BackgroundIron deficiency anemia (IDA) is a major health problem during pregnancy and it has adverse effects on the mother and the newborn. Red cell distribution width (RDW), which is a quantitative measure for red cell size variation (anisocytosis), is a predictor of IDA. Little is known regarding RDW and IDA during pregnancy.MethodsA cross sectional study was conducted at the antenatal clinic of Khartoum Hospital, Sudan, to determine the performance of RDW in the diagnosis of IDA using serum ferritin as a gold standard.ResultsAmong 194 pregnant women with a gestational period of 21.4 ± 6.5 weeks, 57 (29.4%) had IDA according to serum ferritin levels (<15 μg/l) and 61 (31.4%) had IDA according to RDW (>14.5). The sensitivity, specificity, positive predictive value, and negative predictive value of RDW where serum ferritin was the gold standard were 43.8% (95% CI: 31.4–57.0%), 73.7% (95% CI: 65.8–80.5%), 41.0% (95% CI: 29.2–53.6%), and 76.0% (95% CI: 68.1–82.6%), respectively.ConclusionsIn this study, we found that RDW has a poor performance in diagnosing IDA among pregnant women compared with serum ferritin as the gold standard.Virtual slidesThe virtual slides for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/1721072967826303