title: Downward percentile crossing as an indicator of an adverse prenatal environment.
abstract: BACKGROUND
  Postnatal health sequelae of low birth weight have been attributed to 'poor fetal growth' from inferred adverse prenatal environments; risks augmented by infant growth rates. Identifying prenatal growth-restricting events is essential to clarify pathways and mechanisms of fetal growth.
  
  
  OBJECTIVE
  The specific aim of this investigation was to examine whether an episode of preterm labor may compromise fetal growth.
  
  
  METHODS
  Fetal size at the end of the second trimester and birth were compared among women with uncomplicated pregnancies (n = 3167) and those who experienced an episode of preterm labor (<37 weeks) and subsequently delivered at term (> or =37 weeks, n = 147). Fetal weight estimated from ultrasound measures, and changes in weight standard scores across the third trimester investigated significant centile crossing (>0.67 standard deviation score change).
  
  
  RESULTS
  Fetuses delivered at term after an episode of preterm labor were smaller at birth relative to their peers than at the end of the second trimester, and were 47% more likely to experience clinically significant downward centile crossing (p < 0.05) than their peers (OR 1.47, 95% CI 1.04-2.07).
  
  
  CONCLUSIONS
  An episode of preterm labor may signal an adverse prenatal environment for term-delivered neonates. Epidemiologically silent events in the natural history of pregnancy are an understudied source of fetal growth compromise as inferred by small birth size among peers.
authors.affiliation: Department of Anthropology, Emory University, Atlanta, GA 30323, USA. mlampl@emory.edu
authors.forename: Michelle
authors.initials: M
authors.lastname: Lampl
authors.forename: Francesca
authors.initials: F
authors.lastname: Gotsch
authors.forename: Juan Pedro
authors.initials: JP
authors.lastname: Kusanovic
authors.forename: Jimmy
authors.initials: J
authors.lastname: Espinoza
authors.forename: Luis
authors.initials: L
authors.lastname: Gonçalves
authors.forename: Ricardo
authors.initials: R
authors.lastname: Gomez
authors.forename: Jyh Kae
authors.initials: JK
authors.lastname: Nien
authors.forename: Edward A
authors.initials: EA
authors.lastname: Frongillo
authors.forename: Roberto
authors.initials: R
authors.lastname: Romero
mesh_terms: D000328:Adult; D005260:Female; D047109:Fetal Development / Q000502:physiology*; D005865:Gestational Age; D006801:Humans; D007231:Infant, Newborn; D008297:Male; D007752:Obstetric Labor, Premature; D016017:Odds Ratio; D011247:Pregnancy; D011263:Pregnancy Trimester, Third; D011295:Prenatal Care; D012727:Sex Characteristics