Effect of menstrual cycle on pulmonary functions and respiratory efficiency

Background: The cyclic hormonal changes during different phases of menstrual cycle are responsible for various physiological changes including its diverse role on reproductive organs. Their effects on extra-reproductive systems like airway dynamics and respiratory efficiency are very few in literature. Aim: To evaluate the effects of menstrual cycle on various parameters of lung functions and respiratory efficiency in young females. Materials and methods: 75 young non-pregnant females of age group 18-30 years were selected randomly for this study. Their menstrual phases were estimated based on menstrual history questionnaires and last date of menstrual bleeding, namely, menstrual, follicular and luteal. Their pulmonary function tests and respiratory efficiency was measured using computerized spirometer thrice in each phases of menstrual cycle. The various parameters evaluated were: forced vital capacity (FVC), forced expiratory volume in 1st sec (FEV1), Maximum mid expiratory flow rate (MMEFR), peak expiratory flow rate (PEFR), maximum voluntary ventilation (MVV), 40 mm respiratory endurance test (RET), breath holding time after full expiration and maximum inspiration (BHT ex and BHT ins) and maximum expiratory pressure (MEP). Results: FVC, FEV1, and MMEFR were significantly higher during the luteal phase as compared to menstrual and Follicular phase; whereas PEFR and MVV were significantly higher during the luteal phase as compared to menstrual phase only. On respiratory efficiency tests the BHT ex, BHT ins and MEP were significantly higher during the luteal phase as compared to menstrual and Follicular phase; also it was observed that BHT ex were significantly higher during the follicular phase as compared to the menstrual phase. Conclusion: Respiratory efficiency and pulmonary functions parameters were higher during the luteal phase of menstrual cycle. Main reason behind this could be the progesterone hormones’ effect on respiratory apparatus, whose levels remains on higher side during the luteal phase.