Our findings of a higher venous hematocrit values at 4 hours of age in the delayed cord clamping group indicates an effective placental transfusion at the time of birth when cord clamping is delayed. The finding is consistent with previous studies (12
). Although our sample size is small, the almost identical findings of various delivery room events suggest that the procedure of delayed cord clamping for a mean duration of 35 seconds is feasible and safe in this population. This is an important observation since many obstetricians are concerned that delaying the clamping of the cord may compromise the welfare of an infant during delivery.
We demonstrated that delayed cord clamping in this high risk population resulted in a trend toward a higher hematocrit values during the first 6 weeks, less need for transfusion during hospital stay and lower incidence of late onset sepsis and necrotizing enterocolitis (beneficial effects) as well as a higher incidence of intraventricular hemorrhage and retinopathy of prematurity (adverse effects). However, these beneficial and adverse outcomes of the intervention were all collected as secondary variables and were not powered for statistical significance in our sample size calculation. With reference to the higher hematocrit level at 6 weeks of age, Ultee et al recently showed that DCC is associated with a higher hematocrit levels in late preterm infants at 10 weeks of age when compared with those with ICC (20
) In a retrospective meta-analysis Rabe et al (17
) reviewed infants born below 37 weeks gestation and enrolled into a randomized study of delayed cord clamping (30 seconds or more) versus immediate cord clamping (less than 20 seconds) after birth.. Systematic search and analysis of the data were done according to the methodology of the Cochrane collaboration. They analyzed the results of 10 studies describing a total of 454 preterm infants which met the inclusion and assessment criteria. Major benefits of the intervention were higher circulating blood volume during the first 24 h of life, less need for blood transfusions (p=0.004) and less incidence of intraventricular hemorrhage (p=0.002). Recent studies have shown a lower incidence of late onset sepsis and intraventricular hemorrhage with delayed cord clamping (15
) based on the rationale that effective placental transfusion provided additional amount of stem cells that may confer additional immunologic competence (21
) for the former observation and additional blood volume that provides circulatory stability for the latter.
More recently, Hosono and coworkers introduced a novel method of ‘umbilical cord milking in lieu of delayed cord clamping to achieve placental transfusion for very preterm infants. The demonstrated that such procedure resulted in a higher blood pressure and urine outputs during the first 12 hours of life (23
), shorter duration of assisted ventilation a and less need for blood transfusion. (24
) Moreover, since it was known that umbilical cord blood contains various valuable stem cells such as haematopoietic stem cells, endothelial cell precursors, mesenchymal progenitors and multipotent/pluripotent lineage stem cells, the merit of delayed cord clamping has been magnified (25
It appears that in very preterm infants, placental transfusion achieved by delayed cord clamping or umbilical cord milking is a relatively inexpensive and safe intervention that could provide significant benefits. A single center large (sample size = 220) randomized controlled trial to test the hypothesis that delayed cord clamping will result in lower incidence of intravenricular hemorrhage and late onset sepsis is currently in progress at Women and Infants’ Hospital of RI (Judith Mercer, PhD, personal communication). Confirmation of the safety and benefits of delayed cord clamping by this clinical trial will provide an impetus to alter our practice of cord clamping during delivery of these high risk infants.