title: Neonatal respiratory morbidity and mode of delivery at term: influence of timing of elective caesarean section.
abstract: OBJECTIVE
  To establish whether the timing of delivery between 37 and 42 weeks gestation influences neonatal respiratory outcome and thus provide information which can be used to aid planning of elective delivery at term.
  
  
  METHODS
  All cases of respiratory distress syndrome or transient tachypnoea at term requiring admission to the neonatal intensive care unit were recorded prospectively for nine years.
  
  
  METHODS
  Rosie Maternity Hospital, Cambridge.
  
  
  METHODS
  During this time 33,289 deliveries occurred at or after 37 weeks of gestation.
  
  
  METHODS
  This information enabled calculation of the relative risk of respiratory morbidity for respiratory distress syndrome or transient tachypnoea in relation to mode of delivery and onset of parturition for each week of gestation at term.
  
  
  RESULTS
  The incidence of respiratory distress syndrome at term was 2.2/1000 deliveries (95% CI; 1.7-2.7). The incidence of transient tachypnoea was 5.7/1000 deliveries (95% CI; 4.9-6.5). The incidence of respiratory morbidity was significantly higher for the group delivered by caesarean section before the onset of labour (35.5/1000) compared with caesarean section during labour (12.2/1000) (odds ratio, 2.9; 95% CI 1.9-4.4; P < 0.001), and compared with vaginal delivery (5.3/1000) (odds ratio, 6.8; 95% CI 5.2-8.9; P < 0.001). The relative risk of neonatal respiratory morbidity for delivery by caesarean section before the onset of labour during the week 37+0 to 37+6 compared with the week 38+0 to 38+6 was 1.74 (95% CI 1.1-2.8; P < 0.02) and during the week 38+0 to 38+6 compared with the week 39+0 to 39+6 was 2.4 (95% CI 1.2-4.8; P < 0.02).
  
  
  CONCLUSIONS
  A significant reduction in neonatal respiratory morbidity would be obtained if elective caesarean section was performed in the week 39+0 to 39+6 of pregnancy.
authors.affiliation: Department of Obstetrics and Gynaecology, University College London Medical School, UK.
authors.forename: J J
authors.initials: JJ
authors.lastname: Morrison
authors.forename: J M
authors.initials: JM
authors.lastname: Rennie
authors.forename: P J
authors.initials: PJ
authors.lastname: Milton
mesh_terms: D002585:Cesarean Section; D036861:Delivery, Obstetric; D017558:Elective Surgical Procedures; D004739:England / Q000453:epidemiology; D005260:Female; D005865:Gestational Age; D006801:Humans; D015994:Incidence; D007231:Infant, Newborn; D007752:Obstetric Labor, Premature / Q000150:complications; D011247:Pregnancy; D012120:Respiration Disorders / Q000453:epidemiology / Q000209:etiology*; D012127:Respiratory Distress Syndrome, Newborn / Q000453:epidemiology / Q000209:etiology; D012307:Risk Factors; D013997:Time Factors