The Length of the Human Umbilical Cord
Authors: C. W. Walker, B. G. Pye
Journal: BMJ (1960)

Introduction and Theory Not the least of several intriguing features of the human umbilical cord is its length. This varies considerably, but the most usual length is 20-22 in. (50-56 cm.) (Gardiner, 1922). Most textbooks (see Gibberd et al, 1956) follow Gardiner in asserting that a cord nearly 14 in. (35.5 cm.) long is necessary for normal delivery. It is to be expected that a relatively long cord would often be coiled round part of the body, usually the neck. Gibberd et al (1956, p. 172) claimed that this happened in about 30% of all deliveries. Furthermore, we are taught that the midwife should uncoil or cut such a cord in order to make delivery safe. There are two points to note. First, all experienced obstetricians must have seen a normal spontaneous delivery with a cord less than 12 in. (30 cm.) long. Secondly, many of them will agree with Thomas Denman (1816) that, if the child is alive when the head is born with the cord round the neck, mother and child may be safely delivered without uncoiling or cutting the cord owing to the descent of the fundus. In order to establish the range of cord lengths compatible with normal delivery we asked the midwives of the Cambridge Maternity Hospital, with the kind permission of the senior obstetric consultant and the matron, to measure the cord lengths of children born in the hospital from August, 1957, until January, 1958. The cords were measured with a steel rule, 2 feet (61 cm.) long when extended, within half an hour of delivery. It is the practice in this hospital to cut the cord about 3 in. (7.5 cm.) from the umbilicus, so that at least two measurements were made for each cord length. The cord lengths varied between 7 and 48 in. (17.8 and 121.9 cm.), the mean being 21.3 in. (54.1 cm.). Spontaneous delivery of normal children occurred with any length of cord. The cord was noted to be coiled round the neck in 17% of the cases. If normal gestation and parturition can occur with any cord length from 7 to 48 in. (17.8 to 121.9 cm.) why is the cord usually more than 20 in. (50.8 cm.) long? Observations on other mammals are scanty, but there is evidence that man shares with primates a relatively long cord. Starck (1957) found a chimpanzee, admittedly premature, with a cord over twice the crown rump length of the foetus. Fox (1929) gives accounts of the births of live anthropoid apes. In an orang outang the cord was 60 cm. (23.6 in.) long, and in a chimpanzee the cord was round the neck and was 49 cm. (19.3 in.) long. In most mammals the umbilical cord is reasonably well adapted to the immediate post-natal requirements of mother and child. We suggest that, while the length of the cord is, within wide limits, unimportant for gestation and parturition, there may be an advantage immediately after the birth of the child in having a long cord. We submit the theory that the human cord is long in order to allow the mother to pick up her helpless newborn child and carry it away from danger without exerting harmful traction on the placenta. Further, that a cord of more than 18 in. (46 cm.) will allow the child to be put to the breast with the placenta in utero and that the reflex stimulation of suckling may promote an easy and bloodless third stage. We therefore extracted from the case sheets of 223 mothers, consecutive deliveries over a period of about one month, facts about the mother and child, such as age, parity, height, weight, blood group of mother ; lengths of the three stages of labour ; normal or abnormal haemorrhage ; normal or abnormal labour : sex, length, and weight of child ; maturity of child : and the cord length. In this way we hoped to discover whether there was any correlation between cord length and the various facts abstracted. For instance, it might be argued that if the third stage of labour was very short there would not be the same need for a long cord: very tall women might be expected to bear children with cords longer than the average, and so on.