By Maria Cendejas

A 30-year Swedish study shows birth control pills help relieve pain associated with menstruation or menstrual cramps, abcnews reports.

The study published on Tuesday in the journal Human Reproduction examined survey data on women, which were collected over a 30 year period to determine whether a combination of oral contraception pills alleviate symptoms of painful menstrual periods, also known as dysmenorrhea.

Researchers surveyed three groups of hundreds women aged 19 years in 1981, 1991 and 2001. The women were then checked again 5 years later. Birth control pills proved to lower pain more than age.

Ingela Lindh of the Institute of Clinical Sciences at Gothenburg University in Sweden, said in a statement, "By comparing women at different ages, it was possible to demonstrate the influence of [combined oral contraception] on the occurrence and severity of dysmenorrhea, at the same time taking into account possible changes due to increasing age. We found there was a significant difference in the severity of dysmenorrhea, depending on whether or not the women used combined oral contraceptives."

For decades, most gynecologists believed the pills have pain-relieving properties. But a review published in 2009 in the Cochrane Collaboration confirmed that there were only minimal evidence suggesting the oral contraceptions provide pain-relieving benefits.

"Gynecologists have been prescribing combined oral contraceptives for the last 40 years and for this indication. It was disappointing to see results of Cochrane. But gynecologists didn't feel that this proved that the pills weren't helpful, only that the studies hadn't yet been done to show it," said Dr. Paula Hillard, a professor at Stanford University School of Medicine of obstetrics and gynecology . 

The authors of the study reported that dysmenorrhea accounts for 600 million hours of work loss and $2 billion worth of productivity in the United States. 

"This is a well-done, informative study. The evidence is finally available to support what physicians see in their offices on a daily basis -- women with painful menses are indeed helped by being on a combined estrogen/progesterone pill to make the menses lighter and less painful in discharge," said Dr. Diane Harper, director of the Gynecologic Cancer Prevention Research Group at the University of Missouri-Kansas City. 

Menstrual cramps, which can be mild or severe, are common when women have their periods.  Each month, the inner lining of the uterus builds up to a point that allows a possible pregnancy.  After ovulation, if the egg is not fertilized and no pregnancy is possible, then as estrogen and progesterone hormone levels decline, the lining of the uterus become swollen and shed, which is how the menstrual flow forms.

Although birth control pills help menstrual pain or cramps, birth control pills or oral contraception pills always contain hormones, which are known to promote breast cancer growth.  As always, caution needs to be exercised  when you want to use hormones for whatever purposes.