title: Maternal age is a risk factor for caesarean section following induction of labour.
abstract: BACKGROUND
  In Australia, more than 20% of women giving birth are 35 years or older. Advanced maternal age (AMA) is a risk factor for stillbirth, and many clinicians now recommend induction of labour (IOL) at around term gestation. The aim of this study is to determine if AMA is associated with emergency caesarean section (CS) following IOL.
  
  
  METHODS
  A retrospective cohort study was undertaken using routinely collected de-identified data. Live-born, singleton, cephalic, non-anomalous pregnancies undergoing IOL between 37 + 0 and 42 + 0 weeks were included. Previous CS and privately insured admission status were excluded. Mode of delivery was compared for women ≥38 years (AMA) and women <38 years. The primary outcome was birth by CS. Bivariate and multivariate logistic regression analyses were undertaken.
  
  
  RESULTS
  A total of 7459 women were included (≥38 years n = 718, 9.6%; <38 years n = 6741, 90.4%). AMA women had similar rates of unassisted vaginal births (OR 1.15, 95% CI 0.98-1.35, P = 0.080) and CS (OR 1.08, 95% CI 0.90-1.30, P = 0.407) but fewer instrumental deliveries (OR 0.69, 95% CI 0.55-0.87, P = 0.002) compared to women <38 years. When controlled for confounders, AMA was independently associated with a two-fold increase in birth by CS following IOL (adjusted OR 2.29; 95% CI 1.64-3.20; P < 0.001). There were no differences in neonatal outcomes.
  
  
  CONCLUSIONS
  Following IOL, AMA was associated with a two-fold increased likelihood of birth by CS in both nulliparous and multiparous women. However, the majority of AMA women birthed vaginally. Clinicians may find this information useful when counselling older women who are undergoing term IOL.
authors.affiliation: Mater Research Institute, University of Queensland, Brisbane, Queensland, Australia.
authors.forename: Liam
authors.identifier: http://orcid.org/0000-0002-4296-9499
authors.initials: L
authors.lastname: Dunn
authors.affiliation: Mater Research Institute, University of Queensland, Brisbane, Queensland, Australia.|Department of Obstetrics and Gynaecology, Mater Mothers' Hospital, Brisbane, Queensland, Australia.|School of Medicine, University of Queensland, Brisbane, Queensland, Australia.
authors.forename: Sailesh
authors.identifier: http://orcid.org/0000-0003-0832-4811
authors.initials: S
authors.lastname: Kumar
authors.affiliation: Mater Research Institute, University of Queensland, Brisbane, Queensland, Australia.|Department of Obstetrics and Gynaecology, Mater Mothers' Hospital, Brisbane, Queensland, Australia.
authors.forename: Michael
authors.initials: M
authors.lastname: Beckmann
mesh_terms: D000328:Adult; D002585:Cesarean Section; D005260:Female; D006801:Humans; D007751:Labor, Induced; D008423:Maternal Age; D010298:Parity; D011247:Pregnancy; D011256:Pregnancy Outcome; D012189:Retrospective Studies; D012307:Risk Factors
keywords: caesarean section; induced; labor; maternal age