title: Risk of complications in a second pregnancy following caesarean section in the first pregnancy: a population-based study.
abstract: OBJECTIVE
  To estimate the risks of maternal and perinatal morbidity and mortality in a second pregnancy, attributable to caesarean section in a first pregnancy.
  
  
  METHODS
  Cross-sectional analytic study of hospital births in New South Wales, based on linked population databases.
  
  
  METHODS
  136 101 women with one previous birth who gave birth to a singleton infant in NSW in 1998-2002.
  
  
  METHODS
  Crude and adjusted odds ratios (aOR) and 95% confidence intervals (95% CI) for maternal and perinatal morbidity and mortality.
  
  
  RESULTS
  19% of mothers had a caesarean section in their first pregnancy. Compared with mothers who had had primary vaginal births, mothers who had had primary caesarean section and underwent labour in the second birth were at increased risk of uterine rupture (aOR, 12.3; 95% CI, 5.0-30.1; P < 0.0001), hysterectomy (3.5; 1.5-8.4; P < 0.01), postpartum haemorrhage (PPH) following vaginal delivery (1.6; 1.4-1.7; P < 0.0001), manual removal of placenta (1.3; 1.1-1.6; P < 0.01), infection (6.2; 4.7-8.2; P < 0.0001) and intensive care unit (ICU) admission (3.1; 2.1-4.7; P < 0.0001); among mothers who did not undergo labour (ie, had an elective caesarean section), there was a lower risk of PPH (0.6; 0.5-0.7; P < 0.0001) and ICU admission (0.4; 0.3-0.5; P < 0.0001). For infants there was increased risk of preterm delivery (1.2; 1.1-1.3; P < 0.0001) and neonatal intensive care unit admission following labour (1.6; 1.4-1.9; P < 0.0001) in the birth after primary caesarean section. The occurrence of stillbirth was not modified by labour.
  
  
  CONCLUSIONS
  Caesarean section in a first pregnancy confers additional risks on the second pregnancy, primarily associated with labour. These should be considered at the time caesarean section in the first pregnancy is being considered, particularly for elective caesarean section for non-medical reasons.
authors.affiliation: New South Wales Department of Health, Locked Bag 961, North Sydney, NSW 2059, Australia. ltayl@doh.health.nsw.gov.au
authors.forename: Lee K
authors.initials: LK
authors.lastname: Taylor
authors.forename: Judy M
authors.initials: JM
authors.lastname: Simpson
authors.forename: Christine L
authors.initials: CL
authors.lastname: Roberts
authors.forename: Emily C
authors.initials: EC
authors.lastname: Olive
authors.forename: David J
authors.initials: DJ
authors.lastname: Henderson-Smart
mesh_terms: D000328:Adult; D002585:Cesarean Section / Q000009:adverse effects / Q000706:statistics & numerical data*; D003422:Critical Care / Q000706:statistics & numerical data; D003430:Cross-Sectional Studies; D017558:Elective Surgical Procedures / Q000706:statistics & numerical data; D005260:Female; D006801:Humans; D007044:Hysterectomy / Q000706:statistics & numerical data; D007226:Infant Mortality; D007231:Infant, Newborn; D015931:Intensive Care, Neonatal / Q000706:statistics & numerical data; D008428:Maternal Mortality; D018457:Placenta, Retained / Q000453:epidemiology; D011159:Population Surveillance; D006473:Postpartum Hemorrhage / Q000453:epidemiology; D011247:Pregnancy; D011248:Pregnancy Complications / Q000453:epidemiology*; D011256:Pregnancy Outcome / Q000453:epidemiology*; D047928:Premature Birth / Q000453:epidemiology; D011645:Puerperal Infection / Q000453:epidemiology; D018570:Risk Assessment; D014597:Uterine Rupture / Q000453:epidemiology