Urinary oxidative stress biomarkers and accelerated time to spontaneous delivery

Background: Oxidative stress has been implicated in numerous birth outcomes, including spontaneous preterm birth. However, the relationship with presentation at delivery has been less well studied. We assessed the relationship between oxidative stress biomarkers and gestational duration with a focus on spontaneous presentation for delivery. Methods: Our sample included 740 women from a multi-center prospective cohort study, recruited from 2010 to 2012. Resultant measures of oxidative stress in pregnancy prostaglandin F_2α (PGF_2α), 8-iso-prostaglandin F_2α (8-iso-PGF_2α), and the primary 8-iso-PGF_2α metabolite were measured in third trimester urine samples. Information on presentation for delivery was abstracted from medical records. We examined associations with preterm birth using adjusted logistic models. Time to event (overall delivery and spontaneous delivery) was examined using adjusted accelerated failure time models. Results: The 8-iso-PGF_2α metabolite was associated with increased odds of overall preterm birth (OR: 1.44 [95% CI: 1.00, 2.06]), and the association with spontaneous preterm birth was similar in magnitude but not statistically significant (OR: 1.45 [95% CI: 0.96, 2.20]). We did not detect associations between other biomarkers and preterm birth, or between biomarkers and timing of overall or spontaneous delivery in accelerated failure time models. Conclusions: Our data suggest that increased oxidative stress, as indicated by the 8-iso-PGF_2α metabolite, may be associated with preterm birth. In contrast to previous studies, associations were similar among individuals with spontaneous versus non-spontaneous presentation for delivery.