As premature infants have been increasing interestingly with high prevalence of complication among them, early prediction of preterm labor became crucial. Prediction of preterm labor is based on identification of risk factors detection and levels of many biochemical markers either in maternal serum as alpha fetoprotein, ceruloplasmin, corticotropin releasing hormone and metalloproteinase-9 or in cervicovaginal discharge as fetal fibronectin, interleukin- 8 & 6, phosphorelatd insulin growth factor binding protein-1 and interferon can be used for prediction. Moreover, diagnosis of bacterial vaginosis and maternal salivary estriol are useful markers. In addition, transvaginal ultrasonogrphic assessment of a woman’s cervix is a valuable tool for diagnosis of cervical incompetence and preterm labor. Finally, new molecular techniques for identifying expressed genes could provide new insights for prediction of preterm labor.