This Cochrane Review examines the effects of different policies for clamping the umbilical cord after birth for babies born at term. It compares early cord clamping, which usually takes place within 60 seconds of birth, versus later clamping that usually involves clamping the cord more than one minute after birth or when cord pulsation has ceased.
In the past, the umbilical cord has usually been clamped shortly following the birth of the baby, as part of the active management of the third stage of labour. This strategy might also involve the infant being placed on the mother’s abdomen, put to the breast or more closely examined on a warmed cot if resuscitation was required. However, more recent guidelines for management of the third stage of labour no longer recommend immediate cord clamping, and later clamping of the umbilical cord might take place when cord pulsation has ceased or beyond the first minute following the birth of the baby. However, there is ongoing uncertainty about the relative benefits, or harms, of the two approaches. There have been concerns that late cord clamping might increase the mother’s risk of a postpartum haemorrhage, that could outweigh potential benefits to the baby of delaying clamping which might arise from the extra time for a transfer of the fetal blood in the placenta to the infant at the time of birth. This placental transfusion can provide the infant with an additional 30% more blood volume and up to 60% more red blood cells.
The authors of this updated Cochrane Review searched the Cochrane Pregnancy and Childbirth Group’s Trials Register in February 2013. This Register is maintained through electronic searching of the Cochrane Central Register of Controlled Trials, MEDLINE and EMBASE; along with dedicated searching of dozens of journals and the proceedings of major conferences. After checking 74 reports representing 58 studies, they excluded 37 studies and included 15 in the review. A further 4 studies are awaiting assessment and 2 ongoing studies were also identified. The 15 included randomized trials recruited a total of 3911 mother and baby pairs.
The primary outcome measures for the review included maternal death and severe maternal morbidity as a composite outcome, but none of the included studies reported data on these. However, in the five trials (2066 women) that reported another of the primary outcome measures, severe postpartum haemorrhage (PPH) (blood loss of ≥1000 ml blood), there were no significant differences between early versus late cord clamping (risk ratio (RR): 1.04, 95% confidence interval (CI): 0.65 to 1.65). There were also no significant differences for PPH of ≥500 ml (RR: 1.17, 95% CI: 0.94 to 1.44, 5 trials, 2260 women), mean blood loss (mean difference (MD): 5.11 ml, 95% CI: -23.18 to 33.39, 2 trials, 1345 women), or maternal haemoglobin values at 24 to 72 hours after the birth (MD: -0.12 g/dl, 95% CI: -0.30 to 0.06, 3 trials, 1128 women).
The primary outcome measure for the babies was neonatal mortality but data were only available from two trials, in which four of the 381 babies died. There was no significant difference between the early and late cord clamping groups (RR: 0.37, 95% CI: 0.04 to 3.41). Other infant outcomes with no significant differences between early and late cord clamping were Apgar scores below 7 at 5 minutes (RR: 1.23, 95% CI: 0.73 to 2.07, 2 trials, 1342 neonates), and admission to a special care baby nursery or neonatal intensive care unit (RR: 0.79, 95% CI: 0.48 to 1.31, 4 trials, 1675 infants). Fewer infants in the early cord clamping group required phototherapy for jaundice than in the late cord clamping group (RR: 0.62, 95% CI: 0.41 to 0.96, 7 trials, 2324 infants), haemoglobin concentration was significantly lower in the early cord clamping group at 24 to 48 hours (MD: -1.49 g/dl, 95% CI: -1.78 to -1.21, 4 trials, 884 infants) and infants in the early cord clamping were more than twice as likely to be iron deficient at three to six months (RR: 2.65, 95% CI: 1.04 to 6.73, 5 trials, 1152 infants. On the negative side for late cord clamping, babies in the early clamping group were less likely to require phototherapy for jaundice (RR: 0.62, 95% CI: 0.41 to 0.96, 7 trials, 2324 infants). Unlike many of the outcomes of interest to the reviewers, birthweight was reported across a large proportion of the studies. The mean weight of babies was found to be significantly higher in the late cord clamping group (MD: 101 g increase, 95% CI 45 to 157, 12 trials, 3139 infants) but with high statistical heterogeneity (I2: 62%).
The authors write that a more liberal approach to delaying clamping of the umbilical cord in healthy term infants appears to be warranted, particularly in light of the growing evidence that delayed cord clamping increases early haemoglobin concentrations and iron stores in infants. They conclude that delayed cord clamping is likely to be beneficial, as long as access to treatment for jaundice requiring phototherapy is available.
Soure: Cochrane Library
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