title: Lactate concentration in umbilical cord blood is gestational age-dependent: a population-based study of 17 867 newborns.
abstract: OBJECTIVE
  To study the influence of gestational age on lactate concentration in arterial and venous umbilical cord blood at birth and to define gestational age-specific reference values for lactate in vigorous newborns.
  
  
  METHODS
  Population-based comparative.
  
  
  METHODS
  University hospitals.
  
  
  METHODS
  Vigorous newborns with validated umbilical cord blood samples.
  
  
  METHODS
  From 2000 to 2004, routine cord blood gases, lactate and obstetric data from two university hospitals were available for 17 867 newborns from gestational week 24 to 43. After validation of blood samples and inclusion only of singleton pregnancies aimed for vaginal delivery, 10 700 women remained. Among those, reference values were defined in 10 169 vigorous newborns, that is in newborns with a 5-minute Apgar score corresponding to the gestational age-specific median value minus 1 point score, or better.
  
  
  METHODS
  Cord lactate concentration relative to gestational age.
  
  
  RESULTS
  The arterial and venous lactate concentrations increased monotonously with gestational age from 34 weeks. Considerable differences were found between mean and median values, but after logarithmic transformation the log-lactate values were normally distributed. Simple linear regression analysis showed a significant association between the log-lactate values and gestational age (P < 10(-6), R(2)= 0.024). Reference curves were constructed after anti-logarithmic transformation. Both the gestational age and the time of the second stage of labour influenced, independently of each other, the lactate concentrations.
  
  
  CONCLUSIONS
  Lactate concentrations in arterial and venous umbilical cord blood are increasing significantly with advancing gestational age.
authors.affiliation: Department of Obstetrics and Gynaecology, Malmö University Hospital, Malmö, Sweden. nana.wiberg@med.lu.se
authors.forename: N
authors.initials: N
authors.lastname: Wiberg
authors.forename: K
authors.initials: K
authors.lastname: Källén
authors.forename: A
authors.initials: A
authors.lastname: Herbst
authors.forename: A
authors.initials: A
authors.lastname: Aberg
authors.forename: P
authors.initials: P
authors.lastname: Olofsson
mesh_terms: D001639:Bicarbonates / Q000097:blood; D001784:Blood Gas Analysis; D002245:Carbon Dioxide / Q000097:blood; D005312:Fetal Blood / Q000737:chemistry*; D005865:Gestational Age; D006801:Humans; D007231:Infant, Newborn / Q000097:blood*; D007773:Lactates / Q000378:metabolism*; D012016:Reference Values; D014469:Umbilical Arteries; D014471:Umbilical Veins
chemical_list: D001639:Bicarbonates; D007773:Lactates; D002245:Carbon Dioxide