The objective of this study is to investigate the impact of hormones on lung disease in Cystic Fibrosis (CF) patients. Due to improved therapies, CF patients are living longer and healthier lives than they did 20 years ago. However, females have been shown to have a survival disadvantage. The median life expectancy is 33 in women and 37 in men with CF. The hypothesis is that estrogen and/or progesterone negatively impact lung health in CF. Therefore, understanding the impact of sex hormones (including the use of birth control pills) on the disease process is increasingly important. The purpose of this study is to determine if lung function, respiratory symptoms, or various markers of lung health change during different phases of the natural ovulatory cycle in order to understand if estrogen or progesterone hormones are impacting the disease relative to fluctuations in men with stable testosterone levels. The research objectives of this project are to: