title: Spontaneous labor increases nitric oxide synthesis during the early neonatal period.
abstract: BACKGROUND
  This paper aimed to assess the influence of spontaneous labor upon endogenous nitric oxide (NO) and endothelin 1 (ET-1) during transition to extrauterine life.
  
  
  METHODS
  The serum levels of NO metabolites (the sum of nitrites and nitrates (NOx)) and the plasma level of ET-1 were determined in 53 healthy full-term infants (spontaneous labor group; n=40, cesarean delivery group; n=13). In both groups, blood samples were obtained from a cord vein at birth and from a peripheral vein at 5 days of age.
  
  
  RESULTS
  The differences in serum NOx concentrations between the spontaneous labor group and the elective cesarean group were not significant at birth. By the age of 5 days, serum NOx concentrations had risen significantly in the spontaneous labor group to become significantly higher in the elective cesarean group.
  
  
  CONCLUSIONS
  It is speculated that spontaneous labor might enhance endogenous NO synthesis at 5 days of age.
authors.affiliation: Division of Pediatrics, Itabashi Ward Medical Association Hospital, Tokyo, Japan. enchannel@aol.com
authors.forename: A
authors.initials: A
authors.lastname: Endo
authors.forename: H
authors.initials: H
authors.lastname: Izumi
authors.forename: M
authors.initials: M
authors.lastname: Ayusawa
authors.forename: M
authors.initials: M
authors.lastname: Minato
authors.forename: S
authors.initials: S
authors.lastname: Takahashi
authors.forename: K
authors.initials: K
authors.lastname: Harada
mesh_terms: D000222:Adaptation, Physiological; D001775:Blood Circulation / Q000502:physiology; D002585:Cesarean Section; D019332:Endothelin-1 / Q000096:biosynthesis* / Q000097:blood; D005260:Female; D006801:Humans; D007231:Infant, Newborn / Q000097:blood*; D007743:Labor, Obstetric / Q000502:physiology*; D009569:Nitric Oxide / Q000096:biosynthesis* / Q000097:blood; D011247:Pregnancy
chemical_list: D019332:Endothelin-1; D009569:Nitric Oxide