Practices related to umbilical cord clamping at birth should be evidence-based. Deferred cord clamping, compared to immediate cord clamping, shows benefits for preterm neonates but this may also apply to healthy term neonates. Different blood sampling techniques are used to measure effect of deferred and immediate cord clamping. To assess the statistical and effect size differences between blood biomarkers from umbilical cord and capillary blood samples of healthy term neonates following either immediate or deferred cord clamping. Systematic review and meta-analysis. The databases PubMed, Medline, CENTRAL, CINAHL and EMBASE were systematically searched. We included studies with a randomised clinical trial design comparing deferred and immediate cord clamping among healthy term neonates born by a spontaneous vaginal birth, reporting on blood biomarkers. Studies including caesarean births and premature births/neonates were excluded. Study attributes, sampling technique, blood biomarkers, mean differences, and standard deviations were extracted. The standardised mean differences (SMD) and sampling errors were calculated for effect size estimation. Meta-analyses were performed if ≥2 studies reported the same outcome using RevMan 5. Subgroup analyses distinguished effects from umbilical cord and capillary blood samples. Moderator tests and publication bias analyses were performed using JASP. Fifteen studies were included for analysis. The biomarkers haematocrit, haemoglobin, and bilirubin were reported in ≥2 studies and thus eligible for pooling. No differences were found in haemoglobin (SMD −0.04, 95%CI −0.57 to 0.49) or bilirubin values (SMD 0.13, 95%CI −0.03 to 0.28) between umbilical cord blood samples collected after deferred or immediate cord clamping. Deferred cord clamping led to lower haematocrit values (SMD −0.3, 95%CI −0.53 to −0.07). Higher haematocrit (SMD 0.67, 95%CI 0.37 to 0.97) and haemoglobin values (SMD 0.76, 95%CI 0.56 to 0.97) from capillary blood samples, collected 2 to 72 h postpartum, showed when cord clamping was deferred. No effect was found on bilirubin values (SMD 0.13, 95%CI −0.03 to 0.28) irrespective of the sampling technique. Blood collected after deferred umbilical cord clamping showed increased haemoglobin and haematocrit values up to 72 h after birth, opposed to bilirubin values. Clinical evaluation of blood biomarkers from the umbilical cord shows different values compared to capillary blood. Sampling time and technique therefore seem essential in estimating the effects of deferred cord clamping. This meta-analysis shows that sampling time and technique are essential in estimating the effects of deferred cord clamping on neonatal blood values.

中文翻译：

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延迟脐带结扎可改善新生儿血液价值：系统评价和荟萃分析


与出生时脐带夹闭相关的做法应以证据为基础。与立即钳夹脐带相比，延迟脐带钳夹对早产儿有好处，但这也可能适用于健康足月新生儿。使用不同的血液采样技术来测量延迟和立即钳夹脐带的效果。评估立即或延迟脐带结扎后健康足月新生儿脐带和毛细血管血样本的血液生物标志物之间的统计差异和效应大小差异。系统回顾和荟萃分析。系统检索了数据库 PubMed、Medline、CENTRAL、CINAHL 和 EMBASE。我们纳入了随机临床试验设计的研究，比较了自然阴道分娩的健康足月新生儿的延迟和立即脐带结扎，并报告了血液生物标志物。包括剖腹产和早产/新生儿的研究被排除在外。提取研究属性、采样技术、血液生物标志物、平均差和标准差。计算标准化平均差（SMD）和抽样误差以估计效应大小。如果≥2项研究使用RevMan 5报告了相同的结果，则进行荟萃分析。亚组分析区分了脐带血和毛细血管血样本的影响。使用 JASP 进行主持人测试和发表偏倚分析。纳入了十五项研究进行分析。 ≥2 项研究报告了生物标志物血细胞比容、血红蛋白和胆红素，因此符合合并条件。延迟或立即脐带结扎后采集的脐带血样本之间，血红蛋白（SMD -0.04，95%CI -0.57 至 0.49）或胆红素值（SMD 0.13，95%CI -0.03 至 0.28）没有差异。 延迟脐带结扎导致血细胞比容值降低（SMD -0.3，95%CI -0.53 至 -0.07）。产后 2 至 72 小时采集的毛细血管血样的血细胞比容（SMD 0.67，95%CI 0.37 至 0.97）和血红蛋白值（SMD 0.76，95%CI 0.56 至 0.97）较高，表明推迟脐带结扎。无论采用何种采样技术，均未发现对胆红素值有影响（SMD 0.13，95%CI -0.03 至 0.28）。延迟脐带结扎后采集的血液显示，出生后 72 小时内血红蛋白和血细胞比容值有所增加，与胆红素值相反。脐带血生物标志物的临床评估显示与毛细血管血不同的值。因此，采样时间和技术对于估计延迟脐带夹紧的效果似乎至关重要。这项荟萃分析表明，采样时间和技术对于估计延迟脐带结扎对新生儿血值的影响至关重要。