GSTM1 and polycythemia: However, we judged that lack of blinding was not likely to have any effect (low risk of bias) on the following outcomes: in-hospital mortality, initial hematocrit level, Hb level at birth, maximum serum bilirubin, any IVH, developmental quotient at 2 and 3.5 years of age, polycythemia, mean blood pressure at 4 hours, urine output in the first 24 hours, necrotizing enterocolitis, sepsis, spontaneous intestinal perforation, and Apgar score at 5 min.