Relationship between umbilical cord morphology and nuchal cord entanglement

To determine whether tightening of nuchal cord entanglement is more likely to occur where normal cord coiling is absent and there is deficient Wharton's jelly. The study was carried out in the delivery suite of a university teaching hospital, using a prospective matched controlled-pairs survey.

Midwives identified index cases with nuchal cord entanglement at the time of delivery. The next delivery of equivalent gestation (+/- 1 week) without cord entanglement was taken as the control. Only singleton pregnancies with cephalic presentation undergoing spontaneous labor were studied. Placental insertion, nuchal entanglement (tight or loose), length, presence of knots, umbilical coiling index (UCI), and the amount of Wharton's jelly were recorded.

Longer cords were more frequent amongst male infants and were predisposed towards entanglement. There were no significant differences in the amount of Wharton's jelly, or in the UCI between tight and loose nuchal cord groups. The only measurement that differed significantly was the total cord length, with shorter cords predisposed towards tightening.

Whilst nuchal cord entanglement amongst male babies is frequently associated with long and straight umbilical cords, tightening is more likely to occur if the cord is of short or normal length. Neither low UCI nor low percentage of Wharton's jelly are predisposed towards tightening of cord entanglement.