title: Oxygen free radical activity in the second stage of labor.
abstract: OBJECTIVE
  To assess fetal cellular injury arising from oxygen free radical activity in relation to the duration of the second stage of labor.
  
  
  METHODS
  Cord arterial pH, malondialdehyde and organic hydroperoxides levels were determined following vaginal delivery of 326 term singleton pregnancies. Of these, 35 (11%) received epidural analgesia. The length of the second stage was recorded from the time of full dilatation to delivery.
  
  
  RESULTS
  Arterial cord pH, malondialdehyde and organic hydroperoxides were significantly correlated with duration of second stage of labor (r=-0.4492; r=0.2542; r=0.2244; respectively, p<0.001). The association of lipid peroxidation products with second stage duration was independent of cord pH. This correlation was unchanged when cases of operative delivery were excluded. However, the relationship lost statistical significance amongst cases who received epidurals.
  
  
  CONCLUSIONS
  The duration of the second stage is correlated with raised reactive oxygen species-derived lipid peroxidation products. Caution should be exercised in the management of prolonged second stage of labor.
authors.affiliation: Department of Obstetrics and Gynecology, The Chinese University of Hong Kong, Hong Kong.
authors.forename: M
authors.initials: M
authors.lastname: Mongelli
authors.forename: C C
authors.initials: CC
authors.lastname: Wang
authors.forename: W
authors.initials: W
authors.lastname: Wang
authors.forename: C C
authors.initials: CC
authors.lastname: Pang
authors.forename: M S
authors.initials: MS
authors.lastname: Rogers
mesh_terms: D000293:Adolescent; D001034:Apgar Score; D001724:Birth Weight; D005260:Female; D016166:Free Radical Scavengers / Q000032:analysis; D005865:Gestational Age; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007748:Labor Stage, Second; D008423:Maternal Age; D010100:Oxygen / Q000032:analysis*; D010298:Parity; D011247:Pregnancy; D011256:Pregnancy Outcome; D014469:Umbilical Arteries / Q000737:chemistry*
chemical_list: D016166:Free Radical Scavengers; D010100:Oxygen