Two systematic reviews, three randomized controlled trials, and four non-randomized, studies were identified describing the clinical effectiveness of intravenous immunoglobulin for the treatment of recurrent spontaneous abortion. One systematic review of good quality, one randomized controlled trial of good quality, two randomized controlled trials of moderate quality, and one non-randomized study of limited quality found no difference in live birth rates between patients with recurrent spontaneous abortion treated with intravenous immunoglobulin compared to placebo or other treatments. One systematic review of good quality, one non-randomized study of moderate quality and two non-randomized studies of limited quality reported a significant improvement in rates of live birth for participants with recurrent spontaneous abortion treated with intravenous immunoglobulin compared to participants not receiving intravenous immunoglobulin. Of five included studies reporting on either adverse events or side effects, no serious adverse events were reported, with four studies reporting minor side effects in some patients treated with intravenous immunoglobulin compared to controls. Obstetric, perinatal, and neonatal outcomes were reported in four included studies, with no important clinical differences identified between treatment groups. The authors of most included studies suggested that additional evidence from larger, randomized studies remains necessary to reduce uncertainty concerning the clinical effectiveness of intravenous immunoglobulin to patients with recurrent spontaneous abortion.