The Study Of Delayed Cord Clamping For Term And Preterm Infants

Objective To describe the duration of blood flow through the umbilical vessels after the delivery of single term fetus, and to evaluate the effect of different umbilical cord clamp timing on neonatal and maternal outcomes, and explore the optimal time of umbilical cord clamping for term and preterm infants.Methods In first part, we select 64 uncomplicated term vaginal deliveries from Dec. 2014 –Jan. 2015. Immediately after birth, arterial and venous umbilical blood flow was measured using Doppler ultrasound, duration and pattern of flow in umbilical vessels were evaluated until cord clamping.In second part, from Jan. 2015 –Jun. 2015, term mother-infant eligible pairs were selected and randomized by prenatal hemoglobin level and cord clamp timing(<15s, 30 s, 60 s, 90 s, 120 s, 150 s, 180s), preterm mother-infant eligible pairs were randomized to 4 groups by cord clamp timing(<15s, 60 s, 90 s, 120s). Sp O2 and HR recordings of term neonates with regular respiratory pattern were evaluated. Infant hematological status was evaluated at 24 h after birth. Transcutaneous bilirubin concentration and complications assessed at 72 h after birth. Duration of third stage of labor, and maternal blood loss were recorded. Follow infant hematological status at 6 months.Results 1. Venous flow: In 5 cases no flow was present, in 56 flow stopped at 187.5s(mean) after birth, before the cord was clamped. In 3 cases, flow continued until cord clamping. Initially, venous flow was intermittent, increasing markedly during large breaths or stopping and reversing during crying, but then became continuous.2. Arterial flow: In 5 cases no flow was present, in 57 flow stopped at 165.0s(mean), while cord pulsations were still palpable. In 2 cases flow continued until the cord was clamped. Arterial flow was pulsatile, unidirectional towards placenta or bidirectional to/from placenta. In 40% flow became continuous towards placenta later on.3. Infants subjected to delayed cord clamping had a higher SpO2 and lower HR in the first minutes after birth.4. For term infants, the mean Hb and Hct in DCC for 60 s, 90 s, 120 s, 150 s, 180 s group were significantly higher than ICC group; With the increase in the timing of delayed cord clamping, neonatal Hb and Hct at 24 hours was gradually increased. Before 90 s, the values increased rapidly, since then, almost unchanged.5. For preterm infants, the mean Hb and Hct in DCC for 60 s, 90 s, 120 s group were significantly higher than ICC group; With the increase in the timing of delayed cord clamping, neonatal Hb and Hct at 24 hours was gradually increased. Before 60 s, the values increased rapidly, since then, almost unchanged.6. No difference in adverse neonatal and maternal outcomes among groups.7. At 6 months of age, the term infants subjected to DCC groups had higher mean Hb levels and lower incidence of anemia, and the difference was more significant in prenatal anemia groups.8. At 6 months of age, the preterm infants subjected to DCC groups had higher mean Hb levels and lower incidence of anemia.Conclusion 1. After vaginal birth, venous and arterial umbilical flow duration were different. Net placental transfusion is probably the result of several factors of which breathing could play a major role. Umbilical flow is unrelated to cessation of pulsations. We consider the cut-off point of umbilical cord clamping at 180 s after birth.2. DCC can improve blood circulation of term infants through increasing placental transfusion, to help build neonatal respiratory cycle in early life. DCC do not increase the incidence of neonatal jaundice, polycythemia, and the risk of postpartum hemorrhage.3. Delayed cord clamping for 60 s to 90 s in term infants, and 60 s in preterm infants may be the proper time.4. DCC helps to reduce the incidence of anemia in infancy, particularly whose mother with anemia, it can be used as a viable conventional interventions.