WEDNESDAY, Feb. 25 (HealthDay News) -- A women's own reproductive hormones may help protect her from developing Parkinson's disease, a new study finds.

Women with a longer fertile lifespan (the time from first menstruation to menopause) have a lower risk of the neurological disease, according to the findings released Wednesday and scheduled to be presented at the American Academy of Neurology's annual meeting in late April in Seattle.

Hormone replacement therapy did not seem to add any level of protection, the researchers noted.

"These findings suggest that longer duration of exposure to the body's own [endogenous] hormones may help protect the brain cells that are affected by Parkinson's disease," study author Dr. Rachel Saunders-Pullman, of Albert Einstein College of Medicine in New York City, said in a news release from the American Academy of Neurology.

Researchers have long believed a women's hormones may affect her chances of developing the disease. Parkinson's is much more common in men than women.

The study, which looked at nearly 82,000 postmenopausal women, also found that women with four or more pregnancies had a 20 percent greater risk developing Parkinson's than women with fewer pregnancies, a finding that Saunders-Pullman said needed more study.

Women who had hysterectomies (known as "menopause from surgery") had nearly double the odds of developing Parkinson's if they had used hormone therapy before surgery, compared to if they had never taken hormone therapy. No change in risk was apparent for those who used hormone therapy during their natural menopause.

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