title: Heterogeneity of perinatal outcomes in the preterm delivery syndrome.
abstract: OBJECTIVE
  Our aim was to document the differential neonatal morbidity and intrapartum and neonatal mortality of subgroups of preterm delivery.
  
  
  METHODS
  This analysis included 38,319 singleton pregnancies, of which 3,304 (8.6%) were preterm deliveries (less than 37 completed weeks) enrolled in the World Health Organization randomized trial of a new antenatal care model. We classified them as preterm deliveries after spontaneous initiation of labor, either with or without maternal obstetric and medical complications; preterm deliveries after prelabor spontaneous rupture of amniotic membranes (PROM), either with or without obstetric and medical complications; and medically indicated preterm deliveries with maternal obstetric and medical complications. Severe neonatal morbidity and neonatal mortality were the primary outcomes.
  
  
  RESULTS
  Fifty-six percent of all preterm deliveries were spontaneous, without maternal complications. Small for gestational age was increased only among the medically indicated preterm delivery group (22.3%). Very early preterm delivery (less than 32 weeks of gestation) was highest among PROM with complications (37%). For intrapartum fetal death and neonatal death, after adjusting by gestational age and other confounding variables, we found that the obstetric and medical complications preceding preterm delivery predicted the different risk levels. Conversely, for severe neonatal morbidity the clinical presentation, ie, PROM or medically indicated, predicted the increased risk.
  
  
  CONCLUSIONS
  There are differential neonatal outcomes among preterm deliveries according to clinical presentation, pregnancy complications, gestational age at delivery, and its association with small for gestational age. This syndromic nature of the condition should be considered if preterm delivery is to be fully understood and thus reduced.
authors.affiliation: World Health Organization/World Bank Special Program of Research, Development, and Research Training in Human Reproduction, Department of Reproductive Health and Research, World Health Organization, Geneva, Switzerland. villarj@who.int
authors.forename: José
authors.initials: J
authors.lastname: Villar
authors.forename: Edgardo
authors.initials: E
authors.lastname: Abalos
authors.forename: Guillermo
authors.initials: G
authors.lastname: Carroli
authors.forename: Daniel
authors.initials: D
authors.lastname: Giordano
authors.forename: Daniel
authors.initials: D
authors.lastname: Wojdyla
authors.forename: Gilda
authors.initials: G
authors.lastname: Piaggio
authors.forename: Liana
authors.initials: L
authors.lastname: Campodonico
authors.forename: Metin
authors.initials: M
authors.lastname: Gülmezoglu
authors.forename: Pisake
authors.initials: P
authors.lastname: Lumbiganon
authors.forename: Per
authors.initials: P
authors.lastname: Bergsjø
authors.forename: Hassan
authors.initials: H
authors.lastname: Ba'aqeel
authors.forename: Ubaldo
authors.initials: U
authors.lastname: Farnot
authors.forename: Leiv
authors.initials: L
authors.lastname: Bakketeig
authors.forename: Yagob
authors.initials: Y
authors.lastname: Al-Mazrou
authors.forename: Michael
authors.initials: M
authors.lastname: Kramer
mesh_terms: D000293:Adolescent; D000328:Adult; D005260:Female; D005322:Premature Rupture of Fetal Membranes / Q000150:complications; D005865:Gestational Age; D006801:Humans; D007231:Infant, Newborn; D007234:Infant, Premature; D007236:Infant, Small for Gestational Age; D007752:Obstetric Labor, Premature; D011247:Pregnancy; D011256:Pregnancy Outcome; D013577:Syndrome