Effect of Gravity on the Volume of Placental Transfusion in Deferred Cord Clamping: A Randomized Controlled Trial

Abstract

W hen clamping is delayed for more than one minute it is known as “deferred cord clamping” (McDonald et al., 2008), the additional blood volume transferred to the baby during this time is known as placental transfusion. The volume of placental transfusion varies widely (Farrar D., et al 2011), and can be the result of several factors, in particular the spontaneous breathing efforts of the newborn baby and the forces of uterine contractions in temporal relation to the time of clamping the cord. In the first few seconds after birth, pulmonary vascular resistance drops rapidly, which causes decreased flow through the ductusarteriosus and the descending aorta to the placenta (Bhatt S., et al 2013), (Gleason CA., et al 2012). Blood return from the placenta is the result of high pressure at the level of the umbilical vein generated by uterine contractions (Gunther M 1957). Variation in the timing of the fall in pulmonary vascular resistance and the frequency and intensity of uterine contractions are biological variables that affect the volume of placental transfusion in individual newborn babies. Additionally, the size of the umbilical vessels and the relative time of when oxytocin is given in relation to the time of birth might have an effect. Findings of a previous study with a model similar to ours recorded a large increase in weight gain in the initial seconds associated with the first uterine contractions after birth contractions (Gunther M 1957). Delayed cord clamping allows for the passage of blood from the placenta to the baby and reduces the risk of iron deficiency in infancy. To hold the infant for 2 minutes at the level of the vagina (as presently recommended on the assumption that gravity affects the volume of placental transfusion), might result in low compliance and interferes with immediate contact of the infant with the mother and so breast feeding.