Abstract
Objective: Caesarean delivery rates continue to rise globally
the reasons for which are poorly understood. We aimed to characterize
attributable factors for increasing caesarean delivery rates over a
30-year period within our health network.
Design: Observational cohort study.
Setting: Two hospitals (large tertiary referral hospital and
metropolitan hospital) in Sydney, Australia, across two time periods:
1989-1999 and 2009-2016, between which the caesarean delivery rate
increased from 19% to 30%.
Participants: All women who had a caesarean delivery after 24
weeks gestation
Methods: Data were analysed using multiple imputation and
robust Poisson regression to estimate the changes in the caesarean
delivery rate attributable to maternal and clinical factors.
Main outcome measures: Caesarean delivery.
Results: Fifty-six percent of the increase in the rate of
caesarean delivery was attributed to changes in the distribution of
maternal factors including maternal age, body mass index, parity and
history of previous caesarean delivery. When changes in the obstetric
management of multiple gestation, malpresentation and preterm singleton
birth were considered, 66% of the increase in caesarean rate was
explained. When pre-labour caesarean deliveries for maternal choice,
suspected fetal compromise, previous pregnancy issues and suspected
large fetus were excluded, 78% of the increase was explained.
Conclusions: Most of the steep rise in the caesarean delivery
rate from 19% to 30% is attributable to changes in maternal
demographic and clinical factors.
Keywords: caesarean delivery, planned caesarean, emergency
caesarean, indications, attributable risk, Robson groups
Tweetable Abstract: More than half of the increase in the rate
of caesarean delivery is attributable to changes in maternal age, BMI,
parity and history of caesarean delivery.