title: Maternal vitamin D status, prolonged labor, cesarean delivery and instrumental delivery in an era with a low cesarean rate.
abstract: OBJECTIVE
  To examine the association between maternal 25-hydroxyvitamin D (25(OH)D) and adverse labor and delivery outcomes.
  
  
  METHODS
  We measured serum 25(OH)D at ⩽ 26 weeks gestation in a random subsample of vertex, singleton pregnancies in women who labored (n=2798) from the 12-site Collaborative Perinatal Project (1959 to 1966). We used labor and delivery data to classify cases of adverse outcomes.
  
  
  RESULTS
  Twenty-four percent of women were vitamin D deficient (25(OH)D <30 nmol l(-1)), and 4.5, 3.3, 1.9 and 7.5% of women had prolonged stage 1 labor, prolonged stage 2 labor, primary cesarean delivery or indicated instrumental delivery, respectively. After adjustment for prepregnancy body mass index, race and study site, 25(OH)D concentrations were not associated with risk of prolonged stage 1 or 2, cesarean delivery or instrumental delivery.
  
  
  CONCLUSIONS
  Maternal vitamin D status at ⩽ 26 weeks was not associated with risk of prolonged labor or operative delivery in an era with a low cesarean rate.
authors.affiliation: 1] Department of Epidemiology, University of Pittsburgh Graduate School of Public Health, Pittsburgh, PA, USA [2] Department of Nutritional Sciences, The Pennsylvania State University, University Park, PA, USA.
authors.forename: A D
authors.initials: AD
authors.lastname: Gernand
authors.affiliation: Departments of Pediatrics and of Obstetrics and Gynecology, Ohio State University College of Medicine and The Research Institute, Nationwide Children's Hospital, Columbus, OH, USA.
authors.forename: M A
authors.initials: MA
authors.lastname: Klebanoff
authors.affiliation: Department of Obstetrics and Gynecology, School of Medicine, Division of Maternal-Fetal Medicine, University of Pittsburgh, Magee-Womens Hospital, Pittsburgh, PA, USA.
authors.forename: H N
authors.initials: HN
authors.lastname: Simhan
authors.affiliation: 1] Department of Epidemiology, University of Pittsburgh Graduate School of Public Health, Pittsburgh, PA, USA [2] Department of Obstetrics and Gynecology, School of Medicine, University of Pittsburgh, Pittsburgh, PA, USA.
authors.forename: L M
authors.initials: LM
authors.lastname: Bodnar
mesh_terms: D000328:Adult; D002585:Cesarean Section; D005113:Extraction, Obstetrical / Q000379:methods*; D005260:Female; D006801:Humans; D007744:Obstetric Labor Complications / Q000097:blood* / Q000209:etiology; D011247:Pregnancy; D014807:Vitamin D / Q000031:analogs & derivatives* / Q000097:blood; D014808:Vitamin D Deficiency / Q000150:complications
chemical_list: D014807:Vitamin D; C104450:25-hydroxyvitamin D
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