Taking birth control pills may stabilize knee joints and reduce the risk of injuries, suggests a McGill University study.The researchers assessed the knee stability of 78 female athletes -- 42 were taking birth control pills and 36 were not -- by using a device called an anthrometer to measure any displacement of the women’s knees.The women who were taking birth control pills had much less displacement than the women who weren’t taking the pill, indicating tighter knee joints that may be less susceptible to ligament tears or injuries, they said.