True umbilical cord knot and obstetric outcome

To identify risk factors for true umbilical cord knot and to evaluate its association with fetal death, premature birth, low birth weight, small-for-gestational-age (SGA) infants, low Apgar score at 1 and 5 minutes, fetal venous pH of 7.15 or lower, and need for neonatal intensive care in singleton pregnancies.

The total population of women who delivered at Kuopio University Hospital, Kuopio, Finland, between January 2000 and August 2012 was reviewed. Risk factors for umbilical cord knot and its association with adverse pregnancy outcome were evaluated separately among women with and without true cord knot via logistic regression analysis.

Overall, 340 (1.2%) of 27 537 singleton pregnancies were affected by umbilical cord knot, with increased incidence associated with advanced maternal age, multiparity, previous spontaneous abortion, polyhydramnios, and diabetes mellitus. Umbilical cord knot was associated with a 1.58-, 8.08-, 3.90-, 3.17-, 1.67-, and 2.00-fold increased risk of neonatal intensive care, fetal death, premature birth, SGA infants, and low Apgar score at 1 and 5 minutes, respectively.

True umbilical cord knot is relatively common and is associated with increased incidence of SGA infants, premature birth, need for neonatal intensive care, and fetal death.