Policies for timing of cord clamping vary, with early cord clamping generally carried out in the first 60 seconds after birth, whereas later cord clamping usually involves clamping the umbilical cord more than one minute after the birth or when cord pulsation has ceased. The benefits and potential harms of each policy are debated.
To determine the effects of early cord clamping compared with late cord clamping after birth on maternal and neonatal outcomes
We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (13 February 2013).
Randomised controlled trials comparing early and late cord clamping.
Data collection and analysis
Two review authors independently assessed trial eligibility and quality and extracted data.
We included 15 trials involving a total of 3911 women and infant pairs. We judged the trials to have an overall moderate risk of bias.
Maternal outcomes: No studies in this review reported on maternal death or on severe maternal morbidity. There were no significant differences between early versus late cord clamping groups for the primary outcome of severe postpartum haemorrhage (risk ratio (RR) 1.04, 95% confidence interval (CI) 0.65 to 1.65; five trials with data for 2066 women with a late clamping event rate (LCER) of ˜3.5%, I2 0%) or for postpartum haemorrhage of 500 mL or more (RR 1.17 95% CI 0.94 to 1.44; five trials, 2260 women with a LCER of ˜12%, I2 0%). There were no significant differences between subgroups depending on the use of uterotonic drugs. Mean blood loss was reported in only two trials with data for 1345 women, with no significant differences seen between groups; or for maternal haemoglobin values (mean difference (MD) -0.12 g/dL; 95% CI -0.30 to 0.06, I2 0%) at 24 to 72 hours after the birth in three trials.
Neonatal outcomes: There were no significant differences between early and late clamping for the primary outcome of neonatal mortality (RR 0.37, 95% CI 0.04 to 3.41, two trials, 381 infants with a LCER of ˜1%), or for most other neonatal morbidity outcomes, such as Apgar score less than seven at five minutes or admission to the special care nursery or neonatal intensive care unit. Mean birthweight was significantly higher in the late, compared with early, cord clamping (101 g increase 95% CI 45 to 157, random-effects model, 12 trials, 3139 infants, I2 62%). 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, data from seven trials, 2324 infants with a LCER of 4.36%, I2 0%). Haemoglobin concentration in infants at 24 to 48 hours was significantly lower in the early cord clamping group (MD -1.49 g/dL, 95% CI -1.78 to -1.21; 884 infants, I2 59%). This difference in haemoglobin concentration was not seen at subsequent assessments. However, improvement in iron stores appeared to persist, with infants in the early cord clamping over twice as likely to be iron deficient at three to six months compared with infants whose cord clamping was delayed (RR 2.65 95% CI 1.04 to 6.73, five trials, 1152 infants, I2 82%). In the only trial to report longer-term neurodevelopmental outcomes so far, no overall differences between early and late clamping were seen for Ages and Stages Questionnaire scores.
A more liberal approach to delaying clamping of the umbilical cord in healthy term infants appears to be warranted, particularly in light of growing evidence that delayed cord clamping increases early haemoglobin concentrations and iron stores in infants. Delayed cord clamping is likely to be beneficial as long as access to treatment for jaundice requiring phototherapy is available.
我们检索了Cochrane妊娠和分娩组临床试验注册库（Cochrane Pregnancy and Childbirth Group's Trials Register） (2013年2月13日)。
产妇结局：本综述无文献报道孕产妇死亡或严重的孕产妇并发症。 早期和晚期脐带钳夹组在严重的产后出血结局（RR 1.04, 95% CI 0.65 ～1.65; 5个试验中2260名产妇晚期脐带钳夹率 （LCER）~3.5%, I20%），或产后出血量达到或超过500ml （RR 1.17 95% CI 0.94 ～ 1.44; 5个试验中2260名产妇LCER ~12%, I20%) 的比较无明显差异。使用促宫缩药物的亚组间比较差异无显著性。 仅2个试验1345名产妇报道平均失血量，或3个试验产妇产后24-72小时的血红蛋白量（平均差（MD）-0.12 g/dL; 95% CI -0.30 ～ 0.06, I20%）组间比较差异无显著性。
新生儿结局：早期和晚期脐带钳夹对于新生儿死亡或其它主要的新生儿并发症，例如：5分钟Apgar评分低于7分，或需要特殊护理者，或需要进入新生儿重症监护室者的差异无显著性（RR 0.37, 95% CI 0.04 ～3.41, 2个试验, 381 名新生儿 晚期脐带钳夹率 ~1%）。和早期脐带钳夹者相比，晚期脐带钳夹之新生儿平均出生体重较高（增加101克，95% CI 45 ～157，随机效应模型，12个试验，3139名新生儿，I262%）。 和晚期脐带钳夹者相比，早期脐带钳夹之新生儿因黄疸需光照疗法者数量较少（RR 0.62, 95% CI 0.41 － 0.96, 7个试验, 2324 名新生儿晚期脐带钳夹率 4.36%, I20%）。 出生24-48小时早期脐带钳夹之新生儿血红蛋白浓度低于晚期脐带钳夹组（MD -1.49g/dL, 95% CI -1.78 ～ -1.21; 884 infants, I259%）， 该血红蛋白浓度的差异在后续评估中消失。但是，和晚期脐带钳夹者相比，早期脐带钳夹可改善新生儿体内的铁储备至产后3～6个月缺铁时的2倍（RR 2.65 95% CI 1.04 ～ 6.73, 5个试验, 1152 名新生儿, I282%）。 仅有1个试验报道了新生儿的远期的神经发育结局，在早期和晚期的脐带钳夹按年龄和阶段的问卷调查评分差异无显著性。