title: Birth weight threshold for postponing preterm birth.
abstract: OBJECTIVE
  The study was designed to determine the birth weight threshold at which obstetric efforts intended to delay delivery might potentially improve rates of neonatal morbidity and mortality among pregnancies delivered after spontaneous preterm labor or rupture of the membranes.
  
  
  METHODS
  We studied 1147 singleton infants with birth weights between 1000 and 2499 gm and whose only complication was spontaneous preterm labor or preterm rupture of the membranes. The Mantel-Haenszel chi 2 statistic was used to evaluate trends for neonatal mortality and several indexes of morbidity.
  
  
  RESULTS
  The birth weight threshold for neonatal mortality was 1600 gm (p < 0.001). For neonatal morbidity the threshold was between 1600 and 1900 gm (p < 0.008).
  
  
  CONCLUSIONS
  Aggressive obstetric attempts to prevent preterm birth for infants whose weights exceed 1900 gm offers few apparent potential benefits.
authors.affiliation: Department of Obstetrics and Gynecology, University of Texas Southwestern Medical Center, Dallas 75235-9032.
authors.forename: R T
authors.initials: RT
authors.lastname: DePalma
authors.forename: K J
authors.initials: KJ
authors.lastname: Leveno
authors.forename: M A
authors.initials: MA
authors.lastname: Kelly
authors.forename: M L
authors.initials: ML
authors.lastname: Sherman
authors.forename: T J
authors.initials: TJ
authors.lastname: Carmody
mesh_terms: D001724:Birth Weight; D001997:Bronchopulmonary Dysplasia / Q000453:epidemiology; D002543:Cerebral Hemorrhage / Q000453:epidemiology; D036861:Delivery, Obstetric; D004056:Differential Threshold; D005260:Female; D006801:Humans; D015994:Incidence; D007226:Infant Mortality; D007231:Infant, Newborn; D007902:Length of Stay; D007752:Obstetric Labor, Premature / Q000517:prevention & control*; D011247:Pregnancy; D012121:Respiration, Artificial; D013997:Time Factors