of 8 and 16
- On average, around 5-12 teaspoons of blood are lost
- Symptoms of premenstrual syndrome (PMS) include bloating, irritability, and breast tenderness
When do periods start?
Menarche - the start of periods - will occur when all the parts that make up a girl's reproductive system are mature and working together.
A girl's periods generally begin between 8 to 16 years of age. On average, they start when a girl is about 12. Menstruation is a major stage in a girl's puberty. It is one of several physical signs that a girl is becoming a woman.
Approximately 6 months before getting her first period, a girl may detect more clear vaginal discharge. Unless the discharge has a strong odor or causes itchiness, this is normal and nothing to worry about. The periods will occur regularly until the woman reaches her menopause when the woman is aged about 45-55.
The menstrual cycle
Women have a period approximately every 28 days
Hormones are released by the pituitary gland in the brain to stimulate the ovaries during the reproductive cycle. These hormones cause some of the woman's eggs, which are stored in the follicles of her ovaries, to start to grow and mature.
The follicles start producing estrogen - a hormone. The increased estrogen causes the womb lining to become thicker in preparation for receiving a fertilized egg.
If a woman has had sex within several days of the egg being released and sperm is present in her fallopian tube, the egg may become fertilized (she becomes pregnant). However, it is important to note that pregnancy is possible with unprotected sex at any time during the menstrual cycle.
If the egg is not fertilized, estrogen and progesterone levels will drop, and the lining of the uterus (endometrium) will start breaking down - marking the start of the period.
The period consists of a small amount of blood and the endometrium. The bleeding is caused by the breaking of fine blood vessels within the womb as the lining detaches itself.
A period generally lasts about 5 days. Bleeding tends to be heavier during the first 2 days.
Symptoms of a period
During a woman's period, her blood flow may appear heavy. However, in the majority of cases, the amount of blood lost is around 5-12 teaspoons.
Premenstrual syndrome (PMS)
Symptoms of PMS may include abdominal cramps and bloating
PMS (also called premenstrual tension, PMT) is a collection of emotional, psychological, and physical symptoms that are linked to a woman's menstrual cycle.
The following symptoms may be felt by some women in the days leading up to her period - symptoms of premenstrual syndrome:
- Abdominal bloating
- Headache (including migraine)
- Pains, especially backache
- Feeling generally emotional or troubled
- Lack of concentration
- Breast tenderness or swelling
- Slight weight gain
- Binge eating
As soon as the period begins (the woman starts shedding blood), the symptoms generally improve. In the majority of cases, symptoms will be completely gone by the time the period has ended.
The following factors may increase the chances of PMS:
- High caffeine consumption
- A history of depression or other mental illness
- Smoking and alcohol consumption
- A family history of PMS
- Low levels of some vitamins and minerals, calcium, and B vitamins
What are irregular periods?
If a female has irregular periods, it means that there are variations in the interval length between periods. The amount of blood lost, as well as the duration of bleeding, may also vary. Irregular periods can have several different causes, and treatment will depend on the cause.
The majority of irregular periods are benign (harmless). However, there are other causes of irregular periods, which can be discussed with a doctor.
Shifts in period regularity are more common in the perimenopause (when a woman's body begins its transition into menopause).
Many women have missed a period at some time. This could be for no apparent reason, or in anticipation of a pregnancy, or perhaps because of anxiety or tension.
Irregular periods may be caused by the following factors (this list is by no means exhaustive):
- Benign lesions like uterine fibroids, endometrial polyps, and scarring
- Hormone imbalance
- Bleeding disorders
- Medications (including birth control medications like IUDs)
- Infection in the uterus
- Cancer of the uterine lining or cervical cancer
What is amenorrhea (absent periods)?
Amenorrhea is when a woman stops having periods altogether. There can be many reasons for this, including excessive exercise, stress, excessive weight loss, some medications, and hormonal problems, such as PCOS (polycystic ovarian syndrome).
Doctors may prescribe hormonal therapy as a treatment for amenorrhea.
Period pains (dysmenorrhea)
This is a medical condition which includes severe uterine pain during menstruation. The majority of women experience minor pain during menstruation. When the pain is so severe that it interferes with normal activity, it is called dysmenorrhea and may require medication.
Some women experience pain during the days before a period, while others have dysmenorrhea during the period. As menstruation tapers off, the pain generally does, too. Some women experience both dysmenorrhea and menorrhagia (excessive blood loss).
The following symptoms may be experienced by women with dysmenorrhea:
- Cramping in the lower abdomen
- Low back pain
- Pain in the lower abdomen
- Pain which radiates down the legs
- Tiredness (fatigue)
The following women are at higher risk of experiencing dysmenorrhea:
- Over 30 years' old
- Individuals with a BMI over 20
- Those whose periods started before they were 12
Treatments for period problems
- Painkillers - for period pains and discomfort, many women find painkillers are effective. This could include paracetamol (Tylenol), ibuprofen, and aspirin. NSAID medications inhibit prostaglandin.
- Contraception - the contraceptive pill often eases period pains, they cause thinning of the lining of the uterus, resulting in lower amounts of contraction during menstruation.
- Exercise - exercise has been found to help reduce the level of discomfort and pain experienced by women with period problems.
- Relaxation techniques - these can include breathing exercises, massage, and medication. Some women practice yoga for easing pain and stress.
- Hot water bottle - holding one against the abdomen may help in reducing discomfort.
- Warm bath - apart from helping the person relax, a warm bath may also provide some pain/discomfort relief.
Menstrual products used to absorb or catch the menses come in either disposable or reusable forms.
Disposable menstrual products
- Sanitary towels (sanitary napkins) - towels, pads, or napkins that are placed in the underwear and absorb the menstrual flow.
- Tampons - cylinders (long and tube like) made of treated rayon/cotton blends, or 100 percent cotton fleece. They are generally bleached. The woman/girl inserts it into her vagina. The menstrual flow is absorbed internally.
Reusable menstrual products
- Cloth pads - these are generally made of cotton, terrycloth, or flannel. They are placed externally.
- Menstrual cups - these are inserted directly into the vagina to catch the menstrual products and are reusable. There are also disposable versions.
- Reusable underwear - often called 'padded panties.' They are usually made of cotton with absorbent layers sewn on. They can be washed and reused.
- Blanket - also known as a towel or a draw sheet. These are large pieces of cloth which are more commonly used during sleep and are placed between the legs. They can be washed and used again.