RESUMEN
Background & objectives: Cyclical changes in the hormonal levels determine different phases of menstrual cycle. These variations in hormonal levels are also responsible for variations in functional parameters of many systems in the body. Many studies have highlighted the changes in respiratory parameters in different phases of menstrual cycle. In this study, we have explored the factors that influence lung function in adolescent girls focusing on the hormonal factors related to the menstrual cycle. Methods: 36 adolescent girls with normal menstrual cycle consented for the study. Pulmonary functions and serum progesterone were measured during follicular and secretory phase of menstrual cycle after a detailed menstrual history and screening for medical illness. Results : show a significantly higher serum progesterone and FVC, FEV1 and PEFR during secretory phase. There was a strong positive correlation of Serum progesterone in secretory phase with FVC and negative correlation with FEV1%. Interpretation & conclusion: This improvement of pulmonary function during secretory phase is due to increase in serum progesterone levels which have a dual effect of overall smooth muscle relaxation and hyperventilation. Supplement of progesterone may be useful to avert premenstrual asthma and enhance the performance.