Physiological cord clamping improves placental transfusion and infant iron stores compared with one-minute delayed cord clamping during cesarean delivery

Background Delayed cord clamping (DCC) improves neonatal iron stores, but placental transfusion during cesarean delivery may remain incomplete. Physiological cord clamping (PCC), performed after cessation of umbilical blood flow, may optimize placental transfusion. Methods 240 women with uncomplicated term singleton pregnancies undergoing cesarean delivery were assigned to DCC at 1 minute ( n = 120) or PCC (n = 120). Immediate neonatal outcomes were assessed in all participants, while hematological outcomes at 6 months were evaluated in 98 infants in the DCC group and 94 in the PCC group. Correlation and multivariable regression analyses identified predictors of hematological outcomes. Results The mean cord-clamping interval was longer with PCC (5.79 ± 0.73 vs 1.27 ± 0.16 min; p < 0.001), with lower residual placental blood volume (10.47 ± 4.38 vs 31.24 ± 6.25 mL; p < 0.001). PCC resulted in higher neonatal hemoglobin (19.74 ± 3.04 vs 17.27 ± 3.19 g/dL) and hematocrit (59.54 ± 6.02% vs 54.78 ± 5.43%) at 24–48 hours, and higher hemoglobin (11.90 ± 1.21 vs 10.46 ± 1.35 g/dL), hematocrit (35.19 ± 2.91% vs 32.62 ± 4.18%), and serum ferritin (median 107.0 vs 48.9 ng/mL) at 6 months (all p < 0.001). Adverse neonatal outcomes were comparable between groups. In exploratory treatment-adjusted analyses, PCC remained associated with higher neonatal hemoglobin and hematocrit, while residual placental blood volume was inversely associated with hemoglobin at 6 months. Conclusions Physiological cord clamping was associated with greater placental transfusion and higher neonatal hemoglobin and hematocrit levels, with improved iron stores at 6 months, compared with 1-min delayed cord clamping. These findings suggest potential neonatal hematological benefits of physiological cord clamping. Larger multi-center randomized trials with longer follow-up are needed to confirm these findings and establish its safety, feasibility, and clinical benefit before routine clinical implementation.