Obstetrical factors related to nuchal cord.

BACKGROUND

To investigate the intrapartum factors related to umbilical cord nuchal loops (nuchal cord) with particular reference to shoulder dystocia.

METHODS

We studied all singleton pregnancies with a vertex presentation and a birth weight of at least 2500 g from 1 January 1978 to 31 March 1997 and the 13,717 pregnancies with nuchal cord were compared to the 44,136 without nuchal cord.

RESULTS

When compared to pregnant women without nuchal cord, a greater proportion of pregnant women with nuchal cord underwent induction of labor (adjusted OR 1.09, 95% CI 1.04-1.15) and augmentation with oxytocin (adjusted OR 1.06, 95% CI 1.01-1.11). They had a longer second stage of labor (p=0.0013) and a greater proportion of primiparous women with tight nuchal cord had second stage of labor that lasted longer than two hours (adjusted OR 1.21, 95% CI 1.03-1.41). The proportion of abnormal fetal heart rate patterns was higher in the presence of nuchal cord (adjusted OR 1.61, 95% CI 1.55-1.68). Shoulder dystocia occurred more commonly in association with nuchal cord, especially when the nuchal cord was tight (adjusted OR 1.50, 95% CI 1.30-1.72 for all nuchal cord; adjusted OR 1.82, 95% CI 1.42-2.34 for tight nuchal cord).

CONCLUSIONS

Umbilical cord nuchal loops are associated with induction of labor, slow progress of labor, and shoulder dystocia.