title: Birth by cesarean section is associated with elevated neonatal plasma levels of dimethylarginines.
abstract: BACKGROUND
  This study was undertaken to compare the effects of vaginal delivery and cesarean section on the L-arginine-nitric oxide system by measuring levels of L-arginine, an endogenous nitric oxide synthase antagonist asymmetric dimethylarginine (ADMA), and symmetric dimethylarginine (SDMA) in the cord blood and postnatally.
  
  
  METHODS
  Plasma samples were obtained from the umbilical vein and artery at birth and from peripheral venous blood on the second postnatal day in 30 full-term newborn infants: 10 born vaginally and 20 born by cesarean section.
  
  
  RESULTS
  After vaginal delivery, ADMA concentration was higher in the umbilical vein than in the umbilical artery (mean 1.06 vs 0.90 µmol/L [P = 0.027]); and ADMA level fell after birth to 0.66 µmol/L on the second postnatal day (P = 0.007 vs umbilical artery). Newborns born by cesarean section had similar ADMA levels in umbilical arterial and venous blood, 1.19 and 1.18 µmol/L, and the ADMA level fell to 0.84 µmol/L by the second postnatal day (P < 0.001). Vaginal birth induced neither significant umbilical venoarterial difference nor a postnatal fall in SDMA. After cesarean section, SDMA was essentially the same in umbilical vein, umbilical artery and postnatal peripheral vein samples. At 2 days of age, both ADMA and SDMA levels stayed higher in infants born by cesarean section than in vaginally born infants.
  
  
  CONCLUSIONS
  ADMA level falls after both vaginal and cesarean birth, whereas SDMA level does not. The higher ADMA level after cesarean birth compared with vaginal birth may contribute to decreased nitric oxide production and bioavailability in neonatal vascular beds.
authors.affiliation: Department of Obstetrics and Gynecology, Faculty of Medicine Institute of Health Promotion and Family Care, University of Pecs, Pecs, Hungary. gabriella.vida@aok.pte.hu
authors.forename: Gabriella
authors.initials: G
authors.lastname: Vida
authors.forename: Endre
authors.initials: E
authors.lastname: Sulyok
authors.forename: Tibor
authors.initials: T
authors.lastname: Ertl
authors.forename: Jens
authors.initials: J
authors.lastname: Martens-Lobenhoffer
authors.forename: Stefanie M
authors.initials: SM
authors.lastname: Bode-Böger
mesh_terms: D001120:Arginine / Q000031:analogs & derivatives* / Q000097:blood*; D002585:Cesarean Section; D036861:Delivery, Obstetric; D005260:Female; D006801:Humans; D007231:Infant, Newborn / Q000097:blood*; D008297:Male; D011247:Pregnancy
chemical_list: C024917:symmetric dimethylarginine; C018524:N,N-dimethylarginine; D001120:Arginine