Nuchal cord entanglements and gestational age.

The purpose of this observational study was to investigate the relation between nuchal cord entanglements and gestational age. Computerized data from our hospital perinatal database were reviewed between January 1990 and December 1994. Data from all deliveries > or = 20 weeks' gestation underwent either a Cochran-Mantel test for trend or Chi-square testing where appropriate. Of the 13,895 singleton deliveries, the finding of an entanglement increased significantly from 5.8% at 20 weeks to 29.0% at 42 weeks' gestation. The frequencies increased linearly, regardless of whether the entanglement involved a single loop (p < 0.001) or multiple loops (p < 0.002). The risk of an antepartum stillbirth was not increased in the presence of a nuchal cord entanglement, even after controlling for other risk factors. These normative data should serve as a reference for prenatal ultrasound examinations and for prospective studies intended to evaluate the predictive value of reporting this finding prenatally.