The Pulmonary function tests were carried out in 70 normal pregnant women attending Antenatal clinic at government medical college Nanded. Out of 70 pregnant women, 16 were of first trimester, 22 were of second trimester and 32 were of third trimester. The aim of the study was to see whether any changes occur in pulmonary function tests in the 3 trimesters of pregnancy.The pregnant ladies were from age group of 16 to 30 years. Their weight and height were recorded. Using computerized med spiror instrument, following paramesters were studied i.e. FVC, FEV 1% FEV3, PEFR and MVV were recorded. 30 non pregnant women of same age group were taken as control group. The readings were compared of first and second trimester, second and third trimester and first and second trimester. Following observations were noted. PEFR was found to be significantly decreased in first trimester while other readings were not significantly decreased in first trimester as compared to second and third trimester. All the parameters also compared with control group. It showed that there was decline in all the values compared to control values, which was highly significant.