title: Effect of delivery mode on neonatal outcome among preterm infants: an observational study.
abstract: BACKGROUND
  The optimal mode of delivery as a predictor for outcomes in preterm infants is under debate. The purpose of this study was to evaluate the effect of the delivery mode on neonatal outcome among preterm infants in different birthweight categories.
  
  
  METHODS
  A retrospective analysis of singleton preterm deliveries from 23 + 0 to 33 + 6 gestational weeks was performed. Infants were categorized based on birthweight as large for gestational age (LGA), appropriate for gestational age (AGA) and small for gestational age (SGA). The Apgar score at 5 min served as the main outcome parameter. A sensitivity analysis was performed to adjust for maternal age, parity and fetal malformations as potential confounders.
  
  
  RESULTS
  Out of 1320 singleton preterm infants, 970 (73.5%) were delivered by cesarean section and 350 (26.5%) were delivered vaginally. The AGA infants between 23 + 0 and 27 + 6 weeks showed better outcomes after cesarean section (p < 0.01 from 23 + 0-24 + 6; p = 0.03 from 25 + 0-27 + 6), whereas AGA infants between 31 + 0 and 33 + 6 gestational weeks showed better outcomes after vaginal delivery (p = 0.02). Cesarean section was beneficial in extremely and very preterm SGA infants (p = 0.01 from 25 + 0-27 + 6; p = 0.02 from 28 + 0-30 + 6). The sensitivity analysis showed no confounding effect of other variables.
  
  
  CONCLUSIONS
  There is a benefit from cesarean section in AGA preterm infants until 28 weeks of gestation and in SGA preterm infants until 31 weeks of gestation. Vaginal delivery should be chosen for moderately preterm AGA infants.
authors.affiliation: Department of Obstetrics and Gynecology, Division of Obstetrics and Feto-maternal Medicine, Medical University of Vienna, Waehringer Guertel 18-20, 1090, Vienna, Austria.
authors.forename: Iris
authors.initials: I
authors.lastname: Holzer
authors.affiliation: Department of Obstetrics and Gynecology, Division of Obstetrics and Feto-maternal Medicine, Medical University of Vienna, Waehringer Guertel 18-20, 1090, Vienna, Austria.
authors.forename: Rainer
authors.initials: R
authors.lastname: Lehner
authors.affiliation: Section for Medical Statistics (IMS), Center of Medical Statistics, Informatics and Intelligent Systems, Medical University of Vienna, Vienna, Austria.
authors.forename: Robin
authors.initials: R
authors.lastname: Ristl
authors.affiliation: Department of Obstetrics and Gynecology, Division of Obstetrics and Feto-maternal Medicine, Medical University of Vienna, Waehringer Guertel 18-20, 1090, Vienna, Austria.
authors.forename: Peter W
authors.initials: PW
authors.lastname: Husslein
authors.affiliation: Department of Pediatrics and Adolescent Medicine, Division of Neonatology, Pediatric Intensive Care and Neuropediatrics, Medical University of Vienna, Vienna, Austria.
authors.forename: Angelika
authors.initials: A
authors.lastname: Berger
authors.affiliation: Department of Obstetrics and Gynecology, Division of Obstetrics and Feto-maternal Medicine, Medical University of Vienna, Waehringer Guertel 18-20, 1090, Vienna, Austria. alex.farr@meduniwien.ac.at.
authors.forename: Alex
authors.identifier: http://orcid.org/0000-0002-4628-9052
authors.initials: A
authors.lastname: Farr
mesh_terms: D000328:Adult; D001034:Apgar Score; D001317:Austria; D001724:Birth Weight; D002585:Cesarean Section; D015331:Cohort Studies; D005113:Extraction, Obstetrical; D005260:Female; D005865:Gestational Age; D006801:Humans; D052577:Infant, Extremely Low Birth Weight; D007231:Infant, Newborn; D007235:Infant, Premature, Diseases / Q000209:etiology*; D007236:Infant, Small for Gestational Age; D008297:Male; D011247:Pregnancy; D012189:Retrospective Studies
keywords: Apgar score; Birthweight; Delivery mode; Neonatal outcome; Preterm delivery