Early versus delayed cord clamping at birth: in sickness and in health
Early cord clamping, often within 10 seconds of the birth of the baby, is a common obstetric and midwifery intervention largely based now on habit. Originally thought to be important for preventing post partum haemorrhage, the intervention has persisted since it was shown to be unnecessary by the WHO.
A major reason why early cord clamping has persisted in both term and preterm births is a poor understanding of the details of fetal to neonatal transition together with the impression that the intervention is benign and may even assist transition of the baby from placental to pulmonary respiration. Early cord clamping is the intervention, not delaying the clamp until the umbilical circulation has ceased, and therefore approximating to the natural physiology. The immediate effects of early clamping on the circulation may not be obvious but when poor condition of the baby after early cord clamping occurs it is always attributed to other reasons such as intrapartum hypoxia.
Recent studies in Melbourne by Bhatt et al[i] have shown that in lambs there was a marked bradycardia after early cord clamping, which was followed by a marked hypotension with a fall in cardiac output and cerebral circulation. In humans the bradycardia can be seen in the standard normal newborn heart rate charts (Dawson et al[ii]) with the mean heart rate at one minute after birth of 80bpm ( range 20 to 140). All these babies had standard obstetric 3rd stage management of early cord clamping. By 3 minutes the cardiovascular system had recovered and the heart rate was 160bpm. Thus from the normal fetal heart rate of 110 to 160bpm the bradycardia was the result of something occurring at birth.
A study in 1964 by Brady et al[iii] attributed the bradycardia directly to early cord clamping and a very recent study published at the Birmingham conference showed no significant bradycardia after late cord clamping[iv].
Such a severe insult on the neonatal circulation cannot be acceptable, and may have adverse effects on both healthy and sick neonates. Randomised controlled studies show the significant harm of early cord clamping in the vulnerable preterm neonate. In theory early clamping will lead to hypoxia and ischaemia in the cerebral circulation and incomplete vasodilatation in the pulmonary circulation. Most babies recover and appear to tolerate the insult which results failure of randomised controlled trials to find any serious outcomes. Most babies recover which is the reason so little attention has been given to the intervention of early cord clamping.
The perceived need for resuscitation usually in the form of initiation of ventilation on a remote resuscitaire is currently preventing wider abandonment of early cord clamping. The paper shows how resuscitation with the cord intact at the side of the mother can be achieved. Arguments are put forwards to show other drivers for early cord clamping, the need for cord blood gases, the need for cord blood banking and the risk of jaundice are not logical and are put into perspective.
This opinion paper, published in Fetal and Maternal Medicine Review, is freely available for one month via the following link: http://journals.cambridge.org/fmr/clamping13
[i] Bhatt S, Alison BJ, Wallace EM, Crossley KJ, Gill AW, Kluckow M, et al. Delaying cord clamping until ventilation onset improves cardiovascular function at birth in preterm lambs. J Physiol 2013 591(Pt 8): 2113–26.
[ii] Dawson JA, Kamlin COF, Wong C, te Pas AB, Vento M, Cole TJ, et al. Changes in heart rate in the ﬁrst minutes after birth. Arch Dis Child Fetal Neonatal Ed 2010 95: F177–81
[iii] Brady J P and James LS American Journal of Obstetrics and Gynaecology, vol 84 number 1 July 1 1962, pages 1 – 12
[iv] Hutchon DJR. Cutting the Cord: an International Conference INFANT; 2013 9(5): 162. This was referenced in the original paper