BACKGROUND Women using copper intrauterine devices (IUDs) frequently experience bleeding abnormalities. This review was conducted to evaluate the evidence regarding whether hemoglobin levels should be measured prior to copper IUD insertion. STUDY DESIGN The PubMed database was searched from database inception through March 2012 for all peer-reviewed articles in any language concerning hemoglobin changes among women with anemia who have copper IUDs inserted. Articles were included if they reported changes in hemoglobin among anemic women over a specified period of time following copper IUD insertion. Articles were excluded in which there were no women with anemia at baseline or outcomes among women with anemia were not reported separately. For indirect evidence, articles were included which addressed hemoglobin changes among women without anemia who had copper IUDs inserted. The quality of each direct study was assessed using the US Preventive Services Task Force grading system. RESULTS Four level I to II-2 studies of fair quality met inclusion criteria as direct evidence. Evidence from one randomized trial and one prospective cohort study showed no statistically significant changes in hemoglobin among copper IUD users with anemia, while two prospective cohort studies showed a statistically significant, but clinically small, mean decrease in hemoglobin levels over 12 months of follow-up. We also identified 21 studies examining changes in hemoglobin among healthy women using copper IUDs as indirect evidence; this body of evidence was not graded. These studies generally showed no clinically significant changes in hemoglobin levels with up to 5 years of follow-up. CONCLUSIONS Limited fair-quality evidence was mixed but generally showed no clinically significant changes in hemoglobin among women with anemia who used copper IUDs for up to 12 months. Indirect evidence among healthy women using copper IUDs did not show clinically significant changes in hemoglobin levels when followed for up to 5 years of use.