title: The frequency of meconium-stained amniotic fluid increases as a function of the duration of labor.
abstract: OBJECTIVE
  The purpose of this study was to determine whether there is a relationship between the frequency of meconium-stained amniotic fluid (MSAF) and the duration of labor in term singleton gestation.
  
  
  METHODS
  The clinical characteristics of women who delivered term singleton live newborns between 2001 and 2006 were examined. The cases involving neonates with major congenital anomalies were excluded.
  
  
  RESULTS
  (1) The frequency of MSAF in term pregnancies was 18.4% (806/4376); (2) MSAF was found in only 2.8% (28/1008) of women who delivered by elective cesarean, but in 23.1% (778/3368) of women who delivered after the onset of labor (p < 0.001); (3) The longer the duration of labor (first stage, second stage, or total), the higher the frequency of MSAF (p < 0.001 for each); this remained significant after adjusting for other confounding variables such as parity, duration of rupture of membranes, gestational age at delivery, and mode of delivery (p < 0.001 for each).
  
  
  CONCLUSIONS
  MSAF was found in only 2.8% (28/1008) of women who delivered before the onset of labor, but in 23.1% (778/3368) of women who delivered after the onset of labor. The longer the duration of labor, the higher the risk of MSAF in term singleton gestation.
authors.affiliation: Department of Obstetrics and Gynecology, Seoul National University College of Medicine, Seoul, Korea.
authors.forename: Kyung A
authors.initials: KA
authors.lastname: Lee
authors.forename: Seung
authors.initials: S
authors.lastname: Mi Lee
authors.forename: Hye
authors.initials: H
authors.lastname: Jin Yang
authors.forename: Chan-Wook
authors.initials: CW
authors.lastname: Park
authors.forename: Shali
authors.initials: S
authors.lastname: Mazaki-Tovi
authors.forename: Bo
authors.initials: B
authors.lastname: Hyun Yoon
authors.forename: Roberto
authors.initials: R
authors.lastname: Romero
mesh_terms: D000328:Adult; D000653:Amniotic Fluid; D005260:Female; D006801:Humans; D007231:Infant, Newborn; D007743:Labor, Obstetric; D008470:Meconium; D011247:Pregnancy; D047929:Term Birth; D013997:Time Factors