Seikku L, et al. - In view of a higher risk of perinatal morbidity and mortality in pregnancies beyond 41 gestational weeks, researchers evaluated erythropoietin (a hormone regulating erythropoiesis and a biomarker of chronic fetal hypoxia) levels in amniotic fluid and umbilical cord serum in an apparently low-risk term (≥ 37 gestational weeks) and prolonged pregnancies (≥ 41 gestational weeks) with labor induction. In this prospective cohort study, they included 93 singleton pregnancies at 37⁺⁰-42⁺¹ gestational weeks, of which prolonged pregnancies numbered 63 (67.7%). Erythropoietin levels in amniotic fluid correlated with the levels in umbilical cord serum in vaginal deliveries. A correlation between erythropoietin levels and gestational age was evident, probably due to weakening placental function and relative hypoxemia occurring in advanced gestation. However, this relatively low-risk study population displayed had no adverse delivery outcome in correlation with erythropoietin.