Lung function and airways responsiveness during pregnancy

ABSTRACT

The changes in forced vital capacity [FVC], forced expiratory volume in the first second [FEV[1]], peak expiratory oral pressure [PEFR] and abdominal birth pregnancy and in the postpartum period were found. A randomized prospective longitudinal study was performed in Rabak city in central Sudan in January to November 2002. 48 normally pregnant women were included [26 in the 3[rd] trimester, 19 in the 2[nd] trimester and 3 in the 1[st] trimester]. The microplus spirometer was used to measure FVC, FEV[1] and PEFR during pregnancy then 1-2 months after delivery. The abdominal girth was measured concurrently with lung function parameters. Paired T-test was used to compare lung function during pregnancy and in postpartum period. The results show that there was significant increase in both FVC and FEV[1] after delivery [P<0.01] with insignificant increase in PEFR. The abdominal girth had decreased significantly in the postpartum period [P<0.01]. In spite of the steady drop in FEV[1] from the 1[st] to the 3[rd] trimester, PEFR values showed some what steady increase. There was no significant correlation between abdominal girth and lung function during pregnancy. Some pregnant women had reported dyspnea. It was concluded that there was significant reduction in FVC and FEV[1] values during pregnancy compared to postpartum period which can not be only explained mechanically, because this decrease had occurred from the 1[st] trimester even before any increase in the abdominal girth. The improvement in PEFR values from the 1[st] to the 3[rd] trimester can be explained by the rise of plasma cortisol and this improves asthma severity during pregnancy. The reported dyspnea during pregnancy can be explained by the hyperventilation during pregnancy caused by progesterone and not mechanically, because it frequently occurred before any increase in the abdominal girth