Most women will experience period pain at some point in their life.
Period pain occurs during menstruation, and often involves painful cramps in the stomach, which may also occur in the thighs and back.
Period pain usually lasts for around 24 hours. In one in five cases, the pain is enough to stop sufferers doing everyday activities.
Period pains typically happen at the start of a period, although some women may begin to feel pain a few days before.
The pain is caused by the muscles in the womb contracting as menstruation begins. The constriction squishes blood vessels in the womb, depleting the local oxygen supply and setting off a natural reaction which causes the pain.
The pain is often felt as a cramp in the lower part of the stomach, but can also come in spasms or waves. Period pain isn't always limited to the stomach either and can spread to the thighs and back.
Some periods may be more painful than others, whilst there are other symptoms associated with period pains, including headaches, nausea, dizziness and feeling faint.
Research shows around 75% of young women experience period pain, with around 25% of adult women affected. Around 20% of cases are severe enough to prevent sufferers doing normal activities.
Period pain tends to decrease with age - whilst many women report period pains disappear after childbirth.
Several treatments are available for period pain - in most cases, this will be painkillers. The combined oral contraceptive pill may also help, whilst there are various things you can do at home to help prevent period pain in future.
Painkillers like ibuprofen and aspirin may help reduce period pain. These are anti-inflammatories, so they help to ease the cramps as well as reducing discomfort. Around 70% of women say ibuprofen or aspirin helps reduce the symptoms of period pain.
The combined oral contraceptive pill physically alters the womb. It thins the walls, so it's harder for an egg to stick and become fertilised. The positive effect for sufferers of period pain is that this means the womb walls do not have to contract as much, which should result in much less pain.
Taking a warm bath, or using a hot water bottle, can also help to reduce the discomfort, whilst exercise - such as swimming - can also help.
Yoga, or other relaxation exercises, will help calm your body and distract you, whilst in severe cases, a Transcutaneous Electronic Nerve Stimulation machine (TENS) can help block pain around the pelvic area.