 Recruited subjects will be asked to record asthma symptom scores, morning Peak Expiratory Flow Rate m-PEFR and rescue asthma medication β2-agonist used daily during the one month screening period to identify women with and without pre-menstrual asthma. Asthmatic women with regular menstrual cycles will be evaluated in their follicular phase days 5-8 and luteal phase days 21-24 and women on oral contraceptive pills OCP will be evaluated on days 9-12 of their OCP cycle and during the days 25-28, off of OCP consecutively for a 2-month period. 