The effects of cigarette smoking on pulmonary function tests during pregnancy

Objective: The objective of this study was to determine what changes occur in pulmonary function testing in pregnant women who smoke versus nonsmokers.Methods: This was a prospective study. Pregnant women were recruited in all trimesters of pregnancy. A total of 34 women (15 smokers, 19 nonsmokers) were recruited. Measurements of forced vital capacity (FVC), forced expiratory volume in one second (FEVI), the ratio of FEVI to FVC, and maximum voluntary ventilation (MVV) were obtained.Results:Conclusions: This study confirms other studies that have seen no significant changes in FVC, FEVI, FEVI/FVC in pregnant smokers and nonsmokers. A significant worsening in MVV was seen in pregnant women who smoke. The pathophysiologic impact of this effect is unclear. However, since MVV is a measure of the bellows action of the chest, this may lead to a decrease in oxygenation during the active phase and the second stage of labor. This may lead to more abnormal fetal monitoring strips and possibly lower Apgar scores. Further investigation will be necessary to clarify the effects on pregnancy of lower MVV in patients who smoke.