Relationship of fetal plasma and amniotic fluid EPO in pregnancies complicated by preeclampsia or hypertension grouped by amniotic fluid EPO concentration: A) low EPO<20 mU/ml, r=0.87, p<0.0001, n=28; B) slightly elevated EPO 20–50 mU/ml, r=−0.10, p=NS; n=13; and C) high EPO >50 mU/ml, r=0.86, p<0.0001, n=17. (Reproduced with permission from Neonatology 2009; 95:105–116.)