Objective: We investigated the effect of a nuchal cord on fetal hypoxia by using amniotic fluid and cord blood erythropoietin as markers of chronic and acute hypoxia, respectively.

Methods: A total of 167 full-term pregnancies without maternal complications or fetal prelabor complications except fetal growth restriction of unknown cause were studied prospectively. Of these, 47 had a nuchal cord at delivery, and 62 had one or more complications during labor and delivery (nonreassuring fetal heart rate pattern, birth weight less than 2500 g, Apgar score at 1 minute less than 7, presence of meconium-stained amniotic fluid, oligohydramnios), and 26 had both muchal cord and at least one of the intrapartum complications.

Results: Erythropoietin levels (mean ± standard error of the mean) were not significantly different between the nuchal cord group (n = 47) and the no nuchal cord group (n = 120) in either amniotic fluid (19.3 ± 4.1 mU/mL versus 13.7 ± 1.1 mU/mL) or cord blood (57.9 ± 10.3 mU/mL versus 52.1 ± 4.9 mU/mL). Similarly, in the 62 fetuses with intrapartum complications, there were no significant differences in amniotic fluid (14.3 ± 2.0 mU/mL versus 18.8 ± 2.9 mU/mL) or cord blood erythropoietin (66.9 ± 16.8 mU/mL versus 72.6 ± 12.6 mU/mL) levels between those with (n = 26) or without a nuchal cord (n = 36). Among the 107 uncomplicated cases, however, amniotic fluid erythropoietin was significantly elevated in the nuchal cord group (25.5 ± 8.7 mU/mL, n = 21) compared with what in the no nuchal cord group (11.5 ± 0.9 mU/mL, n = 84) (P < .05), whereas there was no significant between-group difference in cord blood erythropoietin levels between nuchal cord and no nuchal cord groups (46.8 ± 10.0 mU/mL versus 43.3 ± 4.1 mU/mL). Tightness of the nuchal cord did not affect amniotic fluid or cord blood erythropoietin concentrations.

Conclusion: Although nuchal cord may not significantly increase the risk of acute or labor-associated fetal hypoxia, it appears to be an independent risk factor of mild, chronic, prelabor fetal hypoxia.