Abstract: In accordance with the present invention, recombinant human PBEF has been produced in order to study its ability to stimulate the transcription of the key cytokine mediators of labor induction, using the amnion-like epithelial (WISH) cell line and fetal membrane explants. As a result of these studies, it has been determined that PBEF is a good indicator of initiation of labor. This makes PBEF a useful marker, especially for the identification of subjects who have initiated preterm labor. Accordingly, methods for the identification of subjects who have commenced labor are provided. In addition, methods are also provided for blocking labor, as well as compositions useful therefor. This is accomplished by blocking the production of PBEF or by blocking the action of PBEF.