Considered a drug by Health Canada, Mirena releases a synthetic form of the female hormone progesterone called levonorgestrel. "When a Mirena device migrates from the uterus, it can cause damage to organs in the abdomen and requires surgical removal," reads the document. "The Proposed Representative Plaintiff asserts that Bayer's failure to identify migration as a risk in the Mirena product monograph constitutes a breach of a duty to warn." According to the plaintiff, all women in Canada who used Mirena and experienced device migration during the class period should be included in the lawsuit against Bayer. Bayer argues that the class period should only start from 2008 until 2014 when "the Canadian Mirena product monograph was changed to address the risk of migration."