Effect of delayed cord clamping on cerebral hemodynamics in preterm infants

Unstable cerebral hemodynamics is an important cause of intracranial hemorrhage in premature infants. The increased blood flow of delayed cord clamping (DCC) compared to immediate cord clamping (ICC) is equivalent to 1/3-1/4 of newborn blood volume. Our objective was to assess whether the increased blood flow causes fluctuations in cerebral blood flow and how.

This experiment was a prospective, observational study. Neonatologists selected preterm infants eligible for inclusion and exclusion, and divided them into DCC group and ICC group according to the way of umbilical cord ligation performed by obstetrics department, and matched them 1:1 according to gestational age. The peak systolic velocity （PSV) ，end diastolic velocity (EDV)，and resistance index (RI) of middle cerebral artery was measured by Mindray M9 color ultrasonic diagnostic instrument within 1 h, 24±1 h, 48±1 h, 72±1 h, respectively.

There was no significant difference in PSV, EDV and RI in middle cerebral artery between DCC group and ICC group (P > 0.05). There were no significant differences between groups and time (P > 0.05). The hemoglobin and hematocrit in DCC group were higher than those in ICC group within 2 h after birth (P < 0.05). (P > 0.05).

DCC can increase hemoglobin and hematocrit in preterm infants, but does not cause cerebral blood flow fluctuation within a certain range. DCC is a safe method of placental transfusion.