Each month, women avoiding pregnancy breathe a sigh of relief when they get their period, while those trying for a baby cross their fingers that it won’t come.
But pregnancy is not the only reason a woman can stop, or never start, having periods, and it can be a sign of underlying health problems.
An absence of a period is known as amenorrhea. Here are four causes of amenorrhea.
Intense strain on the body affects the hypothalamus: a part on the brain that helps to regulate hormones. This can cause ovulation to stop.
Women can experience hypothalamic amenorrhoea for many reasons. Women who are around 10 per cent underweight; athletes and women in other jobs which put their bodies under pressure; and stress can trigger the condition. These include being around 10 per cent underweight, according to the Mayo Clinic.
Polycystic ovary syndrome (PCOS)
Millions of women are thought to have this little spoke of condition, according to the NHS. In those PCOS, the sacs in which eggs develop do not form properly and become cysts. This renders the ovaries unable to release eggs and menstruation cannot start.
It is unclear what causes the condition, but it is believed to be hereditary, and linked to abnormal levels of hormones in the body.
This condition is triggered by an excess level of prolactin: a hormone which enables women to produce milk. The spike in prolactin can be caused by a tumour, pregnancy, or medications which interfere with hormones. Both men and women can experience this. Women with this condition secrete milk from their breasts, experience a loss of libido as well as seeing their periods stop.
Women whose ovaries stop working before they reach menopausal age no longer have periods. This happens to around 1 in 100 women below the age of 40-years-old.
Ovarian failure is accompanied by the symptoms of menopause, including hot flushes, night sweats, vaginal dryness, reduced sex drive, and anxiety.
An irregular thyroid
If the gland which regulates the metabolism is not functioning properly, this can have a knock on effect for the other systems in the body. In turn, ovultion can stop.
Visit the NHS website for more information on amenorrhea.
Join our new commenting forum
Join thought-provoking conversations, follow other Independent readers and see their replies