Attributable factors for the rising cesarean delivery rate over 3 decades: an observational cohort study

Bradley S de Vries; Rhett Morton; Alice E Burton; Praneel Kumar; Jon A Hyett; Hala Phipps; Kevin McGeechan

doi:10.1016/j.ajogmf.2021.100555

Attributable factors for the rising cesarean delivery rate over 3 decades: an observational cohort study

Am J Obstet Gynecol MFM. 2022 Mar;4(2):100555. doi: 10.1016/j.ajogmf.2021.100555. Epub 2021 Dec 29.

Authors

Bradley S de Vries¹, Rhett Morton², Alice E Burton³, Praneel Kumar³, Jon A Hyett⁴, Hala Phipps⁵, Kevin McGeechan⁶

Affiliations

¹ School of Public Health, University of Sydney, Sydney, Australia; Sydney Institute for Women, Children and their Families. Electronic address: Bradley.DeVries@health.nsw.gov.au.
² Royal Prince Alfred Hospital, Women and Babies, Sydney, Australia; Mercy Hospital for Women, Heidelberg, Victoria, Australia.
³ Royal Prince Alfred Hospital, Women and Babies, Sydney, Australia.
⁴ Sydney Institute for Women, Children and their Families; Department of Obstetrics and Gynaecology, School of Medicine, Western Sydney University.
⁵ Sydney Institute for Women, Children and their Families; University of Technology, Sydney.
⁶ School of Public Health, University of Sydney, Sydney, Australia.

PMID: 34971814
DOI: 10.1016/j.ajogmf.2021.100555

Abstract

Background: Cesarean delivery rates continue to rise globally, the reasons for which are incompletely understood.

Objective: We aimed to characterize the attributable factors for the increasing cesarean delivery rates over a 30-year period within our health network.

Study design: This was a planned observational cohort study across 2 hospitals (a large tertiary referral hospital and a metropolitan hospital) in Sydney, Australia using data from a previously published study. The following 2 time periods were compared: 1989-99 and 2009-16, between which the cesarean delivery rate increased from 19% to 30%. The participants were all women who had a cesarean delivery after 24 weeks' gestational age. The data were analyzed using multiple imputation and robust Poisson regression to calculate the differences in the adjusted and unadjusted relative risk of cesarean delivery and estimate the changes in the cesarean delivery rate attributable to maternal and clinical factors. The primary outcome was cesarean delivery.

Results: After 576 exclusions, 102,589 births were included in the analysis. Fifty-six percent of the increase in the rate of cesarean delivery was attributed to changes in the distribution of the maternal age, body mass index, and parity and to a history of previous cesarean delivery. An additional 10% of the increase was attributed to changes in the obstetrical management of the following high-risk pregnancies: multiple gestation, malpresentation (mainly breech), and preterm singleton birth. When prelabor cesarean deliveries for maternal choice, suspected fetal compromise, previous pregnancy issues, and suspected large fetus were excluded, 78% of the increase was attributed to either maternal factors or changes in the obstetrical management of these high-risk pregnancies.

Conclusion: Most of the steep rise in the cesarean delivery rate from 19% to 30% was attributed to changes in the maternal demographic and clinical factors. This observation is relevant to developing preventative strategies that account for nulliparity, age, body mass index, and management of high-risk pregnancies.

Keywords: Robson groups; attributable risk; cesarean delivery; emergency cesarean; indications; planned cesarean.

Publication types

Observational Study
Research Support, Non-U.S. Gov't

MeSH terms

Cesarean Section*
Cohort Studies
Female
Gestational Age
Hospitals, Urban*
Humans
Infant, Newborn
Pregnancy
Retrospective Studies