Objectives: To compare the pulmonary function and the body composition between trimesters of pregnancy and, to determine the variables correlated to the peak expiratory flow (PEF) and the expiratory flow between 25% and 75% of vital capacity (FEF 25%75% ).
Methods:A cross-sectional study examined 120 healthy low-risk pregnant women in the three trimesters of pregnancy, measured by spirometry and multisegmental electrical impedance. Women between the fifth and 40th gestational week, ages between 18-35 years, singletons, and sedentary were included. Smokers, individuals with cardio-respiratory diseases, neurological and chest deformities were excluded. For data analysis, descriptive statistic was used to characterize the sample and analysis of variance for comparing the groups with post hoc Tukey test. The correlation between the independent variables and the flow was performed by Pearson correlation coefficient. Multiple linear regression was used to estimate the degree of relationship between the dependent and independent variables.
Results:The vital capacity, the expiratory volume in one second, the peak expiratory flow and expiratory flow between 25% and 75% of vital capacity decreased with the progression of pregnancy, but no significant statistically difference was found. An increase of the current weight (p <0.02) and BMI (p <0.003), total body water (p < 0.04), extracellular water (p <0.03), fat mass (p <0.04) and fat-free mass (p <0.04) was observed during the gestational trimesters. There were correlations between PEF and FEF 25%75% with some variables, such as maternal age, height, pre-pregnancy weight, total body weight and extracellular water, lean mass and fat-free mass. The multiple linear regression analysis showed that height and maternal age were