BACKGROUND Aim of this work is to evaluate the different fatty acid composition of cervical mucus obtained during ovulation and at the term of pregnancy. METHODS The fatty acid composition in cervical mucus was determined in 14 non pregnant women during expected ovulation (cervical score > 10) and in 12 at term pregnant women. Following extraction, (acidification and transesterification), the identification and quantification of fatty acids was performed by gas-chromatographic analysis, with the aid of a specific software. RESULTS In both groups of samples, palmitic acid, stearic acid and oleic acid were the prevalent acids comprising more than half of the total amounts. Compared to non pregnant samples, in pregnant cervical mucus, elevated levels of oleic acid were pointed out, while mean levels of miristic acid and stearic acid were lower. In the samples of cervical mucus drew at the term of pregnancy, arachidonic acid levels mean values were higher when the first period of labour was started. CONCLUSIONS The pregnancy-induced biochemical changes in fatty acid pattern could likely be correlate to the variations of the physiochemical properties and to the physical appearance that cervical mucus undergoes during pregnancy. The elevated levels of arachidonic acid, during the first period of labour, may be correlated with prostaglandin production by intrauterine tissues (amniotic fluid, amnion, chorion, decidua, myometrium) and probably by cervical mucus.