[Epidemiology and clinical value of true umbilical cord knots]

To evaluate the epidemiology of true knots of the umbilical cord and their impact on pregnancy outcome.

22531 singleton deliveries were included in this retrospective study (1976-1994). Newborns with malformations were excluded. The database of the 2nd Department of Obstetrics and Gynaecology, Vienna University Hospital was analyzed.

The incidence of true knots was 1.27% (n = 286). Multiparous women are more likely to give birth to a child with a true knot of the umbilical cord than primiparae (1.52% vs. 1.01%, P < 0.001). Male fetuses are more frequently affected than females (1.49% vs. 1.04%, P = 0.01). Duration of pregnancy, fetal weight, presentation and mode of delivery are not significantly influenced by umbilical knots. Fetal acidosis (pH < 7.10) was more common in the cohort with true knots as compared with the controls (8.33% vs. 4.03%, P < 0.01). Apgar score and transfer rate to a neonatal unit were not influenced. Still-births were more common in the cohort with umbilical knots (1.7% vs. 0.6%, P < 0.05); there was no neonatal death in the cohort with true knots, however.

A fetus with a true knot of the umbilical cord is at risk for fetal death. During labour umbilical knots have no adverse effect on pregnancy outcome.