Abdominal pain before a period begins can be part of a set of symptoms called premenstrual syndrome--PMS, which according to Medline Plus, over 75 percent of women experience in their reproductive years. However, there are many other causes of these symptoms and they should never be self-diagnosed.
During the early days and weeks following conception it is common for a woman to feel slight abdominal cramping. When a woman first becomes pregnant, the fertilized egg rapidly divides, attaching to her uterine wall. When this implantation occurs, some women experience slight bleeding and cramping. This bleeding is lighter than a period and is known as implantation bleeding or spotting. When pregnancy first occurs, many women are not even aware of the pregnancy until they miss their menstrual period. They may also experiences the classic first trimester symptoms, which are lower abdominal cramps, food cravings, nausea, morning sickness, swollen breasts, fatigue, frequent urination and mood swings. However, report severe abdominal cramping following heavy bleeding, as it is not a regular symptom of pregnancy.
Reproductive diseases such as endometriosis and polycystic ovary syndrome can both cause cramping and a delay in menstruation. Endometriosis causes the uterine lining to grow outside of the uterus on places such as the abdomen, ovaries, colon and bladder. When a woman's period normally occurs, the built-up uterine tissue in the uterus begins to shed and bleed. In women with endometriosis, the uterine tissue outside of the uterus also swells and bleeds, but does not shed. This blood may irritate the surrounding tissues causing cramping. Polycystic ovary syndrome--PCOS--causes the ovaries to become enlarged and polycystic--containing many cysts. Researchers are not sure of what causes this condition, but they blame the overproduction of cysts on a higher than normal level of luteinizing hormone. This hormone partially controls menstruation and ovulation.
Midway through the menstrual cycle, levels of the hormones estrogen and progesterone surge, which causes a follicle in the ovary to rupture and release an ovum, or egg. When this occurs, some women feel slight cramping, called mittelschmerz. Although the cause of the pain is not fully understood, researchers explain that it may be due to the follicle stretching the surface of the ovary prior to ovulation, or the fluid being released from the ovary during ovulation, irritating the abdominal lining.
Sometimes abnormal menstrual cycles and abdominal pain can be due to uterine growths that disrupt the way the uterus functions; one common uterine growth is called a uterine fibroid. Uterine fibroids can hang from the uterine cavity or grow in the uterine muscle or lining. These polyps can be as small as seeds or large enough to take up the whole inside of the uterus. According to MedlinePlus, these uterine growths are experienced by 1 in 5 women during their childbearing years.
Seek emergency care if heavy bleeding or extreme cramping occurs. Although cramping and lack of a menstrual period can be attributed to minor causes, it can also be attributed to other conditions such as a tubal pregnancy or cervical cancer.