The menstrual cycle is a monthly series of occurrences and changes that a woman’s body goes through in preparation for a possible pregnancy. It involves release of an egg from the ovaries each month, a process known as ovulation, along with a series of hormonal changes that prepare the uterus for pregnancy.
However, in absence of fertilisation of the egg, the uterus sheds its thickened lining through the vagina, a process known as the menstrual period.
What a normal menstrual cycle looks like
The menstrual cycle is counted from the first day of a period to the first day of the next period. However, it is not exactly the same for every woman, and menstrual flow may occur between 21 days to 35 days in different women, and lasts anywhere between two to seven days. Menstruation cycles tend to be long in the first few years after they begin post puberty but generally shorten and become more regular with age.
Some women may have extremely regular cycles, with period occurring about the same time every month, while some women may experience somewhat irregular cycles. Menstruation may be accompanied by pain or be pain-free, could be light or heavy bleeding, long or short – all these could be normal in different women.
Menstrual cycle: What exactly happens in the body
Once a month, a tiny egg or ovum is released from the ovarian follicles in one ovary. This process is known as ovulation. The released egg travels down the fallopian tube that connects the ovary and uterus, and reaches the uterus.
In days prior to ovulation, the hormone oestrogen levels rise in the body, directing the uterus to thicken its wall lining with extra blood and tissue, cushioning it in preparation for receiving the egg. If the travelling egg is fertilised by a sperm as it travels through the fallopian tube, it reaches to the uterus and attaches itself to the thickened uterine wall.
If the egg isn’t fertilised during its journey through the fallopian tube, like in case of most monthly cycles, the egg does not attach itself to the uterus. Hormone progesterone levels, which are running high at this point, begin to drop. This directs the uterus to shed its lining. The uterus lining, blood, tissue and unfertilised egg leave through the vagina and form the monthly menstrual period.
This cycle repeats every month (except when a woman is pregnant) till a woman reaches menopause that stops the release of eggs from ovaries.
Menstruation: What to expect when entering puberty
Menstruation or period is a major stage of puberty in young girls, and is a significant physical sign of a girl entering womanhood. Like other changes, it can be confusing and cause anxiety in some. Without a proper understanding of a woman’s reproductive system or the menstrual cycle, the process may appear mysterious.
Puberty usually begins between the ages of eight and thirteen. Hormones in the body of a young girl stimulate various physical developments, like growth and breast development. Internally, the ovaries get ready to release their first egg, marking the start of menstrual cycle.
The start of periods is known as menarche, and it does not happen till a girl’s reproductive system has matured and is functional. These changes include
- Release of hormones from pituitary gland to stimulate ovaries
- Production of hormones oestrogen and progesterone by ovaries
- Physical changes in a girl’s body, like development of breast and release of vaginal discharge
Once menarche commences, the changes associated with menstrual cycle start taking place every month.
Tracking the menstrual cycle
A normal menstrual cycle may be different for every woman and it is best to understand one’s cycle by keeping a record of the different changes with the help of a calendar or digital application.
The following parameters regarding a period must be noted for a menstrual cycle:
- Start date – A menstrual cycle is counted from the first day of the period.
- End date – How long a period lasts, and whether it was shorter or longer in a particular month, helps to chart what’s normal and calculate other events like ovulation.
- Flow – Is the flow heavy or light?
- Abnormal bleeding – Bleeding in the middle of a cycle between two periods must be brought to a doctor’s attention.
- Pain – Some pain accompanies a period in many women. However, its severity and duration must be noted for any abnormality.
Menstrual cycle irregularities
Irregular menstrual cycles may have different causes. These include:
- Pregnancy or breastfeeding – A missed period may signal pregnancy. After birth of a baby too, the menstruation gets delayed due to the effects of breastfeeding.
- Eating disorders or lifestyle habits – Anorexia or excessive exercising can disrupt menstruation.
- Polycystic ovary syndrome (PCOS) – It is a hormonal disorder that causes small cysts on the ovaries and irregular periods.
- Pelvic inflammatory disease (PID) – It is an infection of the female reproductive organs.
- Uterine fibroids – These are non-cancerous growths of the uterus that cause heavy periods or bleeding between periods.
- Premature ovarian failure – This refers to loss of normal ovarian function before the age of 40.
Premenstrual syndrome (PMS)
Some girls and women may experience irritability, a feeling of sadness or emotional outbursts, a little more than usual during the few days or week before their periods. Some develop craving for certain foods. These emotional and some physical changes are related to the changes in the body’s hormones and are called premenstrual syndrome (PMS).
Rising hormone levels cause certain physical changes too, like a bloated feeling due to water retention, sore breasts, headaches, or acne in young women. PMS symptoms usually disappear with the appearance of periods.
Eating right and healthy foods, getting sufficient sleep and exercising can help relieve some of the symptoms of PMS.
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“Menstrual cycle: What’s normal, what’s not,” MayoClinic.com, Mayo Clinic Staff, http://www.mayoclinic.org/healthy-living/womens-health/in-depth/menstrual-cycle/art-20047186?footprints=mine&pg=1
“Menstrual cycle,” NHS.uk, http://www.nhs.uk/livewell/menstrualcycle/Pages/menstrualcyclehome.aspx
“Menstruation and the menstrual cycle fact sheet,” WomensHealth.gov, http://www.womenshealth.gov/publications/our-publications/fact-sheet/menstruation.html
“Puberty and Periods,” KidsHealth.org, The Nemours Foundation, http://kidshealth.org/teen/sexual_health/girls/menstruation.html
“When Your Period Signals a Problem,” WebMD.com, Stephanie Watson, http://www.webmd.com/women/features/when-your-period-signals-problem
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