There is no reliable research to show whether lifting or lowering the baby in the time between birth and cord clamping makes a difference to the health of the baby or the mother. If the cord is not clamped immediately at birth, blood will usually continue to flow between the placenta and the baby for a few minutes. The net blood volume transferred to the baby during this time is called 'placental transfusion'. The amount of blood and how long it continues to flow may be influenced by gravity; in other words by raising or lowering the baby relative to the placenta. Placental transfusion can give the baby about a fifth of its blood volume at birth, and so this may make a difference to the health and well-being of a baby. Placental transfusion drains the blood left in the placenta, which may help the placenta separate from the womb and may reduce overall blood loss at birth for the woman. The review authors did not find any randomised trials which compare different positions for the baby between birth and cord clamping.
阅读完整摘要
The third stage of labour is from birth of the baby until delivery of the placenta. Clamping the umbilical cord is one component of active management of the third stage. Deferring cord clamping allows blood flow between the baby and the placenta to continue; net transfer to the baby is called placental transfusion. If the cord is clamped immediately placental transfusion is restricted. Gravity is one of several factors that may influence the volume and duration of placental transfusion at both vaginal and caesarean births. Hence raising or lowering the baby whilst the cord is intact may influence placental transfusion, which in turn may affect outcome for the baby and the woman.
研究目的
To compare the effects of alternative positions for the baby between birth and cord clamping on outcome for the baby, outcome for the mother and on use of health service resources.
检索策略
We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (July 2010).
纳入排除标准
Randomised trials comparing alternative positions for the baby at vaginal and caesarean birth, before clamping of the umbilical cord.
资料收集与分析
We independently assessed trial eligibility and quality. When necessary, we contacted study authors for additional information.
主要结果
Thirty-seven studies (7559 mother-infant pairs) were excluded: 33 (7296) because they did not compare alternative positions for the baby before clamping the umbilical cord and four (263) due to quasi-random allocation. No studies met the inclusion criteria. One additional trial is ongoing.
作者结论
No randomised trials have assessed the influence of gravity on placental transfusion. Large, well-designed randomised trials are needed to assess whether gravity influences placental transfusion at vaginal and caesarean births and, if so, whether this affects short-term and long-term outcome for the baby and for the mother.
