Abstract Fourier Transform Infra-red (FTIR) Spectroscopy is a non-invasive, reagent free diagnostic tool in the analysis of biological fluids. The results can be best employed in the qualitative and quantitative investigation of biological fluids. FTIR spectroscopy is employed for analyzing the absorption level of progesterone in humans. FTIR spectroscopic technique has been successfully applied to analyze the saliva samples. The present research aims to analyze the changes occur during pregnancy and the study attempts to evaluate the spectral difference between saliva of non-pregnant and pregnant women during 1st trimester (6 weeks and 12 weeks). FTIR spectroscopic technique has been successfully applied to detect the biochemical alterations present in the saliva. FTIR saliva spectra were recorded over the region 4000 to 400cm-1 on a Perkin Elmer spectrum one FTIR spectrometer. The internal standard ratios among the absorption peaks were calculated and it is found to be an indicator to find the changes occur in the salivary pattern of normal pregnant and non-pregnant women . In order to find the efficacy, the absorption values of the specific bands of the spectra in the 1st trimester during 6 weeks and 12 weeks were noted and the vibrational peaks of HCG, Lipids, Thiocyanate, Progesterone, Phospholipids of Proteins, and Collagen were found .and internal ratio parameter were calculated. In this study comparative analysis of saliva is used to detect the early pregnancy during 1st trimester and the comparison of these values showed that the spectra are not similar when compared with non-pregnant and normal pregnant women during 6 weeks and 12 weeks of pregnancy. The absorbance value of hCG and progesterone increases in pregnant women (6 weeks and 12 weeks) compared to non-pregnant women. Saliva will inform whether a woman is pregnant and in this study saliva plays a vital role to detect early pregnancy.