The Primigravid and Nulliparous pregnant women are prone to multisysystemic pregnancy problems. The aim of this study was to assess lung function pattern in all trimesters of pregnancy and two days post partum for Primigravida and Nulliparous women as compared with that of control group i.e, non pregnant women. Ethical clearance and informed consent were obtained from the Ethical Committee of the St philomena’s Catholic hospital. The study consists of recording the FVC and FEV1 of four groups of female subjects including pregnant women of various phases of gestational period i.e., 13th week, 24th week and 37 the week and control group of non-pregnant women using computerized Spirometer ( Spirolab II Italy). Progesterone was assayed using standard laboratory method.The study revealed a statistically significant increase in FVC , FEV1 and Progesterone (p < 0.001) in both the Primigravid and Nulliparous pregnant women in all the trimesters of pregnancy and two days post partum when compared to control.In these groups of pregnant women, the anxiety of first pregnancy may release adrenaline. Adrenaline has a dilating effect on the bronchial smooth muscle. In addition, the strength of the abdominal muscle is expected to be high in these subjects. In addition, progesterone a pro-pulmonary function hormone was higher in the pregnant women. These effects may have overwhelmed the negative effect of the mechanical pressure of the gravid uterus on pulmonary function. Primigravid and Nulliparous women may have an improved pulmonary function compared to control. Key words: Forced Vital Capacity (FVC), Forced Expiratory Volume in 1 sec (FEV1), Spirometry, Pregnancy.