ArticlesEffect of gravity on volume of placental transfusion: a multicentre, randomised, non-inferiority trial
Introduction
The ideal timing for umbilical cord clamping is controversial.1 Delayed cord clamping allows for passage of blood from the placenta to the baby (known as placental transfusion).2, 3, 4, 5 When cord clamping is done after 60 s, newborn babies have a median birthweight 101 g higher than those born after early clamping (before 60 s),5 probably representing an average placental transfusion of 96 mL (1 mL of blood=1·05 g).6
Delayed cord clamping increases haemoglobin in the neonatal period and decreases the risk of iron deficiency in infancy,5, 6, 7, 8 a serious public health problem in low-income9, 10 and high-income countries.11, 12, 13 The procedure is included in the guidelines for delivery room management of newborn babies from several professional organisations,14, 15, 16 but compliance with the recommendation is low.17, 18, 19, 20 This low compliance could be related to some published studies suggesting that delayed cord clamping is associated with maternal complications.1 However, results of a Cochrane meta-analysis5 clearly show no increase in maternal haemorrhage, the use of uterotonics, or duration of the third stage of labour.
On the assumption that gravity affects the volume of placental transfusion, recommendations suggest that newborn babies be held at or below the level of the vagina.19, 20, 21 This procedure is cumbersome, interferes with immediate contact with the mother, and might therefore contribute to low compliance. The effect of gravity on the volume of transfusion is based on the studies by Gunther and by Yao.2, 3, 4 Although those studies were not randomised trials and were done 35 years ago, they had rigorous methods.
If gravity plays a small or negligible part in placental transfusion, then most infants born after vaginal delivery could be placed immediately on the mother's abdomen or chest before clamping the umbilical cord. Depending on the position of the mother (lying down, semi-sitting, or sitting), the newborn baby would be above the vaginal level by about 30 cm. In view of the scarce evidence of the effect of gravity,22 we aimed to assess whether, provided umbilical cord clamping was delayed for 2 min, the volume of placental transfusion in newborn babies placed on the maternal abdomen or chest would not be inferior to that of those held at the level of the introitus.
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Study design and participants
We did this multicentre, non-inferiority, randomised controlled trial at three university-affiliated hospitals in Argentina (Trinidad Palermo Private Hospital, Buenos Aires [centre one], Maternal Infant Hospital Carlos Gianantonio, San Isidro, Buenos Aires [centre two], and Institute of Maternity Our Lady of Mercy, San Miguel de Tucumán [centre three]). The institutional review board of each participating centre approved the protocol and consent form. Mothers were approached and gave written
Results
Between Aug 18, 2011, and Aug 31, 2012, 688 newborn babies fulfilled inclusion criteria, but 142 mothers refused consent. After informed consent was obtained from mothers, some newborn babies could not be studied: 83 were delivered by caesarean section or forceps, 35 had a short umbilical cord or a tight nuchal cord, 17 needed resuscitation, and 20 were excluded for other reasons. 197 newborn babies randomly assigned to the introitus group and 194 to the abdomen group were included in the
Discussion
When cord clamping is delayed for 2 min after birth, the volume of placental transfusion for newborn babies held on the mother's abdomen or chest is not inferior to that of newborn babies held at or below the level of the introitus (panel). Several randomised controlled trials5, 8, 25 have confirmed that delayed cord clamping contributes to decreased iron deficiency in newborn babies and children, which is a serious public health problem in low-income countries,9, 10 but also prevalent in
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