BackgroundIron deficiency is a common problem in subfertile women. The influence of iron status on unexplained infertility is unknown.MethodsIn a case-control study, 36 women with unexplained infertility and 36 healthy non-infertile controls were included. Parameters of iron status including serum ferritin and a serum ferritin <30 µg/dL served as main outcome parameters.ResultsWomen with unexplained infertility demonstrated a lower transferrin saturation (median 17.3%, IQR 12.7-25.2 versus 23.9%, IQR 15.4-31.6;p=0.034) and a lower mean corpuscular hemoglobin concentration (median 33.6 g/dL, IQR 33.0-34.1 versus 34.1 g/dL, IQR 33.2-34.7;p=0.012). Despite the fact that there was no statistically significant difference in median ferritin levels (p=0.570), women with unexplained infertility had ferritin levels <30µg/L more often (33.3%) than controls (11.1%;p=0.023). In a multivariate model, unexplained infertility and abnormal thyroid antibodies were associated with ferritin <30µg/L (OR 4.906, 95%CI: 1.181-20.388;p=0.029 and OR 13.099; 2.382-72.044;p=0.029, respectively).ConclusionFerritin levels <30µg/L were associated with unexplained infertility and might be screened in the future. Further studies with a focus on iron deficiency and iron treatment on women with unexplained infertility are warranted.