We investigated whether the second stage of labor (mode and duration) is associated with differences in biomarkers of neuronal injury in cord blood.METHODS:
Using a prospective, longitudinal biobank of cord blood specimens, all women who underwent a forceps or vacuum delivery were matched to 3 controls: (1) an unlabored cesarean, (2) the shortest second stage within 3 months and (3) the longest second stage within 3 months. Cord blood samples were analyzed for two established biomarkers of acute axonal injury: total TAU and neurofilament light polypeptide (NFL).RESULTS:
Our cohort consisted of 56 women. Maternal comorbidities and labor complications were similar across groups. Median levels of NFL, but not TAU, were statistically different across the 4 groups (forceps/vacuum 19.8 vs. unlabored cesarean 11.0 vs. short second stage 15.4 vs. long second stage 21.1; p<0.01). The most marked differences were by second stage duration irrespective of mode. Those with a second stages >2 hours (N=19) had a median NFL level more than twice that of those with an unlabored cesarean (22.7 vs. 11.0; p<0.01).CONCLUSION:
Neurofilament light polypeptide levels (NFL) are significantly greater in cord blood after a prolonged second stage. While there is no current data to suggest this is associated with long term neurologic morbidity, the robust association of NFL with neuroaxonal injury in adults may prompt further research. Using biomarkers of acute brain injury may help obstetricians further clarify safety of varying second stage durations and/or help neonatologists better predict which neonates may benefit from interventions, such as therapeutic hypothermia.