title: Umbilical artery pH may be a possible confounder for neonatal adverse outcomes in preterm infants exposed to antenatal magnesium.
abstract: OBJECTIVE
  To determine the normal range of ionized magnesium (IMg) levels in cord blood during preterm gestation and to investigate whether antenatal Mg administration affects neonatal intraventricular hemorrhage (IVH) or patent ductus arteriosus (PDA).
  
  
  METHODS
  In this retrospective case-control study, we reviewed 118 pregnant women with antenatal Mg administration and their infants after they gave birth at one tertiary care center between January 2006 and December 2010. Thirty-seven cases with IVH and/or PDA were compared to 81 controls by multiple logistic regression analysis. The normal range of IMg levels was determined by another 79 subjects without any tocolytic agents and possible confounders. Perinatal and neonatal characteristics were then compared between three groups divided by the IMg levels in cord serum.
  
  
  RESULTS
  The normal range of IMg levels in cord blood was determined to be 0.47 ± 0.07 mmol/L, regardless of gestational weeks. IMg level in cord serum could not be a risk factor for IVH or PDA. Elevation of IMg level in cord blood resulted in an increased incidence of IVH and a decreased incidence of PDA, but not significantly. IMg level in cord blood was inversely correlated with umbilical artery pH (p = 0.067).
  
  
  CONCLUSIONS
  There was no significant relationship between the IMg levels in cord serum and neonatal IVH and PDA. Umbilical artery pH may be a possible confounder.
authors.affiliation: Department of Obstetrics and Gynecology, Tokyo Women’s Medical University Hospital, Tokyo, Japan.
authors.forename: Etsuko
authors.initials: E
authors.lastname: Shimada
authors.forename: Masaki
authors.initials: M
authors.lastname: Ogawa
authors.forename: Yoshio
authors.initials: Y
authors.lastname: Matsuda
authors.forename: Minoru
authors.initials: M
authors.lastname: Mitani
authors.forename: Hideo
authors.initials: H
authors.lastname: Matsui
mesh_terms: D000328:Adult; D016022:Case-Control Studies; D002543:Cerebral Hemorrhage / Q000097:blood / Q000139:chemically induced / Q000175:diagnosis / Q000453:epidemiology; D015986:Confounding Factors, Epidemiologic; D004374:Ductus Arteriosus, Patent / Q000097:blood / Q000139:chemically induced / Q000175:diagnosis / Q000453:epidemiology; D005260:Female; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007231:Infant, Newborn; D007234:Infant, Premature / Q000097:blood*; D007235:Infant, Premature, Diseases / Q000097:blood / Q000139:chemically induced / Q000175:diagnosis* / Q000453:epidemiology*; D008274:Magnesium / Q000008:administration & dosage / Q000009:adverse effects*; D011247:Pregnancy; D011256:Pregnancy Outcome / Q000453:epidemiology*; D011297:Prenatal Exposure Delayed Effects / Q000097:blood / Q000139:chemically induced; D011379:Prognosis; D012189:Retrospective Studies; D015149:Tocolytic Agents / Q000008:administration & dosage / Q000009:adverse effects; D014469:Umbilical Arteries / Q000737:chemistry* / Q000378:metabolism
chemical_list: D015149:Tocolytic Agents; D008274:Magnesium