This issue of the Obstetrics and Gynecology Clinics in North America will focus on the advances in the evaluation and management of Recurrent Pregnancy Loss (RPL) that have emerged within the last few years. Although spontaneous pregnancy loss occurs in approximately 15% to 20% of clinically recognized pregnancies in reproductive-aged women, RPL occurs in 2% to 5% of the same population. Recent reports on large populations of women with RPL have helped to characterize the incidence and diversity of this heterogeneous disorder, and a definite cause of pregnancy loss can be established on...