The impact of variations in obstetric practice on maternal birth trauma

  • Ixora Kamisan AtanEmail author
  • Shek Ka Lai
  • Suzanne Langer
  • Jessica Caudwell-Hall
  • Hans Peter Dietz
Original Article


Introduction and hypothesis

Forceps delivery and length of second stage are risk factors of maternal birth trauma, i.e., levator ani muscle (LAM) avulsion and anal sphincter trauma. The cesarean section (CS) rate has recently become the key performance indicator because of its increase worldwide. Attempts to reduce CS rates seem to have led to an increase in forceps deliveries and longer second stages. This study aimed to determine the association between variations in obstetric practice (between hospitals) and maternal birth trauma.


This was a retrospective ancillary analysis involving 660 nulliparous women carrying an uncomplicated singleton term pregnancy in a prospective perinatal intervention trial at two Australian tertiary obstetric units. They had been seen antenatally and at 3–6 months postpartum for a standardized clinical assessment between 2007 and 2014. Primary outcome measures were sonographically diagnosed LAM and external anal sphincter (EAS) trauma.


The incidence of LAM avulsion (11.5% vs. 21.3%, P = 0.01) and composite trauma, i.e., LAM avulsion ± EAS injury (29.2% vs. 39.7%, P = 0.03) were higher in one of the two hospitals, where the forceps delivery rate was also higher (10.9% vs. 2.6%, P < 0.001). BMI (OR 0.9, P = 0.02), length of second stage (OR 1.01, P = 0.02) and forceps delivery (OR 5.24, P < 0.001) were significant predictors of the difference in LAM avulsion incidence between the hospitals. Maternal age (OR 1.06, P < 0.04) and forceps delivery (OR 8.66, P < 0.001) were significant predictors for composite trauma.


A higher incidence of LAM avulsion and composite trauma in one of the two hospitals was largely explained by a higher forceps delivery rate.


Maternal birth trauma Levator trauma Levator avulsion OASIS Anal sphincter trauma Forceps delivery 



The authors thank Rodrigo Guzman-Rojas, J Oliver Daly, Vivien Wong, Varisara Chatarasorn and Hala Phipps for their assistance in recruitment and/or data collection. This work was presented as an oral podium presentation at the 41st International Urogynecology Association (IUGA) Annual Meeting, Cape Town, South Africa, August 2016.


This study was unfunded.

Compliance with ethical standards

Conflicts of interest

KL Shek and HP Dietz have received unrestricted educational grants from GE Medical. All other authors have no conflict of interest to declare.

Details of ethics approval

The parent trial was approved by the Sydney West and Sydney South Area Health Service Human Research Ethics Committees (SWAHS HREC 07–022 and SSAHS HREC X09–0384) on 30 April 2007.


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Copyright information

© The International Urogynecological Association 2019

Authors and Affiliations

  1. 1.Sydney Medical School NepeanThe University of SydneySydneyAustralia
  2. 2.Department of Obstetrics & GynecologyUniversiti Kebangsaan Malaysia Medical Centre (UKMMC)Kuala LumpurMalaysia
  3. 3.Liverpool Clinical SchoolUniversity of Western SydneySydneyAustralia

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