In order to keep the normal pregnancy, a number of gene products are required at the feto-matemal interface. We have isolated approximately 30 genes, involved in keeping the normal pregnancy, via subtractive hybridization and RT-PCR analyses of cDNAs from the chorionic villi of normal and RPL patients. Characterizing their functions will help us to understand the process of establishing and maintaining pregnancy. In addition, more detailed studies of their expression in normal and RPL patients are required to evaluate their clinical relevance. Further identification of genes aberrantly expressed in RPL patients will help the prognosis of the pregnancy, identifying pregnancies with a high risk of miscarriage and enabling management of those pregnancies.