A sub-analysis of women without pre-delivery anemia (Hb ≥ 10.5 g/dl; N = 66 and N = 227 in the control and PPH groups, respectively) showed a similar decrease in the control versus the PPH group of both Hb [1.1 ± 1.3 g/dl (median 0.85 g/dl, IQR 0.3–1.5 g/dl) versus 2.5 ± 1.6 g/dl (median 2.4 g/dl, IQR 1.3–3.6 g/dl), p < 0.0001; respectively] and HCT [3.3 ± 3.7% (median 2.6%, IQR 0.6–5.2%) versus 7.3 ± 4.6% (median 7.3%, IQR 3.6–10.7%), p < 0.0001; respectively]. The gene discussed is GSTM1; the disease is pulmonary arterial hypertension.